Does a cleansing enema improve image quality of 3T surface coil multiparametric prostate MRI?

PURPOSE

To assesses the utility of a preparatory enema in the interpretation of prostate multiparametric (MP) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Under a waiver from the Institutional Review Board (IRB), 32 patients without bowel preparation and 28 patients who underwent a self-administered enema were imaged consecutively with 3T MP-MRI over 6 months. Two blinded radiologists independently assessed image quality on T2 -weighted (T2 W), trace b 1000 mm(2) /sec echo-planar (EPI) and apparent-diffusion coefficient (ADC) and assessed for motion/blur on T2 W and distortion/blur on EPI and ADC. Radiologists also quantified rectal stool and gas. A third blinded radiologist generated contrast curves from dynamic contrast-enhanced (DCE) data at six locations and measured the number of corrupted data points, defined as >10% aberrant signal intensity change. Subjective scores were compared using Wilcoxon sign rank test. Rectal contents were correlated to artifact using Spearman correlation. Contrast curves were evaluated with independent t-tests.

RESULTS

There was no difference in image quality on T2 W (P = 0.66-0.74), EPI (P = 0.13-0.36) or ADC (P = 0.49-0.59). There was less rectal stool in the enema group (P = 0.004) and amount of stool correlated with motion artifact on T2 W (r = 0.23, P = 0.02); however, there was no difference in motion artifact between groups (P = 0.47-0.94). Only a minority of patients in the non-enema group had moderate or large amounts of stool (16%) and none of these patients had severe or extensive artifact on T2 . There was less rectal gas in the enema group (P = 0.002); however, amount of gas did not correlate with distortion artifact on EPI or ADC (P = 0.17-0.41) and there was no difference in blur (P = 0.41-0.91) or distortion (P = 0.31-0.99) on EPI or ADC between groups. There was no difference in corrupted data points on DCE (P = 0.46).

CONCLUSION

In this study the use of a preparatory enema did not improve image quality or reduce artifact in prostate MP-MRI.

Multiparametric MRI for localized prostate cancer: lesion detection and staging

Multiparametric MRI of the prostate combines high-resolution anatomic imaging with functional imaging of alterations in normal tissue caused by neoplastic transformation for the identification and characterization of in situ prostate cancer. Lesion detection relies on a systematic approach to the analysis of both anatomic and functional imaging using established criteria for the delineation of suspicious areas. Staging includes visual and functional analysis of the prostate "capsule" to determine if in situ disease is, in fact, organ-confined, as well as the evaluation of pelvic structures including lymph nodes and bones for the detection of metastasis. Although intertwined, the protocol can be optimized depending on whether lesion detection or staging is of the highest priority.

Prostate cancer and its mimics at multiparametric prostate MRI

One in six males will develop prostate cancer during their lifetime. Prostate cancer is the second leading cause of cancer death in American males, behind only lung cancer. Unfortunately, even though this disease is so common, clinical screening methods such as prostate-specific antigen test and transrectal ultrasound-guided prostate biopsy lack sensitivity and specificity in diagnosing prostate cancer. In recent years, multiparametric prostate MRI has emerged as a very important tool in the diagnosis of prostate carcinoma with a high accuracy. However, diagnostic difficulty is often encountered even with an experienced abdominal radiologist. That is mainly because many normal and abnormal entities can mimic prostate carcinoma at multiparametric MRI. Therefore, the purpose of this pictorial review is to discuss the usefulness of multiparametric prostate MRI in the diagnosis of prostate carcinoma, emphasizing the key MRI features that help to make a distinction of prostate carcinoma from its mimics.