Assessing a variety of key considerations in prostate cancer imaging with MRI, the authors of a new review emphasize a reevaluation of specificity with respect to its impact with extraprostatic extension (EPE) prediction and correlation with long-term outcomes.
Here are five pertinent takeaways from the prostate MRI review, which was recently published in the European Journal of Radiology.
- Is tumor diameter or tumor volume a better predictor for EPE? While a recent meta-analysis revealed comparable specificity at 75 percent for tumor diameter vs. 72 percent for tumor volume, researchers pointed out a 15 percent higher sensitivity rate (77 percent vs. 62 percent) and 8 percent higher AUC for tumor volume prediction of EPE.
Emphasizing that tumor volume offers a better indication of the “overall burden and spatial extent of disease,” the review authors noted that each 1 mL increase in volume has been correlated to a 22 percent increase in risk for future metastatic disease over a five-year period for patients with localized PCa.
The above MRI case involved a PI-RADS 5 presentation with extraprostatic extension (EPE). The authors of a new prostate MRI review emphasize a closer look at the impact of specificity and its impact on EPE prediction. (Images courtesy of RSNA.)
2. Can neurovascular bundle asymmetry (NVB) improve clarity with ambiguous PCa cases? While neurovascular bundle asymmetry (NVB) is commonly excluded from MRI scoring systems due to poor inter-reader reproducibility and sensitivity rates ranging between 20 to 30 percent, multiple studies have noted higher than 95 percent specificity for EPE, according to the review authors.
“ … When clearly present, NVB asymmetry can serve as a valuable confirmatory finding in otherwise ambiguous cases, supporting a specificity-focused approach that (prioritizes) avoiding overtreatment rather than pursuing equivocal signs of disease,” wrote lead review author George Agrotis, M.D., Ph.D., who is affiliated with the Netherlands Cancer Institute in Amsterdam, Netherlands, and colleagues.
3. Does the capsular contrast enhancement sign (CES) have prognostic implications for EPE? The review authors acknowledged the rare nature of CES (presenting in 10 percent of patients with PCa) and reported sensitivity, ranging from low (17 percent) to moderate (55 percent), for EPE. However, they also noted specificity ranging from 87 to 100 percent and significant correlation with higher ISUP grade (> 4), lymphovascular invasion and perineural invasion.
“These findings position CES as a highly specific, reproducible, and visually distinctive MRI marker, particularly valuable in posterior peripheral zone tumors,” emphasized Agrotis and colleagues. “Despite its limitations — such as the paucity of studies investigating this imaging finding and its rarity resulting in low sensitivity and generalizability, it serves as a strong rule-in sign of EPE and may offer important prognostic information.
4. Assessing the role of frank EPE. Characterized by MRI findings such as capsular breach, fat plane obliteration, periprostatic tumor mass or direct invasion of neighboring structures, frank EPE has low sensitivity and occurs in less than 15 percent of PCa cases.
However, the review authors maintained that frank EPE offers nearly perfect specificity and inter-reader concurrence for T3a disease.
“While an uncommon imaging feature, (the presence of frank EPE) should guide staging and surgical planning with high confidence,” maintained Agrotis and colleagues.
5. How significant is PCa tumor zone location with EPE? In cases involving tumor capsule contact length (TCCL) ranging between 1 to 20 mm, the review authors noted research demonstrating a 25 percent lower rate of EPE with anterior prostate tumors in comparison to posterior prostate tumors (28 percent vs. 53 percent).
However, the researchers also acknowledged a higher rate of positive surgical margins (PSMs) with anterior prostate tumors. Deficiency of the prostatic pseudocapsule at the apex is a key consideration in these cases, according to the review authors.
While noting moderate sensitivity, the researchers cited research showing that radiological apical tumor involvement (radATI) has over 3.5 times the risk for apical PSM and over a sixfold higher risk for biochemical recurrence.
“While anterior tumors overall are less likely to exhibit capsular breach, MRI features such as tumor contact length still hold predictive value and warrant careful preoperative evaluation due to the increased risk of apical positive surgical margins and adverse oncologic outcomes,” added Agrotis and colleagues.