Multi-echo gradient recalled echo imaging of the pelvis for improved depiction of brachytherapy seeds and fiducial markers facilitating radiotherapy planning and treatment of prostatic carcinoma.

PURPOSE: MR localization of implanted devices for radiotherapy (RT) in prostatic carcinoma is critical for treatment planning. This clinical note studies the application of a multi-echo gradient recalled echo (GRE) pulse sequence with sum of squares echo combination (ME GRE) to enhance detection of seeds and fiducials. MATERIALS AND METHODS: Fifteen patients who underwent MRI using fast spin echo (FSE), single-echo and ME GRE over a 9-month period were retrospectively evaluated by two readers who assessed overall image quality, depiction of seeds/fiducials and image sharpness using a 5-point scale (1 = poor, 2 = suboptimal, 3 = adequate, 4 = above average, 5 = excellent). Image scores were compared using the Wilcoxon sign rank test. RESULTS: In all 15 patients, both readers rated the depiction of seeds/fiducials with ME GRE as excellent. In all 15 patients, overall image quality and image sharpness with ME GRE was rated as excellent by reader 1. In 12/15 patients, overall image quality and image sharpness with ME GRE was rated as excellent and in the other patients above average by reader 2. There was a difference in depiction of seeds/fiducials comparing GRE to FSE (P < 0.001) and ME to single echo GRE (P < 0.001). Overall image quality and sharpness was higher with ME compared with single echo GRE (P < 0.001) and similar to FSE (P = 0.26 and P = 0.16). CONCLUSION: Multi-echo GRE provides better detection of implanted seeds and fiducial markers when compared with both FSE and single-echo GRE potentially improving RT treatment planning for prostate carcinoma.

Multi-modality organ-based approach to expected imaging findings, complications and recurrent tumour in the genitourinary tract after radiotherapy.

PURPOSE: Radiotherapy (RT) is an integral component in the management of many abdominal and pelvic malignancies. Imaging follow-up in patients who have received RT is performed to assess for treatment response, evaluate for tumour recurrence and to diagnose complications related to treatment. The purpose of this pictorial review is to depict the expected imaging findings and potential complications following RT in the genitourinary (GU) tract using an organ-based approach and to review the diagnosis of locally recurrent tumour in the GU tract following RT. CONCLUSIONS: Some GU malignancies, namely cervical and prostatic carcinoma, can be treated with radical RT with intent to cure. More frequently, the GU tract is indirectly treated as a result of RT to adjacent cancers. Expected imaging findings, RT-related complications and the diagnosis of recurrent tumour following RT in the GU tract often necessitate a multi-modality imaging approach, the incorporation of functional imaging techniques and an organ-based approach for diagnosis.

Creation of 3-dimensional prostate cancer maps: methodology and clinical and research implications.

CONTEXT: The creation of 3-dimensional prostate cancer maps could assist with surgical intervention, radiotherapy treatment planning and for correlative pathology-imaging research. OBJECTIVES: To develop methodology for creating detailed, 3-dimensional, prostate cancer maps (3DPCM) of tumor location, extra prostatic extension sites, and positive margins and to assess the adequacy of current clinical target volumes for postoperative radiotherapy to the prostate using 3DPCM coregistered with preoperative magnetic resonance imaging. DESIGN: Parallel slices of prostatectomy specimens were created with ProCUT, and 2-dimensional cancer maps were generated as line diagrams after microscopic examination of each slice. The 2-dimensional cancer maps were aligned and stacked to create a 3DPCM, which was coregistered with the preoperative magnetic resonance imaging scan. The map was exported to the radiotherapy planning system and was used to determine the areas at greater risk, which were then compared against the current Radiation Therapy Oncology Group guidelines for contouring postoperative clinical target volumes to assess the adequacy of coverage. RESULTS: Twenty-eight patients with a mean age of 66 years (range, 52-73) underwent radical prostatectomy and postoperative radiotherapy. Seventeen patients (61%) received adjuvant radiotherapy for pT3 disease and/or positive margins, and the rest underwent salvage radiotherapy. Thirty-nine percent (11 of 28) of the patients had Gleason scores of 8 or 9. The contours based on the Radiation Therapy Oncology Group guidelines for postoperative radiotherapy resulted in inadequate coverage of extraprostatic extensions in 79% (22 of 28) and positive margins in 64% (18 of 28) of the cases. CONCLUSIONS: We have developed a methodology for creation of 3DPCM. Modification of the radiotherapy contours, based on the 3DPCM coregistered with pretreatment magnetic resonance imaging, covers the areas at high risk of recurrence. The 3DPCM could become an important clinical and research tool for urologists, pathologists, radiologists, and oncologists.