The role of perfusion effects in monitoring of chemoradiotherapy of rectal carcinoma using diffusion-weighted imaging.

PURPOSE: The aim of this study was to characterize and understand the therapy-induced changes in diffusion parameters in rectal carcinoma under chemoradiotherapy (CRT). The current literature shows conflicting results in this regard. We applied the intravoxel incoherent motion model, which allows for the differentiation between diffusion (D) and perfusion (f) effects, to further elucidate potential underlying causes for these divergent reports. MATERIALS AND METHODS: Eighteen patients with primary rectal carcinoma undergoing preoperative CRT were examined before, during, and after neoadjuvant CRT using diffusion-weighted imaging. Using the intravoxel incoherent motion approach, f and D were extracted and compared with postoperative tumor downstaging and volume. RESULTS: Initial diffusion-derived parameters were within a narrow range (D1 = 0.94 ± 0.12 × 10(-3) mm(2)/s). At follow-up, D rose significantly (D2 = 1.18 ± 0.13 × 10(-3) mm(2)/s; P < 0.0001) and continued to increase significantly after CRT (D3 = 1.24 ± 0.14 × 10(-3) mm(2)/s; P < 0.0001). The perfusion fraction f did not change significantly (f1 = 9.4 ± 2.0%, f2 = 9.4 ± 1.7%, f3 = 9.5 ± 2.7%). Mean volume (V) decreased significantly (V1 = 16,992 ± 13,083 mm(3); V2 = 12,793 ± 8317 mm(3), V3 = 9718 ± 6154 mm(3)). T-downstaging (10:18 patients) showed no significant correlation with diffusion-derived parameters. CONCLUSIONS: Conflicting results in the literature considering apparent diffusion coefficient (ADC) changes in rectal carcinoma under CRT for patients showing T-downstaging are unlikely to be due to perfusion effects. Our data support the view that under effective therapy, an increase in D/ADC can be observed.

Evaluation of bowel peristalsis by dynamic cine MRI: detection of relevant functional disturbances--initial experience.

PURPOSE: To investigate the diagnostic performance of a cine magnetic resonance imaging (MRI) sequence in the visualization and detection of impaired bowel peristalsis. MATERIALS AND METHODS: In all, 91 consecutive patients (mean age 45 years) were prospectively examined on a 1.5 T system and stratified into a surgery group (n = 22) and a nonsurgery group (n = 69). A coronal fast imaging with steady-state precession (TrueFISP) sequence with 30 acquisitions per slice covered the abdomen in 10-15 slices each 7-12 mm thick (temporal resolution: 6-8 sec per frame). Image evaluation for reduced bowel peristalsis and relevant bowel stenosis was compared to surgical findings or clinical follow-up. RESULTS: Cine MRI reached 96% accuracy (94% sensitivity; 100% specificity) in detecting a relevant reduction in bowel peristalsis and 85% of relevant stenosis was identified in the surgery group. Twenty of 69 patients of the nonsurgery group showed reduced peristalsis on cine MR which was attributed to underlying disease; 49/69 patients in this group had no findings on cine MR and were uneventfully followed up. CONCLUSION: Cine MRI of the bowel provides functional information of bowel passage. The visualization of a reduction in peristalsis may improve the assessment of the functional impact of suspected bowel adhesions or stenosis. Standard bowel MR protocols can be easily complemented by cine MR, extending scan time by <4 minutes.

Influence of intraoperative and postoperative radiotherapy on functional outcome in patients undergoing standard and deep anterior resection for rectal cancer.

PURPOSE: This study was designed to investigate the influence of intraoperative and postoperative radiotherapy on functional outcome after rectal resection for rectal cancer. METHODS: One hundred patients who underwent deep or standard anterior resection for rectal cancer were included in this follow-up study. All patients filled out questionnaires regarding morbidity and functional outcome; a subgroup (n = 63) underwent further clinical evaluation. The results were stratified according to radiation: Group I, no radiation (n = 37); Group II, only intraoperative radiation (n = 12); Group III, intraoperative and postoperative radiation (n = 51). RESULTS: Anal continence measured by Kirwan-Parks classification and Wexner score was significantly different within the three groups (P < 0.005, P < 0.0001), whereas continence impairment was least in Group I and greatest in Group III. Patients in Group III demonstrated a significantly worsecategory in the Kirwan-Parks classification and worse Wexner scores compared with patients in Group I (P < 0.0001). Patients only having undergone intraoperative radiotherapy had a significantly worse continence (Kirwan-Parks classification) than patients without any radiotherapy (P < 0.05). More patients after intraoperative and postoperative radiation therapy complained of fragmented stools (P < 0.05) and urgency (P < 0.05) compared with patients only having undergone surgery; the need to wear pads was higher (P = 0.001). Vector volume manometry revealed better resting sphincter function in Group I compared with Group III (P < or = 0.005). CONCLUSIONS: Patients with anterior resection for rectal cancer who undergo full-dose radiotherapy have significantly more impairment of anorectal function than patients without radiotherapy. Patients who were only exposed to intraoperative radiotherapy showed moderate impairment of continence function, suggesting that the influence of radiotherapy on anal function may be dose-dependent and application-dependent.