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Micro-ultrasound sensitivity 0.84 and specificity 0.41 for prostate cancer in five prospective studiesMicro-ultrasound helps find prostate cancer when MRI is not available

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Key Takeaway
Consider micro-ultrasound as a rule-out adjunct for prostate cancer, noting its high sensitivity but low specificity and modest post-test probability shifts.

This is a systematic review and diagnostic test accuracy meta-analysis of five prospective studies evaluating standalone 29-MHz micro-ultrasound as an index test for classifying clinically significant prostate cancer, using histopathology as the reference standard. The meta-analysis found a pooled sensitivity of 0.84 (95% CI 0.65-0.94) and a pooled specificity of 0.41 (95% CI 0.25-0.59). The positive likelihood ratio was 1.45 (95% CI 1.17-1.80), the negative likelihood ratio was 0.37 (95% CI 0.23-0.61), and the diagnostic odds ratio was 3.95 (95% CI 2.48-6.30). Post-test probability shifts were approximately 33% after a positive test and approximately 11% after a negative test.

The authors acknowledge substantial heterogeneity across studies, which they attribute to differences in thresholds and clinical spectrum. They note that spectrum-related factors were associated with lower specificity and that no covariate robustly altered sensitivity in exploratory analyses, given the small number of studies. The review highlights the need for standardized PRI-MUS thresholds, reader training, and larger multicenter studies.

Practice relevance supports micro-ultrasound as a complementary or triage adjunct, particularly when multiparametric MRI is unavailable, contraindicated, or delayed. The evidence is limited by heterogeneity and the small number of studies, and the findings should be interpreted cautiously.

This systematic review and diagnostic test accuracy meta-analysis looked at five prospective studies. The researchers evaluated standalone 29-MHz micro-ultrasound as a way to classify clinically significant prostate cancer. They used histopathology as the reference standard to check the accuracy of the scans. The studies involved patients going through a diagnostic pathway for prostate cancer assessment.

The analysis found that the test had a sensitivity of 0.84. This means it correctly identified most cases of significant cancer. However, the specificity was lower at 0.41. This indicates the test might flag some cases that do not have significant cancer.

The results showed a modest impact on post-test probability. A positive test shifted the probability by about 33 percent, while a negative test shifted it by about 11 percent. The study noted substantial heterogeneity among the studies and that results were influenced by different clinical thresholds.

Readers should understand that this tool works best as a complementary triage or rule-out adjunct. It is particularly useful when mpMRI is unavailable, contraindicated, or delayed. The evidence supports its use in these specific situations, but larger multicenter studies are needed to standardize thresholds and training.

What this means for you:
Micro-ultrasound can help rule out significant prostate cancer when MRI is unavailable or delayed.

Study Details

Study typeMeta analysis
EvidenceLevel 1
PublishedJun 2026
View Original Abstract ↓
BACKGROUND: Micro-ultrasound (micro-US; 29-MHz) offers real-time, high-resolution prostate imaging, but its stand-alone diagnostic accuracy remains uncertain. We synthesized prospective evidence to evaluate micro-US for classifying clinically significant prostate cancer (csPCa) using histopathology as the reference standard. METHODS: We searched PubMed, Embase, Scopus, and Web of Science (inception-20 May 2025) for prospective studies assessing micro-US as an index test on a diagnostic pathway. Data were pooled using random-effects models on logit-transformed sensitivity and specificity, with an HSROC representation and model diagnostics. Subgroup and meta-regression analyses explored heterogeneity, including threshold (PRI-MUS) and spectrum effects. Clinical utility was appraised using Fagan nomograms and a likelihood-ratio scatter. Small-study effects were evaluated with Deeks' test. RESULTS: Five prospective studies met criteria. Pooled sensitivity was 0.84 (95% CI 0.65-0.94) and pooled specificity was 0.41 (95% CI 0.25-0.59), indicating moderate discrimination on HSROC. Secondary metrics were concordant (PLR 1.45, 95% CI 1.17-1.80; NLR 0.37, 95% CI 0.23-0.61; DOR 3.95, 95% CI 2.48-6.30). On a 25% pre-test probability, the Fagan nomogram showed modest shifts (~ 33% after a positive test; ~11% after a negative), supporting a triage/rule-out role. Heterogeneity was substantial and strongly influenced by threshold and clinical spectrum differences; subgroup and meta-regression suggested that spectrum-related factors were associated with lower specificity, whereas no covariate robustly altered sensitivity (exploratory given small k). Model checks were acceptable, and Deeks' test showed no evidence of small-study effects (p ≈ 0.70). CONCLUSION: As a stand-alone index test for csPCa classification, micro-US demonstrates high sensitivity but low specificity, yielding modest impact on post-test probability. These findings support micro-US as a complementary/triage (rule-out) adjunct, particularly when mpMRI is unavailable, contraindicated, or delayed, while highlighting the need for standardized PRI-MUS thresholds, reader training, and larger multicenter studies to refine specificity and clarify integration with MRI-based pathways.
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