Susanne C. Goehde

Magnetic resonance colonography for the detection of inflammatory diseases of the large bowel: quantifying the inflammatory activity.

Introduction: The purpose of this study was to assess the diagnostic accuracy of magnetic resonance colonography (MRC) for its ability to detect and quantify inflammatory bowel disease (IBD) affecting the colon. Endoscopically obtained histopathology specimens were used as the standard of reference. Materials and methods: Fifteen normal subjects and 23 patients with suspected IBD of the large bowel underwent MRC. Three dimensional T1 weighted data sets were collected following rectal administration of water prior to and 75 seconds after intravenous administration of paramagnetic contrast (gadolinium-BOPTA). The presence of inflammatory changes in patients was documented based on bowel wall contrast enhancement, bowel wall thickness, presence of perifocal lymph nodes, and loss of haustral folds. All four criteria were quantified relative to data obtained from normal subjects and summarised in a single score. This MRC based score was compared with histopathological data based on conventional endoscopic findings. Results: MRC correctly identified 68 of 73 segments found to reveal IBD changes by histopathology. All severely inflamed segments were correctly identified as such and there were no false positive findings. Based on the proposed composite score, MRC detected and characterised clinically relevant IBD of the large bowel with sensitivity and specificity values of 87% and 100%, respectively, for all investigated colonic segments. Conclusion: MRC may be considered a promising alternative to endoscopic biopsy in monitoring IBD activity or assessing therapeutic effectiveness.

Detection of pulmonary nodules using a 2D HASTE MR sequence: comparison with MDCT

OBJECTIVE The objective of our study was to determine the diagnostic performance of MRI based on a HASTE sequence for the detection of pulmonary nodules in comparison with MDCT. MATERIALS AND METHODS Thirty patients with known pulmonary nodules underwent both MRI and CT. CT of the lung served as the standard of reference and was performed on a 4-MDCT scanner using a routine protocol. MRI was performed with axial and coronal HASTE sequences using a high-performance 1.5-T MR scanner. Image data were analyzed in three steps after completion of all data acquisition. Step 1 was the analysis of all the CT image data. Step 2 was the analysis of all the MR image data while blinded to the results of the CT findings. Step 3 closed with a simultaneous review of all corresponding CT and MRI data, including a one-to-one correlation of the size and location of all the nodules that were detected. RESULTS Compared with the sensitivity of CT, the sensitivity values for the HASTE MR sequence were as follows: 73% for lesions less than 3 mm, 86.3% for lesions between 3 and 5 mm, 95.7% for lesions between 6 and 10 mm, and 100% for lesions larger than 10 mm. The overall sensitivity of the HASTE sequence for the detection of all pulmonary lesions was 85.4%. CONCLUSION An MRI examination that consists of a HASTE sequence allows one to detect, exclude, or monitor pulmonary lesions that are 5 mm and bigger. Suspicious lesions smaller than 5 mm still need to be validated using CT.

Real time high resolution magnetic resonance imaging for the assessment of gastric motility disorders

Background: The aim of this study was to evaluate whether patients with increased or decreased gastric motility can be differentiated from healthy volunteers by means of real time magnetic resonance imaging (MRI). Patients and methods: Ten healthy volunteers, 10 patients with gastroparesis, and 10 patients with functional pylorospasm/peptic pyloric stenosis underwent real time MRI. All patients were examined on two separate days; once prior to therapy and once after adequate therapy. Antral motility was quantified by calculating the gastric motility index. Results: Patients with gastroparesis showed a lower motility index compared with the reference volunteer group while the mean motility index of the patient group with pylorospasm was more than three times higher than that of the reference value of the volunteer group. However, the gastric motility index in the patient group with gastroparesis increased, and in the group with functional pylorospasm/peptic pyloric stenosis it decreased significantly after therapy. Conclusion: Real time MRI is a reliable tool for assessment of gastric motion. Furthermore, differences in gastric motility index in patients with increased or decreased gastric motility could be evaluated and quantified. Due to the non-invasive character of MRI, this imaging modality may be an attractive alternative to conventional invasive diagnostic tools for gastric motility disorders and therapeutic monitoring.

MR colonography: How does air compare to water for colonic distention?

To prove the feasibility of air‐distended magnetic resonance colonography (MRC) and compare it with water‐based distention.

Small bowel hydro-MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?

To assess the impact of an additional rectal enema filling in small bowel hydro‐MRI in patients with Crohns disease.

Whole body MR angiography screening.

Lack of side effects, diagnostic accuracy and recent improvements in technology qualify magnetic resonance imaging for preventive cardiovascular imaging. The purpose of this study was to assess the feasibility of a comprehensive contrast-enhanced three-dimensional whole-body MR (magnetic resonance) angiography examination technique using a rolling table platform system with a 1.5-T MR system. The examination yielded diagnostic image quality in 5312 out of 5400 (98.3%) evaluated vascular segments in 180 consecutive patients with peripheral vascular disease. Besides the proved peripheral vascular disease, additional relevant vascular disease was found in 65 vessel segments in 42 patients: carotid artery stenosis (n = 21), subclavian artery stenosis (n = 5), renal artery stenosis (n = 27) abdominal aortic aneurysm (n = 7), aortic dissection (n = 5). In 20 patients additional imaging studies confirmed the results of whole-body MRA without false positive or false negative findings. The described whole-body MR angiography protocol appears well suited for comprehensive evaluation of the arterial system beyond the peripheral vasculature.

Dose optimization of mannitol solution for small bowel distension in MRI.

To optimize the dose of a hydro solution containing 2.5% mannitol and 0.2% locust bean gum (LBG) for small bowel MRI in terms of bowel distension and patient acceptance.

Magnetic resonance colonography: Comparison of contrast-enhanced three-dimensional vibe with two-dimensional FISP sequences: Preliminary experience

Purpose:The purpose of this study was to compare a dark-lumen magnetic resonance colonography (MRC) approach with a True FISP-based bright-lumen technique concerning presence of artifacts and the detection rate of colorectal pathologies. Materials and Methods:Thirty-seven patients with suspected colorectal lesions were included in this trial. The colon was filled with 2500 mL of tap water. Two-dimensional True FISP datasets as well as T1-weighted GRE sequences (pre- and post intravenous contrast) were acquired. The detection rate of colorectal masses and inflammatory lesions was determined for both techniques separately. Besides, image quality was assessed. All patients underwent conventional colonoscopy as the standard of reference. Results:By means of dark-lumen MRC datasets, all polyps >5 mm were correctly diagnosed, whereas 4 polyps <5 mm were missed. Sensitivity of dark-lumen MRC amounted to 78.9%. There were no false-positive results: residual stool could correctly be differentiated from colorectal masses. The True FISP-based bright-lumen MRC, however, failed to detect 2 additional polyps resulting in a sensitivity of 68.4%. Furthermore, bright-lumen MRC led to false-positive results in 5 patients. Both techniques visualized inflammatory bowel disease in 5 patients. However, image quality of True FISP was rated superior to that of dark-lumen MRC. Conclusion:Dark-lumen MRC proved to be superior over bright-lumen MRC regarding the detection of colorectal masses. However, True FISP imaging can turn out to be helpful as a result of high image quality and motion insensitivity.

Fecal tagging: MR colonography without colonic cleansing.

Colorectal cancer, mostly arising (>90%) from preexisting adenomatous polyps, continues to be the second leading cause of cancer death. Magnetic resonance colonography (MRC) permits accurate detection of colonic polyps with a diameter larger than 10 mm. Because residual colonic stool cannot be differentiated from polyps, MRC requires a clean colon. However, the rigors associated with colonic cleansing considerably reduce patient acceptance. The need for colonic cleansing could be eliminated, if stool were to acquire a signal intensity different from polyps and identical to the enema used to fill and distend the colon. In principle, there are two approaches to this concept of fecal tagging: dark polyps surrounded by bright stool and a bright enema, and bright polyps surrounded by dark stool and a dark enema. The first approach has been evaluated with some success. Gadolinium (Gd)–DOTA was administered as an oral contrast agent with meals preceding MRC based on the administration of a Gd-based enema. The high cost of Gd-based contrast has limited the clinical utility of this technique. In the second approach patients are provided with barium as an oral fecal tagging agent to render stool dark, and barium for the enema is used to distend the colon during MRC. The colonic wall and polyps arising from it can be made visible after intravenous administration of Gd-based extracellular contrast. This method provides sufficient contrast between the darkened colonic lumen and the brightly enhanced colonic wall to permit virtual endoscopic rendering. Preliminary results showed an exact correlation with findings of conventional endoscopy and surgery. Fecal tagging obviates bowel cleansing and therefore should enhance patient acceptance for MR colonoscopy. Barium as the tagging agent is promising because it is inexpensive, commercially available, and characterized by an excellent safety profile.

Real‐time high‐resolution MRI for the assessment of gastric motility: Pre‐ and postpharmacological stimuli

To determine the practicality of MRI using a new real‐time sequence for the assessment of gastric motion, and quantify the effects of motility‐modifying substances.