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In the UMC Utrecht a prototype MRI accelerator has been installed to investigate the feasibility of real-time, MRI guided radiotherapy. The system consists of a 6 MV Elekta (Crawley, UK) accelerator and a 1.5 T Philips (Best, The Netherlands) MRI system. The system is installed in a standard radiotherapy bunker. The bunker is at the corner of a block of six bunkers, so there are three neighbouring clinical Elekta accelerators. During ramping of the magnet, the magnetic fringe field in the two nearest bunkers was measured as a function of the magnetic field strength of the MRI magnet. At 8 m, a maximum increase of 1.5 G was measured, at 12 m, 0.6 G. This is up to three times the earth's magnetic field. The clinical accelerators are needed to be re-calibrated in order to operate in such an external magnetic field. The resulting radiation field flatness of the clinical accelerators was measured and was similar to the situation before ramping the magnet. [ABSTRACT FROM AUTHOR]

Background: Alosetron is a 5-hydroxytryptamine-3 receptor antagonist reducing symptoms in female patients with diarrhoea-predominant irritable bowel syndrome, and is known to increase the colonic transit time. Aim: To study the effect of alosetron on left colonic phasic motility in ambulant non-constipated patients with irritable bowel syndrome and healthy volunteers. Methods: In a double-blind, randomized, crossover design, 10 patients with irritable bowel syndrome and 12 sex- and age-matched volunteers were treated for two 7-day periods with alosetron, 4 mg b.d., or placebo b.d. On day 6 of each treatment period, a six-channel solid-state manometric catheter was positioned in the left colon and 24 h motility was studied on day 7. The periprandial phasic motility around dinnertime was evaluated in the descending and sigmoid colon. The high-amplitude propagated contraction frequency and characteristics were calculated. Results: Alosetron appeared to increase the overall periprandial frequency in the sigmoid colon (P =0.043) and the mean amplitude of colonic contractions in the descending colon (P =0.007). The high-amplitude propagated contraction frequency was higher on alosetron during the second half of the day for patients with irritable bowel syndrome (P =0.002), with increased mean propagation length of high-amplitude propagated contractions (P =0.001). The stool frequency (P =0.024) and stool consistency score (P =0.002) were decreased by alosetron. Conclusions: The 5-hydroxytryptamine-3 receptor antagonist alosetron marginally increased left colonic periprandial phasic motility. Alosetron increased the number and propagation length of high-amplitude propagated contractions, which were paradoxically accompanied by a decrease in stool frequency and a firming of stool consistency. [ABSTRACT FROM AUTHOR]

Background: Extremely dense breast tissue is a risk factor for breast cancer and limits the detection of cancer with mammography. Data are needed on the use of supplemental magnetic resonance imaging (MRI) to improve early detection and reduce interval breast cancers in such patients.Methods: In this multicenter, randomized, controlled trial in the Netherlands, we assigned 40,373 women between the ages of 50 and 75 years with extremely dense breast tissue and normal results on screening mammography to a group that was invited to undergo supplemental MRI or to a group that received mammography screening only. The groups were assigned in a 1:4 ratio, with 8061 in the MRI-invitation group and 32,312 in the mammography-only group. The primary outcome was the between-group difference in the incidence of interval cancers during a 2-year screening period.Results: The interval-cancer rate was 2.5 per 1000 screenings in the MRI-invitation group and 5.0 per 1000 screenings in the mammography-only group, for a difference of 2.5 per 1000 screenings (95% confidence interval [CI], 1.0 to 3.7; P<0.001). Of the women who were invited to undergo MRI, 59% accepted the invitation. Of the 20 interval cancers that were diagnosed in the MRI-invitation group, 4 were diagnosed in the women who actually underwent MRI (0.8 per 1000 screenings) and 16 in those who did not accept the invitation (4.9 per 1000 screenings). The MRI cancer-detection rate among the women who actually underwent MRI screening was 16.5 per 1000 screenings (95% CI, 13.3 to 20.5). The positive predictive value was 17.4% (95% CI, 14.2 to 21.2) for recall for additional testing and 26.3% (95% CI, 21.7 to 31.6) for biopsy. The false positive rate was 79.8 per 1000 screenings. Among the women who underwent MRI, 0.1% had either an adverse event or a serious adverse event during or immediately after the screening.Conclusions: The use of supplemental MRI screening in women with extremely dense breast tissue and normal results on mammography resulted in the diagnosis of significantly fewer interval cancers than mammography alone during a 2-year screening period. (Funded by the University Medical Center Utrecht and others; DENSE ClinicalTrials.gov number, NCT01315015.). [ABSTRACT FROM AUTHOR]