Imaging Guidelines for Groin, Penis, and Scrotum

Introduction to Imaging Modalities

The American College of Radiology recommends high-frequency (7.5-10 MHz) ultrasound with color and power Doppler as the first-line imaging modality for evaluating the groin, penis, and scrotum due to its high diagnostic accuracy, excellent anatomic detail, and ability to assess vascular flow without radiation exposure 1
The European Urology association recommends MRI when there is uncertainty regarding corporal invasion and/or feasibility of organ-sparing surgery, as it is superior for evaluating the primary tumor extent, assessing corporal invasion, and planning surgical approaches 2

The American College of Radiology recommends ultrasound duplex Doppler as the most appropriate initial imaging modality (strong recommendation) for evaluating the scrotum, with findings requiring urgent urological consultation including absent testicular blood flow, testicular rupture, and signs of Fournier gangrene 1
Ultrasound provides nearly 100% sensitivity for detecting intrascrotal masses and 98-100% accuracy for differentiating between intratesticular and extratesticular processes 1
The optimal ultrasound examination should include grayscale imaging of both testes and epididymides, color and power Doppler evaluation of testicular and epididymal blood flow, comparison with the contralateral side, and assessment of the surgical site and spermatic cord 3, 1
Ultrasound with Doppler evaluation can identify decreased or absent flow, suggesting ischemic orchitis or infarction, and can detect epididymal enlargement and hyperemia suggestive of epididymitis 1
Ultrasound findings of absent flow suggest complete ischemia requiring urgent urological consultation and likely surgical exploration, while decreased flow may indicate partial ischemia requiring close monitoring or intervention 3, 1
Normal or increased flow on ultrasound may suggest inflammatory processes that could be managed conservatively, as recommended by the American College of Radiology 3, 1, 4

The European Urology association recommends MRI when there is uncertainty regarding corporal invasion, and the protocol should include small field-of-view T1 and T2-weighted images in multiple planes 2
The American College of Radiology recommends MRI as a secondary imaging option when ultrasound findings are equivocal or further tissue characterization is needed, with advantages including better tissue characterization, larger field of view, and less operator dependence 5
MRI is not recommended as initial imaging but may be used as a problem-solving tool if ultrasound findings are equivocal, according to the American College of Radiology 3, 4

The European Urology association recommends physical examination of both groins as essential for lymph node staging, with surgical lymph node staging recommended for high-risk patients (T1b or higher) if no palpable nodes (cN0), and image-guided biopsy recommended before treatment if palpable nodes (cN+) 2
The Journal of Urology recommends 18FDG-PET/CT or CT of chest and abdomen to exclude distant metastases for confirmed nodal metastasis, although PET/CT cannot reliably detect metastatic deposits less than 10mm and may not distinguish between inflammatory and metastatic uptake 6

The American College of Radiology recommends against using CT as the initial imaging modality due to poor soft tissue contrast, with limited value in scrotal and penile imaging 5
The Journal of Urology recommends against using CT for lymph node evaluation due to poor soft tissue contrast, although it may be useful for quantifying disease burden and assessing treatment response in patients with positive lymph nodes 6
CT is not routinely used for initial evaluation of acute scrotal pain without trauma, as recommended by the American College of Radiology 4

The American College of Radiology notes that ultrasound is operator-dependent, with experience with scrotal and penile imaging crucial, and false negatives can occur with intermittent testicular torsion on both ultrasound and MRI 1
The Journal of Urology notes that PET/CT cannot reliably detect metastatic deposits less than 10mm and may not distinguish between inflammatory and metastatic uptake 6
Nuclear medicine scan is not routinely used for initial evaluation of acute scrotal pain, according to the American College of Radiology 3