Cystitis Imaging

Cystitis is defined as inflammation of the urinary bladder from any cause. It is a relatively common condition affecting both sexes and all ages. It has no racial predisposition, but females, especially those younger than 50 years, are affected more often than males. In fact, almost every woman will have had cystitis at least once in her lifetime. The incidence of cystitis is high in women because of the short length of the urethra and because of the proximity of the urethra to the anus. This anatomy makes the female urinary bladder relatively easily accessible to intestinal pathogens. ^{[1, 2, 3, 4, 5]}

(See the image below.)

Cystitis may be symptomatic or asymptomatic. Patients with bladder cystitis may present with symptoms of urgency, frequency, dysuria, hematuria, cloudy and offensive-smelling urine, or suprapubic discomfort. These symptoms may occur singly or in combination. The symptom of urgency results from the stimulation of the afferent arc of the micturition reflex; the offensive smell results from the bacterial conversion of urea to ammonia.

Interstitial cystitis

Interstitial cystitis (bladder pain syndrome, Hunner ulcer) is a painful bladder disease characterized by chronic urinary urgency, frequency, and pain without evidence of bacterial infection. Nearly 90% of patients with interstitial cystitis are women. Somatization disorder is a psychiatric condition occurring most often in women who report a variety of symptoms, such as dysmenorrhea, a burning sensation in the sex organs, dyspareunia, irregular menstrual periods, and painful urination. ^{[1, 2, 4, 5, 6, 7, 8]}

Interstitial cystitis is best diagnosed on the basis of its clinical features. The histologic changes identified by means of bladder biopsy support the diagnosis. There are no clear diagnostic criteria for interstitial cystitis, and the incidence is unknown.

The Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network has reported on urologic chronic pelvic pain disorders—specifically, interstitial cystitis/painful bladder syndrome (IC/PBS) and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). ^[9] In a study of white-matter microstructure in women with interstitial cystitis/bladder pain syndrome evaluated by diffusion tensor imaging, white-matter abnormalities were identified that correlated with pain severity, urinary symptoms, and impaired quality of life. ^[6] In another study, females with interstitial cystitis displayed increased gray-matter volume in several regions of the brain, including the right primary somatosensory cortex, the superior parietal lobule bilaterally, and the right supplementary motor area. ^[10]

Preferred examination

In patients with suspected acute cystitis, a urine sample should be obtained and sent for microscopic analysis. It should also be cultured for bacteria, and the bacterial sensitivity should be analyzed.

Cystitis is a clinical diagnosis; in most patients, imaging is not required. The diagnosis is generally made by means of cystoscopy. However, some clinicians use ultrasonography to exclude secondary causes of cystitis, such as bladder outlet obstruction and bladder calculi. Ultrasonography is also employed to look for associated renal disease; it is also a good modality for measuring bladder capacity, which may be a major concern in cases of cystitis. ^{[11, 12]}  The imaging features of cystitis are nonspecific; on imaging alone, one form of cystitis cannot be differentiated from another. Bladder tumors may cause mucosal and bladder wall changes that are similar to the changes seen in cystitis, and vice versa. Problems may even arise in differentiating malignancy from cystitis with cystoscopy, and biopsy may be required. Bladder calcification is a nonspecific finding and has several etiologies.

(See the image below.)

Common to all forms of cystitis are bladder wall and mucosal thickening; irregularity; and mucosal ulceration of varying intensity. These changes may be focal or diffuse, and findings are depicted with a variety of imaging modalities. Plain radiography is noninvasive and is good for diagnosing renal and bladder calculi and bladder calcification, as occur in some forms of chronic cystitis (see the image below).

Contrast-enhanced studies (intravenous urography [IVU] or cystography) are good at showing structural abnormalities of the kidneys, ureters, and bladder (see the image below). IVU also allows a rough assessment of renal function. Mucosal bladder irregularity, polypoid bladder masses, bladder trabeculation, and diverticula are usually well depicted on cystograms; bladder emptying may also be assessed with postvoiding cystograms.

Nuclear medicine and angiography have no defined role in the assessment and diagnosis of cystitis. Sinuses and fistulae formation may complicate certain chronic forms of cystitis. Magnetic resonance imaging (MRI) is best for imaging these conditions. MRI is also the preferred modality in cases of postirradiation and hemorrhagic cystitis. Computed tomography (CT) scans show bladder calcification to advantage; CT scanning is the preferred modality for the diagnosis of granulomatous and emphysematous cystitis.

Acute bacterial cystitis

Acute bacterial cystitis is a clinical diagnosis; imaging is not usually required. This disease is present when more than 100,000 bacteria are present in 1 mL of fresh urine. Patients with acute cystitis may present with disease of varying degrees of severity; in women, associated hemorrhage is common.

Intravenous urography (IVU) results are typically normal. However, in severe cases, generalized bullous mucosal edema may cause the bladder wall to have a cobblestone appearance. This appearance is more pronounced on radiographs, which show a partially filled bladder, or on postvoiding images, if residual contrast material is still present.

Cystitis is common in sexually active women; it may occur 2-3 times a year and responds well to antibiotics. However, for patients with more frequent episodes of cystitis or for those with antibiotic resistance, the possibility of an underlying cause should be considered. In such cases, the entire urinary tract should be imaged to exclude conditions such as calculus disease, bladder diverticula, colovesical fistula, and perivesical abscess (see the image below).

Interstitial cystitis

Interstitial cystitis is a rare, idiopathic disease that is pathologically characterized by fibrosis of the deeper layers of the bladder wall. The disease predominantly affects middle-aged women.

Urinary tract infection (UTI) is not thought to be responsible for bladder wall fibrosis, because urine is usually sterile. In advanced disease, the ureterovesical junction becomes dysfunctional, and reflux develops. The bladder ultimately becomes thinned, and ulceration and bleeding may occur.

IVU results are usually normal unless reflux has developed, in which case nonobstructive hydroureteronephrosis may be present. Cystography demonstrates a bladder with a small volume and a smooth or irregular wall. Reflux may also be seen. The main role of radiology in interstitial cystitis is in the exclusion of other diagnoses.

Eosinophilic cystitis

Eosinophilic cystitis, also known as pseudotumoral cystitis, is an uncommon inflammatory process seen in children and adults. In children, it is a self-limiting condition that resolves spontaneously and usually requires no treatment. Therefore, its recognition is important.

Predisposing factors for eosinophilic cystitis include asthma, allergies, and eosinophilic gastroenteritis. Bladder biopsy reveals pancystitis and the presence of eosinophils, among other inflammatory cells. Radiographic findings are nonspecific and include bladder wall thickening and nodular mucosa. Ureteral obstruction and vesicoureteral reflux are seen. Some authors consider eosinophilic cystitis to be a mild, relatively self-limiting form of interstitial cystitis.

Cystitis cystica

Cystitis cystica, cystitis follicularis, and bullous cystitis are names for the same disorder. This condition usually affects the lamina propria; expected findings include large cysts that resemble cobblestones; multiple, rounded filling defects at the bladder base; or both. These may closely resemble bladder carcinomas. The condition is potentially malignant. ^[11]

Chemotherapy-related cystitis

The incidence of bladder carcinoma is significantly increased in patients who undergo treatment with cyclophosphamide. Cyclophosphamide-induced cystitis is characterized by marked bladder edema and hemorrhage. IVU or cystography shows bladder wall thickening and irregularity, with intraluminal filling defects caused by blood clots. In late stages, the bladder may become fibrotic and have a small volume. Irregular bladder wall calcification may develop, but this is rare.

Methicillin cystitis

Methicillin cystitis occurs in approximately 12% of patients who undergo treatment with this drug. Patients usually develop a hemorrhagic type of cystitis. This form of cystitis is a prime example of an allergic type of drug-induced cystitis. Similar reactions have been recorded with ticarcillin, disodium carbenicillin, and penicillin G potassium.

Emphysematous cystitis

Emphysematous cystitis is nearly always associated with diabetes mellitus (see the image below); rarely, emphysematous cystitis is seen in long-standing outlet obstruction, neurogenic bladder, or bladder diverticulum. ^[13]

Conventional radiographs demonstrate irregular, streaky lucencies in the bladder wall. Gas may also be seen in the bladder or tracking proximally into the ureters. Early in the process, gas may appear in localized clusters of gas-filled vesicles; in such cases, the gas may be difficult to distinguish from bowel gas or from gas within an abscess. On contrast-enhanced studies, these gas-filled vesicles may be obscured; in appearance, these gas-filled vesicles may resemble submucosal filling defects produced by inflammatory or neoplastic processes.

With the progression of disease, a ring of gas bubbles surrounding the bladder and separated from the bladder lumen may become obvious. On IVU, gas in the bladder may be evident as a horizontal air-contrast level on images obtained with the patient erect. Contrast-enhanced studies of the bladder may show thickened, irregular, or nodular bladder mucosa.

Viral cystitis

Viral cystitis is predominantly a childhood condition, though rare cases have been described in adults, particularly those who are immunocompromised. The radiographic appearances vary with the severity of inflammation. In mild cases, contrast-enhanced radiographic studies may be normal, whereas in severe cases, large bullae and polypoid filling defects may be seen protruding into the bladder lumen. In children, viral cystitis must not be confused with embryonal rhabdomyosarcoma.

Alkaline encrusting cystitis

Alkaline encrusting cystitis is a form of chronic cystitis in which the inflamed bladder mucosa is encrusted with a layer of calcium phosphate. ^[14] Urinary infection caused by urea-splitting bacteria leads to an increase in urinary pH, promoting the precipitation of calcium salts and struvite crystals. The calcium phosphate encrustation is usually dense enough to be depicted on plain abdominal radiographs and CT scans. Although calcification is the dominant feature, the bladder wall itself is strikingly abnormal. Thickness of the bladder wall, which is often irregular and focal, is increased. The bladder lumen may be filled with debris.

Verguts and associates described a case of alkaline encrusting cystitis with unusual, but characteristic, calcifications apparent on plain radiographs and CT scans. These completely disappeared after adequate treatment. ^[15]

Schistosomiasis

Calcification in the wall of the bladder or distal ureters may be identified on plain radiographs. However, plain radiographs are not useful until calcifications have developed in the bladder or ureters. IVU findings in the bladder and distal ureters and the kidneys remain normal until late in the disease. Mucosal irregularity, inflammatory pseudopolyps, ureteritis cystica, ureteral dilatation and stricture, and reduced bladder capacity may be found with IVU, retrograde ureterography, or cystography.

The ureters may be dilated; persistent filling in the lower segment commonly occurs. Ureteral strictures may be found, and, as the disease progresses, beading of the lower ureteral segment may be observed. Subsequent ureteral fibrosis leads to calcifications of the distal ureter; on plain radiographs, these calcifications have a characteristic linear or parallel pattern. About 80% of the strictures occur in the bladder wall near the junction with the ureters.

Ureteral dilatation is often caused by vesicoureteric reflux, stenosis of the ureter, or an edematous ureteral wall that causes deficient peristalsis. The bladder wall may be indistinct or hazy as a result of submucosal edema and pseudotubercles. An intense granulomatous reaction to the ova occurs, and fibrosis eventually develops in the tunica propria, which is the site of the calcification that is visible radiologically. The calcification does represent calcified fibrous tissue, but the cause is calcification of the ova. The calcification spreads around the bladder wall and may completely encircle the bladder, appearing as a curvilinear ring. The bladder wall becomes fibrotic, but it is still distensible and maintains a normal capacity (see the images below).

KUB (kidneys, ureters, and bladder) images often reveal the pathognomonic eggshell calcification of the bladder walls and the ureters. Changes in the motility of the ureter and ureteric strictures may cause hydronephrosis and reflux nephropathy. Patients are at increased risk for stone formation and squamous cell carcinoma of the kidney and bladder. A bladder carcinoma should be considered when follow-up imaging shows an absence of wall calcification in areas that were previously calcified.

Tuberculous cystitis

Tuberculous cystitis is characterized by a gradual increase in the thickness of the bladder wall and increasing diminution of the volume of the bladder. Bladder trabeculation may develop. The vesicoureteric orifices are affected by progressive fibrosis, with subsequent hydronephrosis and hydroureters. The latter may be visible on IVU. The vesicoureteral junction orifice may become fixed and patulous, resulting in vesicoureteral reflux.

Bladder calcification is unusual; when it occurs, it is patchy. Fistulae or sinus tract formation may complicate bladder tuberculosis, though these complications are rare. They are best demonstrated on CT and MRI scans. When bladder calcification is seen on a plain abdominal radiograph, schistosomiasis is the diagnosis until proven otherwise. Tumor calcification must also be considered.

Foreign-body cystitis

One of the most common causes of foreign-body reaction in the bladder is an indwelling catheter. Catheter cystitis usually results from mechanical irritation occurring during prolonged catheterization of the bladder. The areas of inflammation are usually discrete and are generally confined to the posterior wall or the floor of the bladder. Bacteriuria is commonly associated with indwelling bladder catheters, but it is not the cause of the cystitis.

Radiographic changes are those of nonspecific inflammation or bullous edema. Indwelling catheters are associated with squamous cell carcinoma of the bladder. The development of carcinoma is related to the duration of catheter placement.

Other foreign bodies may also cause cystitis. These foreign bodies may be related to surgical procedures, sexual misadventures, or psychiatric illness. Such bodies may become encrusted with calcium salts and eventually manifest as bladder calculus.

Metallic foreign bodies are readily identified on plain abdominal radiographs. Encrustation may unmask foreign bodies that are not radiopaque; these may appear with a lucent center on plain radiographs. A mass affect is appreciated on IVU or cystography.

Nephrogenic adenoma

Nephrogenic adenoma is a proliferative response to chronic bladder infection or irritation. The name is derived from the histologic appearance of the lesion, which is similar to that of the proximal renal tubules of the nephron. The appearance is usually that of a bladder mucosal irregularity and a large, intramural mass resembling a carcinoma. Biopsy is normally required for tissue diagnosis. The lesion is not premalignant.

Malakoplakia

Malakoplakia is a granulomatous disease associated with chronic E coli infection. The bladder is the most common site affected, but the kidney may be involved. Most cases occur in middle-aged women. By far, the majority of cases are unilateral and multifocal.

The bladder lesions of malakoplakia may produce single or multiple smooth, rounded filling defects on contrast-enhanced images of the bladder. Calcification has been reported within the lesion on plain radiographs and CT scans.

Actinomycosis

When actinomycosis affects the bladder, bladder wall thickening is often observed. Cystography may show a mass attached to the bladder wall, projecting into the lumen of the bladder. Adjacent bone is often involved, and sinus tracts may form. These changes may be visible on plain abdominal radiographs, though contrast-enhanced studies or MRI may be required to depict the sinuses.

Pelvic lipomatosis

Pelvic lipomatosis is characterized by benign overgrowth of perivesical and pericolonic retroperitoneal fat. Pelvic lipomatosis may progress to cystitis, hydroureteronephrosis, and renal failure. Therefore, imaging follow-up is mandatory after diagnosis. Most cases are associated with proliferative cystitis, particularly cystitis glandularis. Pelvic lipomatosis often causes an inverted, teardrop-shaped bladder deformity. The diagnosis is made on the basis of characteristic findings on conventional radiographs and CT scans.

Extrinsic processes causing cystitis

A variety of neoplastic and inflammatory pelvic disorders may affect the urinary bladder, causing cystitis secondarily. These processes include gynecologic cancers, endometriosis, pelvic inflammatory disorders, Crohn disease, and diverticulitis, to name a few. Fistulous communication with the bladder may develop, particularly with colonic cancers, Crohn disease, and diverticulitis. The radiologic changes depend on the underlying pathology and the severity of disease. Fistulous communications may be diagnosed on contrast-enhanced images of the urinary tract, the bowel, or both.

Cystitis associated with lupus erythematosus

Patients with systemic lupus erythematosus (SLE) may sometimes develop severe cystitis marked by urgency, frequency, and dysuria. No distinguishing radiographic or cystoscopic appearances are described.

Degree of confidence

Plain radiography is noninvasive. The radiation dose is reasonably modest and reveals calcification of the urinary tract, gas within the bladder wall in emphysematous cystitis, urinary calculus disease, and foreign bodies in the bladder well.

Contrast-enhanced studies are well suited for depicting bladder mucosal irregularity, vesicoureteral reflux, bladder outlet obstruction, and abnormalities such as bladder diverticula and urachal anomalies. IVU also gives some measure of renal function.

Radiographic appearances on contrast-enhanced studies are nonspecific. The causes of various types of cystitis cannot be distinguished without clinical correlation. Sessile bladder neoplasms may have similar appearances. Foreign bodies and bladder calculi may have radiographic appearances that are similar to each other.

In emphysematous cystitis, the localized clusters of gas-filled vesicles that appear early in the process may be difficult to distinguish from bowel gas or gas in an abscess. On IVU or cystography, the gas-filled vesicles may be indistinguishable from other submucosal filling defects that inflammatory or neoplastic processes produce. Therefore, comparison of radiographs obtained with and without contrast enhancement is always advisable.

Infection and gas formation in the lumen of the urinary bladder but not in the bladder wall is often regarded as a separate entity, called primary pneumaturia or pneumocystitis. However, the 2 conditions appear to have the same etiology; both are usually caused by Escherichia coli and Aerobacter aerogenes infections, and both often occur in patients with diabetes. Clostridial infection rarely causes gas gangrene; the condition manifests as severe sepsis. Gas is often seen in the bladder lumen, with associated enterovesical fistulas.

Inverted, teardrop-shaped bladder deformity is often caused by pelvic lipomatosis, the perivesical accumulation of extravasated blood or urine, or both.

O'Dea and Malek described a similar deformity of the bladder resulting from the presence of a foreign body (a toothpick) lodged in the bladder. ^[16] Resulting urinary tract infection and perivesical inflammation may also cause this unusual bladder deformity. The bladder contour returned to normal after the foreign body was removed and the infection treated. An obstruction of the inferior vena cava may have a similar appearance.

Acute bacterial cystitis

For patients who have frequent episodes of cystitis or are antibiotic resistant, the possibility of an underlying abnormality should be considered; in such cases, the entire urinary tract should undergo imaging. CT scanning is useful when calculus disease, bladder diverticula, colovesical fistula, or perivesical abscess is under consideration.

Eosinophilic cystitis

Ichikawa et al performed 3-dimensional (3D) CT cystography in 2 patients with eosinophilic cystitis. ^[17] The cystitis manifested itself as a submucosal, elevated lesion of the bladder that mimicked a tumor. The submucosal, tumorous lesions were clearly demonstrated on 3D CT cystography; with that modality, it was possible to evaluate the mucosae of the lesions. The scans especially showed the bridging, foldlike appearance of the submucosal tumorous lesions.

Chemotherapy-related cystitis

During the acute phase of chemotherapy-induced cystitis, CT scan findings include thickening of the bladder wall and irregularity with intraluminal filling defects, caused by blood clots. In late stages, the bladder may become fibrotic; on imaging, such fibrosis manifests itself as a small-volume bladder. Irregular calcification of the bladder wall may develop. The incidence of bladder carcinoma may be markedly increased in patients who undergo treatment with cyclophosphamide. Bladder carcinoma may be readily identified on CT scans.

Emphysematous cystitis

For patients with emphysematous cystitis, CT scan findings are usually diagnostic. Intraluminal gas, however, must be differentiated from gas entering the bladder iatrogenically or from an enteric fistula. ^{[18, 19]}

Fungal cystitis

On CT scans, the thickened bladder wall is apparent, but this finding lacks specificity. In patients with poorly controlled diabetes, a bladder fungus ball may develop. When gas is present, the bladder fungus ball may have a laminated appearance; this finding is known as the double-fungus-ball wall sign. The diameter of the fungus ball is 2-10 cm. The prostate may be infected with Candida albicans in male patients with diabetes of any age. CT scanning may identify foci of low attenuation within the prostate.

Gangrenous cystitis

Gangrenous cystitis is a rare condition that arises when the bladder epithelium is necrotic and ulcerated; a pseudomembranous cast of the bladder wall forms and may detach itself. The causes of gangrenous cystitis include virulent bladder infections, particularly in cases involving immunocompromise; arterial ischemia; trauma; pressure necrosis from prolonged labor; chronic overdistention of the bladder; and the use of intravesical corrosive agents. The necrosis may sometimes involve the bladder wall, leading to perforation.

No specific radiologic findings have been identified. The correct diagnosis requires a high index of clinical suspicion in light of the patient's history. Similarly, no symptoms or clinical findings typify gangrenous cystitis; this limitation hampers diagnosis and may worsen the prognosis.

Braganca and associates described a case of a diabetic man who was hospitalized with poor general condition, dehydration, and diffuse abdominal pain in whom the diagnosis of gangrenous cystitis was made on the basis of pelvic CT scan findings. Medical treatment must be intensive, and it should begin as soon as possible. Outcomes may be favorable, as in the case reported by Braganca et al. ^[20]

Foreign-body cystitis

Foreign bodies in the urinary bladder may be readily identified on nonenhanced CT scans, though some radiolucent foreign bodies that are without encrustation may be missed. With enhancement, a mass lesion in the bladder is seen.

HIV cystitis

Human immunodeficiency virus (HIV) cystitis affects 22% of patients with HIV infection. The organisms involved include gram-negative bacteria, Candida species, beta-hemolytic streptococci, Salmonella organisms, and cytomegalovirus. Adenovirus is also a potential cause of hemorrhagic cystitis in patients with AIDS whose immunosuppression is aggravated by cytotoxic drugs. The appearance is that of nonspecific thickening.

Alkaline encrusting cystitis

See the subsection on alkaline encrusting cystitis in the Radiography section, above.

Pyocystis

Pyocystis (empyema of the urinary bladder) may develop in as many as 15% of patients with urinary diversion in whom the bladder is left in situ. If the bladder is innervated and incapable of emptying, the infection essentially becomes a closed-space infection. The diagnosis is usually made with bladder cauterization. Imaging is usually not necessary, but sonograms or CT scans may reveal debris, pus, or both in the bladder. The diagnosis should be considered in cases involving a defunctionalized bladder.

Schistosomiasis

CT scanning is the best modality for delineating the extent of the calcifications associated with schistosomiasis. In cases of schistosomiasis, bladder calcifications are characteristically linear, coarse, or floccular. The calcifications are usually first seen in the base of the bladder on plain radiographs; they most commonly appear in the anterior wall of the bladder on CT scans. The thickness of the ureteral wall is better evaluated with CT scanning than with any other modality.

Tuberculous cystitis

See the subsection on tuberculous cystitis in the Radiography section, above.

Actinomycosis

Dhamborvorn and associates described a 49-year-old woman with 2-year history of urinary frequency. ^[21] The patient had a mass at the anterior bladder wall and at the anterior abdominal wall. Cystoscopy showed an impression in the anterior bladder wall and revealed hyperemic edematous bladder mucosa. Preoperative CT scan findings suggested a tumor on the bladder. Laparotomy revealed a firm, inflammatory mass at the anterior bladder wall and another mass at the anterior abdominal wall. Partial cystectomy and excision of the mass at the anterior abdominal wall were performed. After pathologic examination confirmed actinomycosis, the patient was postoperatively treated with penicillin. She recovered well.

Lee et al describe a case of primary vesical actinomycosis, a rare disease. ^[22] Most often, vesical actinomycosis is misdiagnosed as vesical or urachal tumor; the diagnosis is usually confirmed with postoperative pathology. In the patient reported by Lee et al, the diagnosis was confirmed on the basis of repeated preoperative transabdominal biopsy. The 49-year-old woman had experienced frequency, dysuria, and intermittent gross hematuria for 2 months. CT scanning and cystoscopy showed a broad-based, edematous, protruding mass at the dome and anterior part of the bladder. Clinical findings and imaging findings initially suggested vesical malignancy. Transurethral resection and several biopsy procedures were performed. Pathology showed fibrosis with chronic inflammation. Histopathology of needle biopsy specimens confirmed the typical sulfur granules that are highly suggestive of actinomycosis.

Heer and associates describe a 73-year-old woman with extensive abdominal actinomycosis. ^[23] Ultrasonography, CT scanning, and surgical exploration revealed an extensive inflammatory tumor of the sigmoid colon involving the urinary bladder and uterus. Histologic examination revealed typical sulfur granules that were highly suggestive of actinomycosis.

Malakoplakia

Malakoplakia is characterized by the formation of multiple yellow-gray plaques in the bladder mucosa. The etiology is unknown; the condition is seen in patients with pulmonary tuberculosis, chronic osteomyelitis, chronic malignancies, or coliform cystitis.

Histologic evaluation reveals histiocytes, lymphocytes, plasma cells, and Michaelis-Gutmann bodies, which are thought to represent phagocytosed bacteria. On cystography and CT scanning, these plaques appear as rounded contour defects, primarily of the trigone.

Epstein and associates described CT scan findings in a case of malakoplakia of the bladder. ^[24] Although the CT scan findings were not considered specific for this condition, the presence of a solid bladder mass with or without extension beyond the confines of the bladder in a young woman with UTI should suggest the possibility of this diagnosis.

Pelvic lipomatosis

CT scanning is well suited for the diagnosis of pelvic lipomatosis. Nonenhanced CT images show the excessive pelvic fat to advantage, and contrast-enhanced images may show complications, such as cystitis, as well as features of obstructive uropathy.

Extrinsic processes causing cystitis

CT scanning is useful in defining the morphology of the underlying extrinsic abnormality, the extent of disease, and the causative neoplasia and staging.

Cystitis associated with lupus erythematosus

Min and associates reviewed 413 patients with SLE to investigate the etiologies of urinary bladder involvement and found that abdominal CT scanning may be a useful radiologic tool for investigating gastrointestinal tract involvement in patients with lupus cystitis. In all patients with lupus cystitis, paralytic ileus was demonstrated on plain abdominal radiography; ascites, bilateral hydroureteronephrosis, and thickened bladder wall were identified on abdominal sonography or CT scanning. Abdominal CT scanning revealed bowel wall thickening in 4 of 5 patients. The main sites of thickened bowel on abdominal CT scanning were the regions supplied by the superior mesenteric artery. ^[25]

Degree of confidence

CT scans demonstrate the calcifications of cystitis better than do plain radiographs, IVU images, or sonograms. ^[26] CT scanning is also helpful in the staging of bladder carcinomas and in depicting emphysematous cystitis.

The prostate may be infected with Candida albicans in male patients with diabetes of any age. CT scanning may depict foci of low attenuation in the prostate, but such a finding is nonspecific. The differential diagnosis includes cystitis cystica and, occasionally, a tumor.

Irwin and associates reported the incidence of calcification in bladder lesions, as evidenced on plain films, to be 0.5-7.0%. ^[27] Four cases of calcification were noted on 38 consecutive bladder CT scans (11%). Calcifications were noted on the surface and in the lesions. Calcification was present in 1 case involving malakoplakia. This may be the first report of this finding.

It is to be expected that with increasing use of CT scanning, the incidence of findings of calcification in bladder lesions will rise; such calcification should be sought. Other causes of bladder wall calcification include tuberculous schistosomiasis, bladder tumors, and postirradiation cystitis.

Recurrent cervical cancers of the pelvic stump have the potential of being misdiagnosed as interstitial cystitis and should be remembered as a false-positive sign of nonulcerative interstitial cystitis on cystoscopy, CT, and MRI. The patient’s history is a key to accurate diagnosis. ^[28]

A case of eosinophilic cystitis mimicking a bladder tumor has been reported. The 16-year old boy presented with intermittent gross hematuria and eosinophilia. CT and cystoscopy showed a sessile mass within the urinary bladder at the right vesicoureteric junction associated with bullous edema. Biopsy revealed eosinophilic cystitis. The patient responded to treatment with steroids, antimicrobials, and antihistamines. ^[29]

In vitro studies showed that the normal bladder wall appears as a band of intermediate signal intensity on T1-weighted images and as bands of low (inner) and intermediate (outer) signal intensity on T2-weighted images.

Inflamed bladder walls demonstrate 2 additional inner bands of intermediate (inner) and high (innermost) signal intensity on T1-weighted images and high (inner) and low (innermost) signal intensity on T2-weighted images. The thickness of the 2 bands of differing intensity on T2-weighted images are well correlated with the muscle layers in histopathologic specimens. The different signal intensities in the muscle layer represent a compact inner and loose outer arrangement of smooth muscle bundles.

In cases of cystitis, MRI findings are nonspecific; the appearance is that of focal or diffuse thickening of the bladder wall. On T2-weighted images, 4 layers of the bladder wall are appreciated. An innermost low-signal-intensity band and an inner high-signal-intensity band represent thickened propria and lamina propria, respectively. An outer hypointense band and an outermost band of intermediate signal intensity represent the inner compact muscle layer and the outer loose muscle layer, respectively.

After the intravenous administration of gadolinium-based contrast agent, variable enhancement of the bladder wall is observed. The intensity of enhancement depends on the severity of the inflammatory process. The feasibility of using MR hydrometry to noninvasively quantify bladder volume has been demonstrated. ^[30]

Gadolinium-based contrast agents have been linked to the development of nephrogenic systemic fibrosis (NSF), or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Systemic Fibrosis. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MR angiography (MRA) scans. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape. ^{[31, 32]}

Acute bacterial cystitis

In patients with frequent episodes of cystitis or antibiotic resistance, the possibility of an underlying abnormality should be considered; the entire urinary tract should be imaged. MRI is useful for evaluating colovesical fistula and perivesical abscess.

Hemorrhagic cystitis

MRI is particularly suited for the diagnosis of hemorrhagic cystitis. MRI may demonstrate changes of hemorrhagic cystitis and may permit a determination of disease activity. The appearances of hemorrhagic cystitis are complex. Active hemorrhage (oxyhemoglobin) has only limited paramagnetic properties; at this stage, blood behaves like simple fluid, with low signal intensity on T1-weighted MRIs and high signal intensity on T2-weighted MRIs. Also at this stage, differentiation from urine may not be possible. On T1- and T2-weighted images, the characteristics of aging blood products are as follows:

• Acute blood (intracellular deoxyhemoglobin) has low signal intensity on T1- and T2-weighted MRIs

• Intracellular methemoglobin has high signal intensity on T1-weighted images and low signal intensity on T2-weighted images

• Extracellular methemoglobin has high signal intensity on T1-weighted and T2-weighted MRIs

• Intracellular hemosiderin in an old hematoma has medium signal intensity on T1-weighted images and low signal intensity on T2-weighted images

MRI findings were reported in 2 patients with hemorrhagic cystitis secondary to radiation therapy. In 1 patient, the bladder wall was hyperintense on T1-weighted, fat-suppressed, spoiled gradient-echo images and hypointense on T2-weighted, fat-suppressed, spin-echo images. These findings were consistent with intracellular methemoglobin in the setting of subacute intramural hemorrhage. In the second patient, the bladder wall had hypointense regions on T1-weighted, fat-suppressed, spin-echo MRI scans and hyperintense regions on T2-weighted, fat-suppressed, spin-echo images. Other regions were high in signal intensity on T1- and T2-weighted, fat-suppressed, spin-echo images; these findings were consistent with active bleeding and late subacute hemorrhage, respectively. The imaging findings correlated with the patients' clinical findings.

Cystitis cystica

Cystitis cystica usually affects the lamina propria; expected findings include large cysts resembling cobblestones.

Granulomatous cystitis

In cases of tuberculosis, the earliest changes involving the bladder are those of mucosal edema and ulceration surrounding the vesicoureteral junction, which may produce ureteral obstruction and hydronephrosis. Focal intravesical granulomas are depicted with high signal intensity on T2-weighted images.

Radiation cystitis

Radiation effects are typically seen in the region of the trigone of the bladder. T2-weighted images show mildly increased signal intensity in the bladder mucosa, with relative preservation of the bladder wall thickness. However, the bladder wall may be thickened to over 5 mm in a fully distended bladder. Two signal-intensity characteristics are described: (1) uniform high signal intensity in the bladder wall and (2) low signal intensity in the inner layer, with high signal intensity at the periphery. Fistulae, sinuses, or both may develop with extensive irradiation. Gadolinium enhancement may occur as long as 2.5 years after pelvic radiation therapy.

AIDS-related cystitis

A case of cystitis caused by Toxoplasma gondii infection in a patient with AIDS has been reported. Pelvic CT scanning and MRI demonstrated thickening of the bladder wall and seminal vesicles. Cystoscopic results confirmed intravesical proliferation, which had a pseudoneoplastic appearance. The diagnosis of Toxoplasma cystitis was confirmed by the discovery of Toxoplasma cysts on histologic examination of bladder biopsy specimens. Toxoplasma cystitis is a rare cause of pseudoneoplastic bullous cystitis in patients who are HIV seropositive.

Chemotherapy-related cystitis

Chemotherapy-related cystitis is particularly associated with the use of cyclophosphamide. As many as 40% of patients treated with cyclophosphamide develop acute cystitis, which is characterized by marked bladder edema and hemorrhage.

In the acute phase, radiologic findings on IVU, ultrasonography, CT scanning, or MRI include bladder wall thickening and irregularity with intraluminal filling defects, caused by blood clots. In late stages, the bladder may become fibrotic and have a small volume. Irregular bladder wall calcification may develop. The incidence of bladder carcinoma is significantly increased in patients treated with cyclophosphamide.

Schistosomiasis

Schistosomiasis may affect the prostate and urethra; in rare cases, it causes destructive urethral fistula formation similar to tuberculosis. The fistulas may drain into the perineum, scrotum, suprapubic skin, or buttocks. MRI provides the best images of fistulous communications.

Actinomycosis

Koshiyama and associates described a patient who presented with a pelvic tumor that mimicked an advanced ovarian carcinoma; the tumor had invaded the urinary bladder, rectum, and uterus and was detected with MRI. ^[33] Following surgery, however, pathologic examination was used to diagnose actinomycosis of the left ovary. The patient's ovarian actinomycosis was complicated by diabetes mellitus.

Malakoplakia

Nukui and associates described a 63-year-old woman who presented with urinary symptoms and bilateral hydronephrosis. ^[34] Ultrasonography, CT scanning, and MRI revealed bilateral hydronephrosis caused by stenosis of the vesicoureteral junction; the stenosis was caused by a nodular mass on the posterior wall of the bladder. Cystoscopy revealed a yellowish-white mass on the trigone. Histologic findings indicated a chronic granuloma with a Michaelis-Gutmann body; the tumor was diagnosed as vesical malakoplakia.

Ollier and associates described a patient with histologically proven bladder malakoplakia associated with pelvic lymphadenopathy mimicking a neoplasm. ^[35] The nodes were hyperattenuating on CT scanning and hyperintense on MRI.

Pelvic lipomatosis

Pelvic lipomatosis may progress to cystitis, hydroureteronephrosis, and renal failure. Therefore, imaging follow-up is mandatory after diagnosis. Most cases are associated with proliferative cystitis—in particular, cystitis glandularis.

The diagnosis is made on the basis of the detection of characteristic findings on conventional radiographs and CT scan images. Multiplanar MRI allows diagnostic confirmation comparable to that with CT; it delineates cephalad displacement of the bladder base, reveals elongation of the bladder neck and posterior urethra, and shows elevation of the prostate gland and signs of cystitis.

MRI scans show characteristic medial and superior displacement of the seminal vesicles, as well as fatty tissue separating the prostate gland from the rectum. The noninvasive nature and low biologic risk of MRI are desirable features, particularly when a serial evaluation of pelvic anatomic distortion is necessary.

Extrinsic processes causing cystitis

MRI is an extremely useful tool not only for defining the pathology underlying cystitis, but also for noninvasively delineating fistulous communications and sinuses.

Degree of confidence

The major role for MRI appears to be in the staging of known malignancies. With rational use of the diagnostic tools now available and with continued improvement in MRI technology, safe and accurate diagnoses may be expected in practically all patients with diseases of the urinary tract. MRI is best for imaging these diseases. MRI is also a preferred modality in cases of postirradiation and hemorrhagic cystitis.

On MRI, epithelial granulomas that occur secondary to immunotherapy for malignant bladder tumors are similar in appearance to bladder tumors; other tuberculomas may also be similar in appearance to bladder tumors.

There are many causes of inflammation of the bladder wall, including infection, radiation, drugs (eg, cyclophosphamide), and trauma (eg, indwelling catheter, surgery). The bladder appears sonographically normal in most cases but may show thickening of its wall as a result of edema. The bladder mucosa is normally less than 2 mm thick when measured at full distention and less than 5 mm thick when nondistended (see the images below). ^{[11, 12]}

On ultrasonography, residual urine is found to be significantly increased in children with cystitis, as compared to control subjects.

Acute bacterial cystitis

Ultrasonography is useful when an underlying cause of recurrent cystitis is being considered. Such causes include associated renal disease, renal and bladder calculus disease, bladder diverticula, colovesical fistula, and perivesical abscess.

HIV cystitis

On ultrasonography, HIV cystitis appears as bladder wall thickening; this finding is nonspecific. For patients with HIV, there is concern regarding the incidence of nephrolithiasis secondary to therapy with protease inhibitors. Other areas of concern include S almonella prostatitis and inlaid cystitis.

Alkaline encrusting cystitis

Ultrasonography is expected to show bladder wall thickening, endoluminal debris, and lesion calcification.

Emphysematous cystitis

On ultrasonography, air in the bladder wall appears as intramural echogenic foci with dirty shadowing. ^[13]

Radiation cystitis

Ultrasonography may show bladder wall thickening. Renal ultrasonography is complementary to IVU and may be used to distinguish hydronephrosis from bladder/ureteral scarring, renal tumors (as a cause of bleeding), and calculus disease.

Eosinophilic cystitis

Sonographic features of eosinophilic cystitis include the following:

• A broad-based intravesical mass with a smooth or irregular outline

• A mass confined to the bladder mucosa with preservation of the muscle layers

• Trigone primarily involved with variable extension

• Generalized bladder wall thickening with mucosal irregularity

• Unilateral or bilateral hydronephrosis occurring as a result of mucosal thickening or obstruction at the vesicoureteral junction

Interstitial cystitis

In interstitial cystitis, the bladder is of small capacity, often 30-50 mL. No associated conditions are described. The disease is extremely debilitating because of the limited bladder capacity and because of pain associated with overfilling. Ultrasonography is an accurate means of calculating bladder capacity and of excluding cystitis in association with an underlying pathology, such as calculi.

Fungal cystitis

C albicans infections are opportunistic; they range from asymptomatic infections to life-threatening ones. C albicans cystitis is common as compared to other forms of cystitis. C albicans cystitis produces bladder wall thickening and a discrete, well-defined, dense fluid-fluid interface in the bladder. Debris may contain the long, threadlike pseudomycelia of the fungus. This fluid-fluid interface shifts with changes in position. The sonographic appearance is not pathognomonic. Ultrasonography has been used to monitor the progress of therapy.

Schistosomiasis

Granuloma formation within the wall may produce sonographic findings of polypoidlike thickening of the wall.

Foreign-body cystitis

Foreign bodies, either radiopaque or radiolucent, may be identified in the bladder by means of noninvasive ultrasonography.

Bladder calculi

Bladder calculi are usually secondary to chronic incomplete bladder emptying and stasis; they are often associated with cystitis. Calculi are seen as echogenic masses in the bladder lumen. These are usually mobile and cause distal shadowing. Blood clots, foreign bodies, and tumors encrusted with calcium salts have similar sonographic appearances. Ultrasonography is particularly good at depicting lucent calculi, which may not be visualized on plain abdominal radiographs.

Neurogenic bladder

Neurogenic bladder is often associated with cystitis. Therefore, the bladder should be routinely scanned before and after micturition. Loss of normal neurologic control of bladder function may affect bladder volume and appearance. Lesions of the posterior nerve roots usually give rise to a spastic bladder, which is trabeculated and which may have multiple diverticula. In long-standing cases, the bladder volume may be markedly reduced.

Malakoplakia

Malakoplakia is a granulomatous disease associated with chronic E coli infection. The bladder is the most common site affected, but the kidney may be involved. Most cases occur in middle-aged women. By far, the majority of cases are unilateral and multifocal. Ultrasonography shows an enlarged kidney associated with distortion and compression of the central echo-complex by ill-defined solid or cystic masses. When malakoplakia is unifocal, a nonspecific echogenic mass may be seen. Calcification is unusual.

Pelvic lipomatosis

Marked increase in the deposition of fat in the pelvis usually affects obese, middle-aged men. This results in bladder compression, causing the bladder to increase in craniocaudal length and to narrow from side to side. The fat is seen as echogenic material filling the pelvis around the bladder. Most other diseases that result in bladder compression give rise to hypoechoic masses.

Bladder exstrophy

In this anomaly, the bladder epithelium is exposed. This altered environment causes irritation of the mucosa; eventually, cystitis cystica develops.

Bladder exstrophy is now diagnosed on antenatal sonograms. Sonographically, bladder exstrophy may appear as an external, well-defined, solid or complex bladder mass immediately superior to the fetal genitalia. Prolonged and repeated scans fail to reveal the fetal bladder. The bladder is exposed on the abdominal wall, and diastasis of the symphysis pubis is observed. If the mucosa of the posterior bladder wall protrudes through the abdominal defect, it may cause a prominence on the abdominal wall. Free communication between the bladder and the amniotic cavity prevents bladder distention.

The renal collecting system and ureters need not be dilated; unilateral or horseshoe kidneys may be found. Uterine and adnexal anomalies are relatively frequent findings. The pubis is abnormally wide, and the umbilical cord insertion may be abnormal.

Chronic cystitis associated with bladder exstrophy

Bladder exstrophy is a congenital anomaly of the urinary bladder in which the posterior wall of the bladder lies exposed. Most cases of bladder exstrophy are now diagnosed antenatally by means of ultrasonography. The exposed bladder mucosa is subject to irritation as a result of altered environment that eventually develops into cystitis cystica and cystitis glandularis. No imaging is normally required unless there are associated changes in the upper urinary tract; in such cases, ultrasonography may be used to look for morphologic changes in the kidneys.

The limited diagnostic value of clinical evaluation and plain radiography in the detection of abscesses has led to widespread use of sophisticated imaging techniques, including gallium-67 (⁶⁷Ga) scintigraphy and indium-111 (¹¹¹In) white blood cell (WBC) count scintigraphy. However, scintigraphy has not been applied in the imaging of cystitis apart from a single study of lupus cystitis, in which ⁶⁷Ga was used. ^[36]

Dimercaptosuccinic acid (DMSA) scanning may be useful in the workup of patients who potentially have cystitis. In one study, investigators concluded that the clinical, biological, and ultrasonographic parameters did not permit the accurate differentiation of cystitis from pyelonephritis in children with UTI and that that it did not allow the identification of cases of severe renal damage. They recommended that DMSA scanning be added to the initial workup of children with UTI.

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) positivity has been described in a case of emphysematous cystitis. The 84-year-old man was undergoing FDG-PET to monitor a known diagnosis of IgG4-related nodular sclerosis. Images revealed emphysematous cystitis that subsequently developed sepsis with Escherichia coli. This case highlights another cause of a positive FDG-PET scan in a life-threatening complication of cystitis. ^[37]

Degree of confidence

Gallium-67 and ¹¹¹In WBC count scintigraphy has been widely used in the diagnosis of abdominal inflammatory and infective disorders. The role of these diagnostic tools is limited in the workup of cystitis but may prove useful for investigating inflammatory disorders affecting the bladder extrinsically.

Goodgold and Samuels reported misleading findings on ¹¹¹In leukocyte images. ^[38]  Indium-111 leukocyte imaging usually yields images that are easily interpreted. However, 5 potentially misleading cases were noted among more than 200 scans obtained over 4 years. These included scans from 2 cases of bladder visualization without bladder inflammation and 3 cases of abdominal activity without intra-abdominal abscess or inflammatory bowel disease. Migration of leukocytes from other true pathologic sites and technical factors were responsible for the activity seen.