Cryptorchidism-MRI

Case Report: Seven yr old boy with  unilateral (left) cryptorchidism  and  undetected on USG , shows  on MRI well defined rounded homogeneous  structure at deep ring  measuring approximately 13mm possibly representing undescended testis 

Teaching points by Dr MGK Murthy, Dr Sreekanth and Mr Mahesh Technologist 

1.Testis develops around 21 weeks in abdomen and is  pulled down by gubernaculum in to scrotal sac by 30 weeks . Undescended tesits at birth (particularly in prematures) is not an uncommon and most would descend by 3 months. Clinical examination needs o be done in warm environment to relax the muscles to  avoid false labelling

2.  20% of undescended testes are usually non palpable (not in the canal) . USG examination  is 45% sensitive with about 78% specificity including identification of homogenous hypo echoic structure 

3 .MRI is possibly best imaging modality today (90% Sensitive and 100%specific) and has practically replaced CT . Coronal T1 is good for gubernacular ligament demonstration  and  DW images with high b value  show intensely  hyper intense testis 

Intra abdominal / pelvic/ retroperitoeneal / other locations  are best evaluated on MR because of inherent soft tissue contrast. Differentiation  form lymph nodes(usually multiple )  / vessels (usually varying flow signals)  /Fat (suppressed on fat suppression) / bowel loops (usually longitudinality  established in contiguous sections alone with presence of air ) is not very challenging