Contrast-enhanced ultrasound evaluation of testicular interstitial cell tumours in conscious non-sedated dogs

Testicular tumours are the most common neoplasms of the genital system in male dogs. The three main types reported in dogs are interstitial cell tumour, seminoma and Sertoli cell tumour. Interstitial cell tumour is related to the presence of single or multiple nodules inside the testicular parenchyma, and it is detected by palpation or is often an incidental finding during ultrasonography examination. Contrast-enhanced ultrasound allows characterisation of the perfusion of the testicular lesion and reveals the micro-vascularisation; however, perfusion parameters may be strongly influenced by sedative drug administration, so our aim was to evaluate qualitative and quantitative perfusion of a single type of tumour (interstitial cell tumour) with contrast-enhanced ultrasound in conscious dogs to exclude any influence of pharmacological agents on vascular flow. Thirty dogs with focal testicular lesions found by palpation and/or by ultrasound (B-mode and Doppler) examination were selected; contrast-enhanced ultrasound was performed only in subjects that presented testicular focal lesions. After orchiectomy, testes were submitted to histological evaluation; 2-minute clips recorded during contrast-enhanced ultrasound were analysed only in the case of dogs with interstitial cell tumours (n = 12). Contrast medium showed wash-in at around 25-30 seconds, at the same time as the surrounding tissue: lesions were hyperenhancing, homogeneous or inhomogeneous with rim enhancement and contained prominent inner vessels; however, enhancement of small regions was absent. Quantitative analysis demonstrated significantly higher PI% (P = 0.005), regional blood volume (P = 0.02) and regional blood flow (P = 0.007) values in lesions than in surrounding tissue; no differences were found for time-to-peak and mean transit time. In conclusion, the contrast-enhanced ultrasound pattern observed in conscious non-sedated dogs with interstitial cell tumour was similar to the pattern described in a previous study in dogs after intramuscular administration of medetomidine (10 µg/kg) and butorphanol (0.2 mg/kg).