Microultrasound may be a suitable alternative to MRI for predicting pathological tumor volume in prostate cancer lesions, according to research published March 13 in Urologic Oncology: Seminars and Original Investigations.
A team led by Arnas Rakauskas, MD, from Lausanne University Hospital in Switzerland found that while microultrasound can predict prostate volume more accurately than MRI, the latter can identify more tumors. However, both modalities tend to slightly underestimate pathological tumor and prostate volume.
“Our study shows that both microultrasound and MRI can be useful in planning focal treatments or radical prostatectomy strategy,” the Rakauskas team wrote. “However, the underestimation of real tumor size in imaging should always be considered when planning treatment margins.”
Researchers continue to explore ways that individualized prostatectomy and focal therapy can lessen treatment-related toxicity while benefitting prostate cancer patients. Multiparametric MRI and microultrasound, the latter using high frequencies of 29 MHz, have emerged as imaging modalities that can stratify risk in these patients.
Images show the measurement of microultrasound prostate and tumor volume using ExactVuTM dedicated software. Images are available for republishing under a Creative Commons license (CC BY 4.0).
Rakauskas and colleagues evaluated the accuracy of microultrasound in predicting the pathological tumor volume of single lesions against MRI in a study that included 65 men with a total of 104 lesions. They also compared the ability of microultrasound to predict prostate volume against MRI.
Microultrasound found a larger median tumor size than T2-weighted MRI, diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) sequences. However, these were all short of the median tumor size detected by pathology.
| Comparison between modalities in predicting prostate tumor volume | |
|---|---|
| Modality | Median tumor size (in ml) |
| Pathology | 1.2 |
| Microultrasound | 1.05 |
| DWI | 0.94 |
| ADC | 0.86 |
| T2-weighted MRI | 0.73 |
On average, microultrasound underestimated pathological tumor volume by 0.15 ml (p < 0.01) while DWI underestimated tumor size by 0.26 ml (p < 0.01). MRI and microultrasound underestimated the pathological prostate volume by 6 ml (p < 0.01) and 3 ml (p = 0.47), respectively.
“The amount of underestimation tended to increase with larger tumors for both imaging modalities with the smallest deviations for microultrasound,” the team wrote.
MRI detected 27% more total tumors than microultrasound. However, if only posterior tumors were counted, microultrasound had a comparable detection rate to the MRI (74% versus 71%, respectively), the researchers reported.
The study authors further highlighted that their results suggest that knowing about imaging underestimation of actual tumor sizes could be useful when planning treatments with any modality.
“Potentially, our results and results from similar studies could be used in generating AI models for live prostate lesion estimation during treatments,” they wrote.
The full study can be accessed here.
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
