How well can MRI detect lymph node metastasis in patients with bladder and prostate cancer?

MRI can detect lymph node (LN) metastasis in patients with bladder and prostate cancer with high specificity, but its sensitivity is “poor and heterogeneous,” according to systematic review published in the American Journal of Roentgenology. Using ultrasmall superparamagnetic particles of iron oxide (USPIO) is one way providers can improve sensitivity.

"Notable advances” have been made in MRI solutions in recent years, including USPIO, and the authors wanted to see if the overall performance of MRI for detecting LN metastasis in patients with bladder and prostate cancer had improved as a result.

The authors included 24 studies in their detailed analysis and came up with a pooled per-patient sensitivity of 0.56 and a pooled per-patient specificity of 0.94. In addition, they noted “substantial heterogeneity” as a result of such factors as the type of cancer and the use of USPIO.

“Despite such heterogeneity due to various factors, it is important to note that the specificity remained high in all subgroups and for the overall pooled estimates,” wrote lead author Sang Youn Kim, with the department of radiology at Seoul National University College of Medicine in Seoul, South Korea, and colleagues.

Studies using USPIO, the authors added, had higher sensitivity (0.86) than those that did not (0.46).

“In contrast with the conventional method for assessing LN metastasis—that is, evaluating the shape (round vs oval) and size (i.e., less than mm in short-axis diameter)—MRI using USPIO may be a better technique for detecting metastases in normal-sized LNs,” the authors wrote.