Gin Chung Liu

MRI manifestations of gastrointestinal lymphoma

The magnetic resonance (MR) images of 11 cases of gastrointestinal lymphoma are presented. The findings include irregularly thickened mucosal folds, irregular submucosal infiltration, annular constricting lesion, exophytic tumor growth, mesenteric masses, and mesenteric/retroperitoneal lymphadenopathy. The tumors were homogeneous and intermediate in signal intensity on T1-weighted images. Heterogeneously increased signal intensities were noted on T2-weighted images. There was mild to moderate enhancement after intravenous administration of gadolinium dimeglumine (Gd-DTPA). The submucosal tumor infiltration might be outlined between the strongly GD-DTPA-enhanced mucosa and the low-intensity muscular layer. In one case that received tumor resection, the pathological examination showed destruction of most parts of the muscular layer, and the MR images did not disclose the low intensity muscular zone.

CT appearance of ectopic pancreas: a case report

Abstract. The appearance of ectopic pancreas on computed tomography (CT) is described in a 47-year-old man with bowel obstruction. The enhancement pattern of ectopic pancreas after intravenous iodine contrast administration is the same as that of leiomyoma or carcinoid. This CT finding has not been reported previously to our knowledge.

MRI manifestations of gastrointestinal wall thickening

The appearance of gastrointestinal wall thickening of various entities is demonstrated on magnetic resonance imaging (MRI). The entities include benign gastric ulcer, gastric carcinoma, pancreatic carcinoma with direct invasion of stomach, duodenal leiomyoma, radiation enteritis, peritonitis, colonic carcinoma, recurrent carcinoma at the gastrojejunal anastomosis with direct extension to the transverse colon, colocolic intussusception, sigmoid diverticulitis with pericolonic abscess and fistula into the urinary bladder, and lymphoma of the stomach, duodenum, small bowel, and colon. Air was introduced antegradedly or retrogradedly into the alimentary tract to act as a contrast agent. When the bowel was distended by air, the normal bowel wall was barely visible or even invisible. Abnormal focal or segmental wall thickening was outlined between the intraluminal air and extraluminal fat. In some instances, the thickenings were better demonstrated on coronal or sagittal sections. The proper muscular layer of the bowel has a low-signal intensity and was delineated between the thickened mucosa—submucosa and extramural fat. Interruption of this low-intensity zone might represent tumor invasion through the muscular layer.

MRI demonstration of peritoneal implants

The magnetic resonance imaging (MRI) findings of 12 proven cases of peritoneal implants, mainly carcinomatosis, were reviewed for evidence of peritoneal seedings. The seeded sites include the pouch of Douglas, the ileocecal and retrocecal regions, the right and left paracolic gutters, Morisons pouch, the right subdiaphragmatic parietal peritoneum, the greater and lesser omentum, the gastrocolic, gastrosplenic, and phrenicocolic ligaments, the small bowel mesentery, the sigmoid and transverse mesocolons, and the small and large bowel walls. Sizes varied from less than 1 cm to omental cake and bulky tumors. The findings include linear or tiny nodular infiltrations of the omentum and subperitoneal fat (ligamentous, mesenteric, and mesocolic), focal or segmental wall thickenings, loss of unilateral colonie haustration with sacculation on the contralateral side, and nodular soft tissue masses along different locations of the peritoneal surfaces. Air was introduced via an antegrade or retrograde method to act as a gastrointestinal contrast agent and was found to be useful for delineating the seedings. As is true with computed tomography scan, miliary implants are also not detectable with MRI. The sensitivity and specificity of MRI in detecting peritoneal implants remain to be determined.

Dynamic Contrast-Enhanced Subtraction and Delayed MRI of Gastric Tumors: Radiologic-Pathologic Correlation

Purpose Our goal was to determine whether dynamic MR subtraction images could be used to detect and stage gastric tumors. Method Dynamic MR subtraction images were prospectively performed in 20 patients without gastric lesions and in 39 patients with gastric tumors. The flat-or depressed-type early gastric cancers were excluded. The MR findings were assessed for layered pattern of the normal gastric wall, detectability of tumors, enhanced pattern of tumor, and depth of the tumor invasion. Surgical specimens were obtained from 30 of the patients with tumors, and histopathologic sections were made in the dynamic MR scanning direction. Results The three-layered structure of the normal gastric wall was apparent in more of the dynamic MR subtraction images (60%) than of the nonsubtraction images (30%) in the control group. All 39 gastric tumors were detected by MRI. The intact inner layers overlying stromal tumors and outer layers interrupted by advanced gastric cancers were clear on the subtracted images. MRI accurately T-staged 88% of the gastric cancers. Conclusion Dynamic MR subtraction images can be used to identify gastric tumors and to stage gastric cancers.

Longitudinally monitoring chemotherapy effect of malignant musculoskeletal tumors with in vivo proton magnetic resonance spectroscopy: an initial experience.

Purpose: To investigate the value of in vivo proton (1H) magnetic resonance spectroscopy (MRS) in longitudinally monitoring the treatment response of malignant musculoskeletal tumors under chemotherapy. Materials and Methods: Twenty-three studies in 3 patients with bone and soft-tissue tumors (2 lymphomas and 1 alveolar soft part sarcoma) were included in the study. The dynamic contrast-enhanced magnetic resonance (MR) imaging and single-voxel proton MRS with 135 milliseconds of echo time were carried out using a whole-body 1.5-T scanner and a surface coil. The volume of interest within the lesion was positioned on the area of early enhancement according to the finding of the first dynamic contrast-enhanced MR imaging with subtraction. The choline and water intensities were measured at the peak areas at 3.2 and 4.5 ppm. The choline-water ratios were calculated as well. Statistical analysis was performed by using Kruskal-Wallis 1-way analysis of variance test (Table 1). TABLE 1. Summary of MRS Findings of the 23 Follow-Up Studies in the 3 Patients Results The changes observed on the dynamic contrast-enhanced MR images and tumor size after chemotherapy fell into 2 clearly distinct patterns: subsequent partial response (patients 1 and 2) and progressive disease (patient 3). The choline concentration, choline-volume ratio, and choline-water ratio in the first 2 patients were reduced substantially to zero in the follow-up MRS. In the remaining patient, the choline, choline-volume ratio, and choline-water ratio remained high in the follow-up MRS. The water concentration and water-volume ratio between the 3 patients showed significant statistical differences (Kruskal-Wallis test, P = 0.004 and 0.039). Conclusion In vivo proton MRS is technically feasible for the evaluation of musculoskeletal tumors. Choline can be detected in malignant bone and soft-tissue tumors, and the early metabolite changes after chemotherapy can also be identified in the in vivo proton MRS by using a standard clinical-use 1.5-T MR scanner and a surface coil. The decline of choline after treatment in malignant bone and soft-tissue tumors correlates with the response of the dynamic contrast MR images and the tumor size. The information provided with MR imaging and proton MRS may improve the diagnostic specificity of MR examination in the follow-up of tumor treatment.

MRI manifestations of peritoneal carcinomatosis

Three cases of proved peritoneal carcinomatosis were examined by magnetic resonance imaging (MRI). Air was used to distend the entire gastrointestinal tract via an antegrade method. The findings included seedings along the small intestine, transverse and sigmoid colon, stellate pattern in the mesentery, plaque-like and bulky tumor masses in the mesentery and greater omentum, and focal thickenings along the right subdiaphragmatic parietal peritoneum. Stenosis caused by tumor encasement at the duodenojejunal junction and ileocolic anastomosis were first detected by MRI and later confirmed by barium studies. Ascites was present in all cases. One case showed ascites located only along the left paracolic gutter. This report shows that MRI is also able to demonstrate peritoneal carcinomatosis by using air as a gastrointestinal contrast medium.

A case report of an unusual location of pericruciate meniscal cyst with adjacent bony erosion

Meniscal cysts are uncommon cystic lesions around the knee, and pericruciate meniscal cysts are the most rare types. Here we present an unusual case of a pericruciate meniscal cyst located laterally to the anterior cruciate ligament (ACL), causing erosion of the adjacent tibial plateau.

Clinical application of in vivo proton (1H) MR spectroscopy in musculoskeletal tumors

A technique called in vivo magnetic resonance spectroscopy (MRS) can be performed along with magnetic resonance imaging (MRI) to obtain information about the chemical content of musculoskeletal lesions. This information can be used for several clinical applications, such as improving the accuracy of lesion diagnosis and monitoring the response to cancer therapies. Initial MRS studies of musculoskeletal tumors show promising results, and the technique has been incorporating into the MRI routine protocols. This article introduces 1 H MRS of the musculoskeletal tumors, reviews the literature, discusses current

Glomangioma at the Cervical Spine as an Extradural Dumbbell-Shaped Tumor- a Case Report

A case of glomangioma located at an unusual site, the extradural space of the cervical spine, is presented. To our knowledge, this is the first case that has been identified at this location. Radiographic features of computed tomography (CT) and magnetic resonance (MR) image were collected as a dumbbell-shaped tumor at epidural space of the cervical spine. These features correspond with the histological findings.