Tumor vascularization is a key indicator of biological activity, as angiogenesis plays a crucial role in tumor growth by supplying oxygen and nutrients to neoplastic cells¹. In canine testicular tumors, assessing vascular patterns can provide valuable insights beyond what structural imaging offers. 

Doppler ultrasonography has emerged as a practical tool for evaluating blood flow within testicular lesions, adding a functional dimension to diagnosis. 

Color Doppler and Vascular Patterns 

Color Doppler ultrasonography enables visualization of blood flow distribution within and around lesions. In this study, distinct vascular patterns were observed across tumor types. Leydig cell tumors predominantly exhibited perilesional or combined peri/intralesional vascularization in 81.2% of cases, whereas other tumors, such as seminomas and Sertoliomas showed mainly intralesional blood flow¹. 

However, despite these trends, vascular patterns were not exclusive. The overlap between tumor types limits the ability of color Doppler to provide definitive differentiation. Additionally, in 5 out of 33 tumors, color Doppler failed to detect any vascularization, highlighting its limited sensitivity, particularly in small vessels or lesions with low blood flow¹. 

Pulsed Doppler and Hemodynamic Parameters¹ 

Pulsed Doppler adds quantitative assessment by measuring parameters such as peak systolic velocity (PSV) and end diastolic velocity (EDV), along with derived indices like resistive index (RI) and pulsatility index (PI). These indices reflect downstream vascular resistance and waveform variability. 

In the study, Sertoliomas demonstrated significantly higher RI and PI values compared to seminomas. However, since PSV and EDV did not differ significantly across tumor types, interpreting these indices becomes complex. As they are derived from primary velocity measurements, their reliability is questionable in this context. 

Moreover, pulsed Doppler detected vascularization in only 16 out of 33 tumors, limiting its applicability in routine clinical practice. 

Power Doppler: Improved Sensitivity but Limited Specificity 

Power Doppler imaging offers greater sensitivity for detecting low-velocity blood flow and is less affected by insonation angle compared to color Doppler². In this study, it identified vascular signals in 28 out of 33 lesions, outperforming color Doppler in detection. 

Despite this advantage, power Doppler did not improve tumor differentiation. The vascular distribution patterns remained similar to those observed with color Doppler, and no significant differences were found in the number of detected vascular signals across tumor types. 

Clinical Interpretation of Doppler Findings¹ 

While Doppler techniques provide valuable information about blood flow, their role in differentiating tumor types remains limited. The observed vascular patterns and hemodynamic parameters show considerable overlap, reducing their diagnostic specificity. 

However, Doppler imaging still holds clinical value. It can identify abnormal perfusion, distinguish neoplastic from non-neoplastic tissue to some extent, and provide indirect insights into tumor angiogenesis. 

Conclusion 

Doppler ultrasonography represents an important step toward functional imaging of testicular tumors in dogs. It enhances the understanding of vascular architecture and perfusion, which are closely linked to tumor biology. However, its limitations in sensitivity and specificity prevent it from serving as a standalone diagnostic tool for tumor differentiation. A combined approach with other imaging modalities is necessary to achieve a more accurate and clinically meaningful assessment. 

Reference 

1. Orlandi R, Vallesi E, Boiti C, Polisca A, Bargellini P, Troisi A. Characterization of testicular tumor lesions in dogs by different ultrasound techniques. Animals. 2022 Jan 17;12(2):210. https://doi.org/10.3390/ani12020210 

2. Oglat AA, Matjafri MZ, Suardi N, Oqlat MA, Abdelrahman MA, Oqlat AA. A review of medical doppler ultrasonography of blood flow in general and especially in common carotid artery. Journal of medical ultrasound. 2018 Jan 1;26(1):3-13. https://journals.lww.com/jmut/_layouts/15/oaks.journals/downloadpdf.aspx?an=00042365-201826010-00002