Computed Tomography
Findings
Cryptorchid testis is seen as an oval soft-tissue mass along the expected course of testicular descent. Uniform enhancement is seen with intravenous (IV) radiographic contrast.
Degree of Confidence
CT is almost as accurate as US in detecting an undescended testis in the inguinal region. CT and MRI are much better than US in detecting an undescended testis that is located abdominally. In 1 study evaluating undescended testis, CT and US accuracy were 96% and 91%, respectively.
False Positives/Negatives
A lymph node can be differentiated readily by the presence of fatty hilum and its characteristic location.
Magnetic Resonance Imaging
Findings
Perform MRI from the level of the kidneys to the level of the pelvic outlet. The pulse sequences used are T1, T2, and postgadolinium T1-weighted images in the axial and coronal planes. An oval mass that appears as low signal on T1-weighted images and high signal on T2-weighted images is characteristic of an undescended testis. Identification of the mediastinum testis is helpful.
Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. 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 MRA scans. As of late December 2006, the FDA had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. 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 movingor 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.
Degree of Confidence
MRI detects the malignant degeneration in cryptorchid testis well.
False Positives/Negatives
Occasionally, bowel loops and lymph nodes can mimic the undescended testis. CT is much better at differentiating the undescended testis from the bowel loop.
Ultrasonography
Findings
The most common location of cryptorchid testis is the inguinal canal (72%), followed by prescrotal (20%) and abdominal (8%) locations. The presence of an oval mass in the inguinal canal (relatively hypoechoic in echo texture with echogenic mediastinum) is diagnostic.
Degree of Confidence
US is the modality of choice for imaging a cryptorchid testis for the following reasons:
- Of cryptorchid testes, 72% are in the inguinal canal; therefore, they are easily accessible.
- US is readily available.
- US is easy to schedule.
False Positives/Negatives
Rarely, an undescended testis can be confused with inguinal hernia; real time peristalsis confirms the presence of bowel.
Persistence of pars infravaginalis gubernaculi has been mistaken for the testis. The presence of an echogenic band (mediastinum testis) identifies the maldescended testis.
Angiography
Findings
Testicular venography has fallen out of favor because of the availability of noninvasive tests. The following findings are diagnostic:
- Demonstrated presence of the pampiniform plexus
- Visualization of testicular parenchyma
- A blind-ending testicular vein (usually indicates absent testis)
Degree of Confidence
Angiography is accurate but invasive; thus, it is not preferred. Gadolinium infusion MR venography is an alternative noninvasive method of evaluating the undescended testis, especially the vanishing testis. It is superior to MR imaging alone.
More on Cryptorchidism |
| Overview: Cryptorchidism |
 Imaging: Cryptorchidism |
| Follow-up: Cryptorchidism |
| Multimedia: Cryptorchidism |
| References |
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References
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Nguyen HT, Coakley F, Hricak H. Cryptorchidism: strategies in detection. Eur Radiol. 1999;9(2):336-43. [Medline].
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Further Reading
Keywords
undescended testis, maldescended testis, atrophic testis, anorchia
