Usefulness of Short TE Proton MR Spectroscopy in Grading Brain Glial Tumors

PURPOSE: To determine the usefulness of in-vivo proton MR spectroscopy (MRS) with short TE for grading glial brain tumors. MATERIALS AND METHODS: For the purpose of tumor grading, 32 patients with pathologically confirmed glial tu-mors were examined by proton MRS. This and MRI were performed on a 1.5 T superconductive MR scanner. T2-weighted FSE images (TR/TE=4,000/100msec) were used to obtain anatomical reference images. The stim-ulated- echo acquisition mode (STEAM: TR/TE/MT=3000/30/13.7msec) was used to acquire MRS data from the localized single-voxel (2 x2 x2 cm 3 ) in both hemispheres. Residual water resonance in the spectra was re-moved using a CHESS pulse sequence. Prior to baseline correction, MRS raw-data, free induction decay sig-nals were zero-filled, apodized by an exponential function with 8Hz line-broadening, and fourier transformed. To normalize signal intensities of metabolites such as N-acetyl aspartate (NAA), total choline (Cho), myo-inosi-tol (mI), and lactate (Lac), the creatine(Cr) peak was used as a standard. RESULTS: The concentration ratios of Cho/Cr, mI/Cr, alpha-Glx, Lac, and NAA/Cr changed linearly according to tu-mor grade. Increased Cho, mI, alpha-Glx, and Lac levels were clearly seen in all grades. The most dramatic in-creases, observed in either Grade III or IV, were 78% and 228% for Cho(p<0.001), 106% and 61% for mI (p<0.001), 32% and 5% for alpha-Glx, and 727% and 450% for Lac (p<0.001), respectively. Increase of concen-tration ratio of Lac/Cr observed only in Grade III and Grade IV. The concentration ratios of NAA/Cr decreased gradually as tumor grade increased(p<0.001). CONCLUSION: The metabolic changes seen on proton MR spectroscopy using short TE might be useful for grad-ing glial brain tumors.

Superselective Embolization with Microcoil in Acute Gastrointestinal Hemorrhage

PURPOSE: To evaluate the efficacy and safety of superselective arterial embolization using the microcoil in acute gastrointestinal hemorrhage. MATERIALS AND METHODS: We evaluated 11 of 42 patients who had undergone diagnostic angiography and tran-scatheter arterial embolization due to acute gastrointestinal hemorrhage and subsequently underwent superselective arterial embolization using the microcoil. Nine were males and two were females, and their age ranged from 33 to 70 (mean, 51) years. The etiologies were bleeding ulcer (n=5), pseudoaneurysm from pancreatitis (n=3), and postoperative bleeding (n=3). The symptoms were melena, hematemesis, and hematochezia, and the critical signs were decreased hemoglobin and worsening of vital signs. All patients underwent superselective embolization using the microcatheter and microcoil. RESULTS: Bleeding occurred in the gastroduodenal artery (n=5), inferior pancreaticoduodenal artery (n=2), left gastric artery (n=2), right hepatic artery (n=1), and ileal branch of the superior mesenteric artery (n=1). All cases were treated succesfully, without complications. In one case in which there was bleeding in the right he-patic artery, reembolization with a microcoil was needed because of persistent melena. During follow up, three patients died from complications arising underlying diseases, namely disseminated intravascular coagulopathy, chronic renal failure, and adult respiratory distress syndrome. Procedural complications, such as ischemia or infarction were not noted. CONCLUSION: Superselective arterial embolization using the microcoil is a safe and effective method for the treatment of acute gastrointestinal bleeding, and does not lead to complications.

The Usefulness of Perfusion MR Imaging in Patients with Brain Tumors

PURPOSE: To determine the usefulness of perfusion weighted MR imaging in the assessment of relative cerebral blood volume(rCBV) in brain tumors. MATERIALS AND METHODS: Twenty-three patients with primary or metastatic brain tumors [nine gliomas (6 high grade and 3 low), six metastatic tumors, five meningiomas (4 benign and 1 atypical), two neurilemmomas and one hemangioblastoma] underwent perfusion-weighted and conventional MR imaging. A total of 240 perfusion MR images were obtained from four axial slices after rapid injection of contrast media using a gradient echo planar imaging pulse sequence, and this was followed by postprocessing of these images to give CBV maps. In order to calculate the rCBV of tumor to normal white matter, ROIs were defined on the CBV map of a tumor and its contralateral normal white matter. RESULTS: The rCBV ratio of tumors to contralateral normal side was as follows: high-grade glioma, 0.40-5.64(mean +/-SD = 2.91 0.95); low grade astrocytoma, 0.77 -1.66 (mean +/-SD = 1.15 +/-0.28); benign menin-gioma,2.06 -4.90 (mean +/-SD = 3.59 +/-0.84); atypical meningioma, 0.46 -1.18 (mean +/-SD = 0.72 +/-0.25); neurilemmoma, 1.45 -3.85 (mean +/-SD = 2.56 +/-0.92); and hemangioblastoma, 6.16 -8.35 (mean +/-SD = 7.02 +/-1.12). High grade gliomas were more hypervascular than low grade astrocytomas, and showed a variable range of relative cerebral blood volume. In metaststic cancer, CBV maps showed a relatively high and variable blood volume. Benign meningiomas exhibited high relative cerebral blood volume, while in the atypical meningioma with cystic degeneration, this volume was low. In neurilemmomas, a variable range of relative cerebral blood volume, was noted, while in the mural nodule of the hemangioblastoma, this volume was the highest. CONCLUSION: Perfusion-weighted MRI indicated the rCBV of various brain tumor lesions, and this suggests that the modality can provide a very useful means of assessing brain tumor vascularity.

The Usefulness of CT and MR Virtual Colonoscopy in the Evaluation of Experimental Polyp Models

PURPOSE: The purpose of this study was to evaluate the diagnostic accuracy of CT and MR virtual colonoscopy using an experimental model of colonic polyposis. MATERIALS AND METHODS: Eleven pig colons ranging from 15 to 20cm in length were cleansed and a total of 99 variable sized polyps ranging from 3 to 15mm in diameter were created. The polyps were divided into three groups according to size: <5mm(n=23), 5-9mm(n=44), and ?10mm(n=32) in diameter. Each specimen was scanned using spiral CT and MRI. Each CT and MR virtual colonoscopy was independently evaluated by two radiologists blinded to the location, size and numbers of polyps, but aware that polyps were present. Interobserver agreement regarding the detection rate of the polyps during the two types of virtual colonoscopy was measured and the diagnostic accuracy of CT and MR virtual colonoscopy was compared. Results: In both CT and MR virtual colonoscopy, the detection rates determined by the two radiologists coincided in all three groups(p<0.05). The detection rates of polyps less than 5mm, between 5 and 9mm, and 10mm or larger in diameter were 74%(17/23), 89%(39/44), and 100%(32/32), respectively, in CT colonoscopy, and 61%(14/23), 89%(39/44), and 100%(32/32), respectively in MR colonoscopy. In polyps 5mm or larger, the results of the two types of virtual colonscopy coincided but in those less than 5mm in diameter, the results of MR virtual colonoscopy were slightly inferior to those of CT colonoscopy. Conclusion: Both CT and MR virtual colonoscopy provide high detection rates of colonic polyps 5mm or larger in diameter and these techniques can therefore be used to diagnose colonic mass lesions.

The Usefulness of CT and MR Virtual Colonoscopy in the Evaluation of Experimental Polyp Models

PURPOSE: The purpose of this study was to evaluate the diagnostic accuracy of CT and MR virtual colonoscopy using an experimental model of colonic polyposis. MATERIALS AND METHODS: Eleven pig colons ranging from 15 to 20cm in length were cleansed and a total of 99 variable sized polyps ranging from 3 to 15mm in diameter were created. The polyps were divided into three groups according to size: <5mm(n=23), 5-9mm(n=44), and ?10mm(n=32) in diameter. Each specimen was scanned using spiral CT and MRI. Each CT and MR virtual colonoscopy was independently evaluated by two radiologists blinded to the location, size and numbers of polyps, but aware that polyps were present. Interobserver agreement regarding the detection rate of the polyps during the two types of virtual colonoscopy was measured and the diagnostic accuracy of CT and MR virtual colonoscopy was compared. Results: In both CT and MR virtual colonoscopy, the detection rates determined by the two radiologists coincided in all three groups(p<0.05). The detection rates of polyps less than 5mm, between 5 and 9mm, and 10mm or larger in diameter were 74%(17/23), 89%(39/44), and 100%(32/32), respectively, in CT colonoscopy, and 61%(14/23), 89%(39/44), and 100%(32/32), respectively in MR colonoscopy. In polyps 5mm or larger, the results of the two types of virtual colonscopy coincided but in those less than 5mm in diameter, the results of MR virtual colonoscopy were slightly inferior to those of CT colonoscopy. Conclusion: Both CT and MR virtual colonoscopy provide high detection rates of colonic polyps 5mm or larger in diameter and these techniques can therefore be used to diagnose colonic mass lesions.