PubMed Health⌕ Search

Biomedical subjects

Hoon Ji

Publications and source records attributed to Hoon Ji.

11 recordsLinked to original sources
PubMed2003

CT of acute bowel ischemia.

Bowel ischemia may be caused by many conditions and manifest with typical or atypical and specific or nonspecific clinical, laboratory, and radiologic findings. It may mimic various intestinal diseases and be confused with certain nonischemic conditions clinically and at computed tomography (CT). Bowel ischemia severity ranges from mild (generally transient superficial changes of intestinal mucosa) to more dangerous and potentially life-threatening transmural bowel wall necrosis. Causes of critically reduced blood flow to the bowel are diverse, ranging from occlusions of mesenteric arteries or veins to complicated bowel obstruction and overdistention. CT can demonstrate changes in ischemic bowel segments accurately, is often helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications. Unfortunately, common CT findings in bowel ischemia are not specific, and specific findings are rather uncommon. Therefore, it often is a combination of nonspecific clinical, laboratory, and radiologic findings-especially detailed knowledge about the pathogenesis of acute bowel ischemia in different conditions-that helps most in correct interpretation of CT findings. To improve understanding of this complex heterogeneous entity, this article provides an overview of the anatomy and physiology of mesenteric perfusion and discussions of causes and pathogenesis of acute bowel ischemia, CT findings in various types of acute bowel ischemia, and potential pitfalls of CT.

Acute Disease↗
PubMed2003

Multislice CT colonography: current status and limitations.

CT colonography (CTC) is a promising method for colorectal screening providing a full structural evaluation of the entire colon and gaining in popularity due to a superior safety profile, a low rate of complications, and high patient acceptance. Multislice CT (MSCT) has further improved the diagnostic potential of CTC by generating high-resolution CT images of the abdomen and pelvis in shorter acquisition times than was previously possible. Over the past year, multiple studies have been published on every aspect of CTC including techniques, image display, image reconstruction, and clinical trial results assessing the feasibility of CTC as a screening tool. Yet despite increasing clinical use, the appropriate role of CTC in colorectal cancer screening remains undefined and barriers to widespread adoption remain. In particular, though the test is generally regarded as easy to perform, accurate interpretation requires a steep learning curve. While several large studies have found high sensitivity and specificity, the accuracy of CTC in a screening population has yet to be verified and almost no health insurance plans reimburse for its use in colorectal screening. Ongoing research in computer-aided detection and new software tools, however, have the potential to increase accuracy and ease of interpretation significantly, accelerating its acceptance as a colorectal screening tool.

Colon↗
PubMed2003

Acute small bowel ischemia: CT imaging findings.

Small bowel ischemia is a disorder related to a variety of conditions resulting in interruption or reduction of the blood supply of the small intestine. It may present with various clinical and radiologic manifestations, and ranges pathologically from localized transient ischemia to catastrophic necrosis of the intestinal tract. The primary causes of insufficient blood flow to the small intestine are various and include thromboembolism (50% of cases), nonocclusive causes, bowel obstruction, neoplasms, vasculitis, abdominal inflammatory conditions, trauma, chemotherapy, radiation, and corrosive injury. Computed tomography (CT) can demonstrate changes because of ischemic bowel accurately, may be helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications. However, common CT findings in acute small bowel ischemia are not specific and, therefore, it is often a combination of clinical, laboratory and radiologic signs that may lead to a correct diagnosis. Understanding the pathogenesis of various conditions leading to mesenteric ischemia and being familiar with the spectrum of diagnostic CT signs may help the radiologist recognize ischemic small bowel disease and avoid delayed diagnosis. The aim of this article is to provide a review of the pathogenesis and various causes of acute small bowel ischemia and to demonstrate the contribution of CT in the diagnosis of this complex disease.

Diagnosis, Differential↗
PubMed2002

CT findings in isolated ischemic proctosigmoiditis.

The purpose of our study was to describe the CT features of ischemic proctosigmoiditis in correlation with clinical, laboratory, endoscopic, and histopathologic findings. Our study included seven patients with isolated ischemic proctosigmoiditis. Patients were identified by a retrospective review of all histopathologic records of colonoscopic biopsies performed during a time period of 4 years. All patients presented with left lower abdominal quadrant pain, bloody stools, and leukocytosis, and four patients had fever at the time of presentation. Four of seven patients suffered from diarrhea, one of seven was constipated and two of seven had normal stool consistency. The CT examinations were reviewed by two authors by consensus and compared with clinical and histopathologic results as well as with the initial CT diagnosis. The CT showed a wall thickening confined to the rectum and sigmoid colon in seven of seven patients, stranding of the pararectal fat in four of seven, and stranding of the perisigmoidal fat in one of seven patients. There were no enlarged lymph nodes, but five of seven patients showed coexistent diverticulosis and in three of these patients CT findings were initially misinterpreted as sigmoid diverticulitis. Endoscopies and histopathologic analyses of endoscopic biopsies confirmed non-transmural ischemic proctosigmoiditis in all patients. Isolated ischemic proctosigmoiditis often presents with unspecific CT features and potentially misleading clinical and laboratory findings. In an elderly patient or a patient with known cardiovascular risk factors the diagnosis of ischemic proctosigmoiditis should be considered when wall thickening confined to the rectum and sigmoid colon is seen that is associated with perirectal fat stranding.

Aged↗
PubMed2002

Magnetic resonance imaging. Liver-specific contrast agents.

MR imaging with new liver-specific contrast agents will probably be the imaging modality used in the future to detect focal liver lesions. The detection of HCC will probably be improved by using specific hepatobiliary agents, but the exact technique remains to be determined. New liver-specific contrast can differentiate some benign lesions from malignant ones and can assist in making a final diagnosis. In certain circumstances, liver-specific contrast agents can be used to evaluate hepatic vessels, the biliary tract, and hepatic function. New applications are also expected.

Contrast Media↗
PubMed2002

Computed tomography and magnetic resonance imaging of hepatic metastases.

The detection and characterization of liver metastases is well performed with either computed tomography or magnetic resonance imaging. The administration of intravenous contrast is essential for almost all indications, with multiphasic imaging aiding in lesion characterization and detection. The use of multidetected CT (MDCT) provides the ability for optimized vascular and multiplanar imaging, but has also resulted in increased examination complexity. Tissue-specific MR contrast agents can yield the highest rate of lesion detection and thus may be useful in presurgical planning.

Contrast Media↗
PubMed2001

Portal-venous gas unrelated to mesenteric ischemia.

The aim of this study was to report on 8 patients with all different non-ischemic etiologies for portal-venous gas and to discuss this rare entity and its potentially misleading CT findings in context with a review of the literature. The CT examinations of eight patients who presented with intrahepatic portal-venous gas, unrelated to bowel ischemia or infarction, were reviewed and compared with their medical records with special emphasis on the pathogenesis and clinical impact of portal-venous gas caused by non-ischemic conditions. The etiologies for portal-venous gas included: abdominal trauma ( n=1); large gastric cancer ( n=1); prior gastroscopic biopsy ( n=1); prior hemicolectomy ( n=1); graft-vs-host reaction ( n=1); large paracolic abscess ( n=1); mesenteric recurrence of ovarian cancer superinfected with clostridium septicum ( n=1); and sepsis with Pseudomonas aeruginosa ( n=1). The clinical outcome of all patients was determined by their underlying disease and not negatively influenced by the presence of portal-venous gas. Although the presence of portal-venous gas usually raises the suspicion of bowel ischemia and/or intestinal necrosis, this CT finding may be related to a variety of non-ischemic etiologies and pathogeneses as well. The knowledge about these conditions may help to avoid misinterpretation of CT findings, inappropriate clinical uncertainty and unnecessary surgery in certain cases.

Abdominal Injuries↗
PubMedDate not supplied

Normal colonic wall thickness at CT and its relation to colonic distension.

PURPOSE: The purpose of this work was to analyze the relation between normal colonic wall thickness at CT and local colonic distension. METHOD: One hundred consecutively acquired patients were included in our study. All patients were asymptomatic regarding their intestine, and their history was always negative for intestinal disease. All CT examinations were performed for other reasons than intestinal disease. Colonic wall thickness at CT was measured digitally in every patient at four locations and set in relation to the local colonic distension. RESULTS: The normal colonic wall thickness ranged from 0 to 2 mm in colonic segments with a diameter of >/=4-6 cm, from 0.2 to 2.5 mm in colonic segments with a diameter of 3-4 cm, from 0.3 to 4 mm in colonic segments with a diameter of 2-3 cm, and from 0.5 to 5 mm in colonic segments with a diameter of 1-2 cm. Maximal colonic wall thickness ranged up to 6 and 8 mm in the proximal and distal colon, respectively, if the measured colonic segment showed a luminal width of <1 cm according to contraction. DISCUSSION: The normal colonic wall thickness at CT should be regarded as a dynamic value that stays in clear relation to the local colonic distension. In contracted colonic segments, a colonic wall thickness of 6-8 mm may still be normal. On the other hand, a colonic wall measuring 5 and 3 mm should be regarded as thickened if found in colonic segments with a luminal width of >2 and 4 cm, respectively.

Colon↗
PubMedDate not supplied

Differentiation of chronic focal pancreatitis from pancreatic carcinoma by in vivo proton magnetic resonance spectroscopy.

OBJECTIVE: To determine the differences between the in vivo proton magnetic resonance spectroscopy (H-MRS) features of chronic focal pancreatitis and pancreatic carcinoma and to evaluate the possibility of discriminating chronic focal pancreatitis from pancreatic carcinoma by analysis of in vivo H-MR spectra. METHODS: The H-MR spectra from 36 human pancreases were evaluated in vivo. This series included 15 cases of chronic focal pancreatitis and 21 cases of pancreatic carcinoma. All cases were confirmed histopathologically after surgical resection. The ratios of the peak area (P) of all peaks at 1.6-4.1 ppm to lipid (0.9-1.6 ppm) (P [1.6-4.1 ppm]/P [0.9-1.6 ppm]) in the chronic focal pancreatitis and pancreatic carcinoma groups were evaluated, and the results were compared. The sensitivity and specificity of the analysis were also evaluated by in vivo H-MR spectra for discriminating between chronic focal pancreatitis and pancreatic carcinoma. RESULTS: In vivo H-MR spectra showed significantly less lipid in chronic focal pancreatitis than in pancreatic carcinoma. The ratio of P (1.6-4.1 ppm)/P (0.9-1.6 ppm) in chronic focal pancreatitis was significantly higher than that in pancreatic carcinoma (P < 0.05) because of a decreased peak area of lipids. The means +/- SDs of P (1.6-4.1 ppm)/P (0.9-1.6 ppm) in the chronic focal pancreatitis and pancreatic carcinoma groups were 2.78 +/- 1.67 and 0.51 +/- 0.49, respectively. Using a value of <2.5 as positive for pancreatic cancer, the sensitivity and the specificity for pancreatic cancer were 100% and 53.3%, respectively. CONCLUSION: Chronic focal pancreatitis and pancreatic carcinoma can be distinguished from each other by analysis of in vivo H-MR spectra, and in vivo H-MRS can be a useful method for making a differential diagnosis between chronic focal pancreatitis and pancreatic carcinoma.

Adult↗