Staging of rectal cancer by double-contrast MR imaging using the rectally administered superparamagnetic iron oxide contrast agent ferristene and IV gadodiamide injection: results of a multicenter phase II trial.

The aim of this study was to assess the accuracy of double-contrast magnetic resonance imaging (MRI) with rectal application of the superparamagnetic iron oxide contrast agent (SPIO) ferristene and IV gadodiamide for preoperative staging of rectal cancer. In a randomized phase II dose-ranging trial, 113 patients were studied preoperatively with one of four different formulations of ferristene (Abdoscan) as an enema before MRI. T1-weighted spin-echo (T1w SE) and T2w turbo spin-echo (TSE) single-contrast images were obtained as well as T1w SE and gradient-echo (GRE) double-contrast images after IV gadodiamide injection (Omniscan). Images were assessed qualitatively, and TNM tumor stage was compared with histopathology. High-viscosity ferristene formulations were superior to low-viscosity formulations in tumor staging (accuracy 90% vs 74%, P < 0.01). There was no significant difference between high and low iron content ferristene. MRI had a sensitivity of 97%, specificity of 50%, and accuracy of 82% for staging of rectal carcinoma higher than T2 stage. At receiver operator characteristic (ROC) analysis, MR differentiation between T1/T2 and T3/T4 tumor stages yielded a ROC index of 0.848. Double-contrast MRI is an accurate method for preoperative staging of rectal cancer.

Rectal carcinoma: double-contrast MR imaging for preoperative staging.

PURPOSE: To evaluate and compare the imaging findings and staging of rectal carcinoma by using conventional magnetic resonance (MR) imaging, MR imaging with an enema of superparamagnetic ferristene-based contrast material, and MR imaging with an enema of ferristene solution plus intravenous injection of gadodiamide. MATERIALS AND METHODS: Twenty-nine patients (17 women, 12 men; age range, 39-91 years) referred with a diagnosis of rectal carcinoma were examined. Analysis of the rectal wall and staging of the tumor were performed. In all patients, the MR imaging findings were correlated with the histopathologic findings. RESULTS: The contrast material enema caused distention of the rectum and an intraluminal signal void, whereas the gadodiamide injection caused enhancement of the mucosa on T1-weighted images. This enhancement enabled evaluation of the normal rectal wall and differentiation of the mucosa, tunica muscularis, and perirectal space, which was not possible on the nonenhanced images. Double-contrast (ferristene solution plus gadodiamide) MR imaging was superior to imaging with only ferristene-based contrast material and had a sensitivity of 100%, specificity of 70%, and accuracy of 90% in distinguishing tumor stages worse than Dukes A. CONCLUSION: Double contrast material-enhanced MR imaging enables accurate rectal carcinoma staging, which is not possible at nonenhanced imaging.

Diagnostic efficacy of MnDPDP in MR imaging of the liver. A phase III multicentre study.

PURPOSE: To assess the diagnostic efficacy, safety and tolerability of mangafodipir trisodium (MnDPDP, Teslascan) in MR imaging of the liver. MATERIAL AND METHODS: Eighty-two patients from 4 centres underwent MR imaging with pre-contrast sequences including T1-weighted SE and GRE, and T2-weighted turbo SE sequences. MnDPDP at a dose of 5 mumol/kg b.w. was administered by slow i.v. infusion, and 20-60 min after infusion the T1-weighted SE and GRE sequences were repeated. Diagnostic efficacy was evaluated by counting the number of lesions and by evaluating whether more information for lesion characterisation was available in post-contrast images. Safety and tolerability were assessed by recording adverse events and infusion-related discomfort. RESULTS: Significantly more lesions were found in MnDPDP-enhanced T1-weighted SE and GRE images than in unenhanced images of the same sequences. More lesions were also found in these images compared with T2-weighted images at a level of marginal significance. More information was obtained from MnDPDP-enhanced images in 40 cases. Mild to moderate adverse events were experienced by 17% of the patients. CONCLUSION: MnDPDP-enhanced images can improve lesion detection in the liver and are helpful for lesion characterisation. To obtain optimal diagnostic information of liver lesions T2-weighted images are also valuable. MnDPDP is a safe contrast agent for MR imaging of liver lesions.

Preoperative staging of rectal carcinoma using double-contrast MR imaging. Technical aspects and early clinical experiences.

PURPOSE: To improve preoperative staging of rectal carcinoma with MR imaging, using a double-contrast technique. MATERIAL AND METHODS: Imaging was performed in 12 patients before and after i.v. injection of Gd-DTPA and rectal administration of a superparamagnetic contrast medium, mainly containing magnetite. The diagnostic information was evaluated and compared with findings at surgery and histopathological analysis. RESULTS: The superparamagnetic contrast medium enema caused a distension of the rectum and intraluminal signal void, whereas Gd-DTPA enhanced the mucosa in T1-weighted images. This allowed an evaluation of the normal rectal wall and separation of the mucosa, tunica muscularis and perirectal space in all cases, which was not possible in T1- or T2-weighted precontrast images. The rectal carcinoma could be delineated and tumor invasion to the rectal wall determined in all cases. The findings in postcontrast MR corresponded with the findings at histopathological examination in 11 of 12 patients. The histopathological examination in one patient revealed metastases (< 1 cm) in regional lymph nodes, too small to be identified in pre- or postcontrast MR images. CONCLUSION: Double-contrast-enhanced MR imaging allows evaluation of the normal rectal wall and preoperative staging of rectal carcinoma.

Lymph nodes in the hepato-duodenal ligament. A comparison between ultrasound and low-field MR imaging.

PURPOSE: We investigated whether a low-field MR unit (0.2 T) could demonstrate and determine the size of the lymph nodes in the hepato-duodenal ligament that were previously found on ultrasound. MATERIAL AND METHODS: Eighteen patients were examined with ultrasound, MR and liver biopsy on consecutive days. RESULTS: Two-thirds of the enlarged nodes detected by ultrasound were also detected with the low-field MR technique. However, the size of the nodes was slightly larger on ultrasound. CONCLUSION: Compared to low-field MR, ultrasound appears to be superior in the evaluation of lymph nodes in the liver hilus.

MR imaging of the pancreas at 0.3 T using a super-paramagnetic oral contrast medium.

Twenty patients with carcinoma of the pancreas identified with ultrasonography and/or CT and confirmed by histology, were examined with MR before and after administration of an oral super-paramagnetic contrast medium. Ten patients were examined after administration of the contrast medium through a duodenal tube. Ten patients drank the contrast medium mixed with a viscosity-increasing agent. Organ delineation and diagnostic information were improved in the postcontrast scans in both groups and the viscous contrast suspension yielded better delineation and diagnostic information than the aqueous suspension. The viscous contrast suspension also showed better tolerance, contrast distribution and less artifacts than the aqueous suspension.

Signal alterations, artifacts and image distortion induced by a superparamagnetic contrast medium. A phantom study in a 0.3 tesla MR system.

In a phantom study using a 0.3 tesla MR system the signal alterations, artifacts and image distortion induced by a bowel contrast medium containing superparamagnetic magnetite particles were evaluated. A concentration of 20 mg iron/l was most useful because it caused a significant signal reduction without disturbing artifacts and image distortion. The signal reduction was most pronounced on long TR/TE spin echo sequences. The appearance and distribution of artifacts are related to the direction of the static magnetic field and frequency encoding gradient. The size of artifacts is related to the concentration of the contrast medium and the band width used.

The vertical position of the patella. A new radiographic method for routine use.

Patella height was defined by the distance between the midpoint of the articular surface of the patella and the condylar plane, which was constructed perpendicular to the mechanical axis of the tibia. In two series of normal individuals the measured distances were related to body height and the length of the lower leg and thus expressed as its ratio, which was the same in both sexes. The measurements were performed on lateral radiographs of the knee and lower leg obtained in weight-bearing and 30 degrees to 40 degrees of knee flexion using a simple device to obtain a standardized position of the lower leg during the examination. The standing position is proposed for these measurements since the patellar ligament is shorter in the recumbent position. The method can be used for biomechanical analysis of the femoropatellar joint.