Dynamic Prediction of Advanced Colorectal Neoplasia in Inflammatory Bowel Disease.

BACKGROUND & AIMS: Colonoscopic surveillance is recommended in patients with colonic inflammatory bowel disease (IBD) given their increased risk of colorectal cancer (CRC). We aimed to develop and validate a dynamic prediction model for the occurrence of advanced colorectal neoplasia (aCRN, including high-grade dysplasia and CRC) in IBD. METHODS: We pooled data from 6 existing cohort studies from Canada, The Netherlands, the United Kingdom, and the United States. Patients with IBD and an indication for CRC surveillance were included if they underwent at least 1 follow-up procedure. Exclusion criteria included prior aCRN, prior colectomy, or an unclear indication for surveillance. Predictor variables were selected based on the literature. A dynamic prediction model was developed using a landmarking approach based on Cox proportional hazard modeling. Model performance was assessed with Harrell's concordance-statistic (discrimination) and by calibration curves. Generalizability across surveillance cohorts was evaluated by internal-external cross-validation. RESULTS: The surveillance cohorts comprised 3731 patients, enrolled and followed-up in the time period from 1973 to 2021, with a median follow-up period of 5.7 years (26,336 patient-years of follow-up evaluation); 146 individuals were diagnosed with aCRN. The model contained 8 predictors, with a cross-validation median concordance statistic of 0.74 and 0.75 for a 5- and 10-year prediction window, respectively. Calibration plots showed good calibration. Internal-external cross-validation results showed medium discrimination and reasonable to good calibration. CONCLUSIONS: The new prediction model showed good discrimination and calibration, however, generalizability results varied. Future research should focus on formal external validation and relate predicted aCRN risks to surveillance intervals before clinical application.

Comparision of Lumbar Lordosis According to Different Operative Positions / 대한척추외과학회지

STUDY DESIGN: A study was designed to compare lumbar lordosis in different positions. OBJECTIVES: The aim of this study was to document the changes of segmental and total lumbar lordosis in common operative positions of lumbar spine. SUMMARY OF LITERATURE REVIEW: It is very important to maintain physiologic lumbar lordosis in instrumentation of lumbar spine. MATERIALS AND METHODS: Twenty-six asymptomatic volunteers underwent a series of four lateral lumbar radiographs ; standing, prone on chest roll and prone on Wilson spine table with hip flexion of 60 and 20 degree. Lumbar lordosis and segmental lordotic angle were compared and analyzed regarding to positions. Lordosis in stading position was assumed to be physiologic. RESULTS: In chest roll position, physiologic lordosis was preserved, but segmental lordotic angles of L3-L4 and L4-L5 significantly decreased compared with those in standing position. Total lumbar lordosis in the Wilson table with hip flexion of 60 degree and 20 degree was decreased 42% and 22%, respectively. In Wilson table, segmental lordotic angles of L1-L2, L2-L3, L3-L4 and L4-L5 were significantly decreased compared with those in standing position. CONCLUSIONS: Physiologic lordosis was preserved only under chest roll. Segmental lordotic angles of L5-S1 was not influenced by positions.

Measurement of Blood Flow in the Carotid Arteries Using Color Doppler in Healthy Korean Adults

PURPOSE: To evaluate the blood flow patterns and the velocities of the carotid arteries in healthy Korean adults. MATERIALS AND METHODS: We evaluated the blood flow patterns and measured the peak systolic and end-diastolic velocities of the common, internal and external carotid arteries in 48 healthy adults who did not have cardiovascular disorders and neck lesions. The velocity difference was analyzed according to different age groups. In addition, peak systolic and end-diastolic velocity ratio of the internal to common carotid artery was estimated, and our data were compared with values reported by other authors. RESULTS: Generally, the velocity in the younger age group tends be to higher than in older group. The peak systolic and end diastolic velocities of the internal carotid artery were 84.5cm/sec and 30.5cm/sec. The peak systolic and end diastolic velocity ratio of the internal to common carotid artery were 0.715 and 0.966. The internal carotid artery was less resistant in blood flow than the external carotid artery. Our data were lower than the values which were reported by Bluth et al. CONCLUSION: The blood flow velocities of the internal carotid artery in healthy adults were lower than those of previously reported foreign values, but the patterns were similar.

CT Findings of Abdominal Tuberculosis

PURPOSE: To evaluate the CT features of abdominal tuberculosis by the pattern anaylsis. MATERIALS AND METHODS: We retrosepctively reviewed the CT findings of confirmed abdominal tuberculosis in 16 patients. Of the 16 patients, 1 was man and the remaining 15 were women with an average age of 34.1 years and the highest incidence in the twenties of age. Intravenous and oral contrast agents were used in all patients. The amount and location of ascites and the changes in the omenturn, mesentery, bowel wall, and peritoneum were analyzed. The morphologic feature, size and main compartment of involvement were also evaluated in the cases with lymphadenopathy as well as other changes in intraabdominal organs. RESULTS: The abdominal tuberculosis was more common in the female(15/16, 93.8%) and could be classified into 3 patterns on their CT findings;Complex ascitic, lymphadenopathy, or abscess forms. The complex ascitic form(10/16, 62.5%) was most commonly seen and characterized by uneven distribution and Ioculation of intraperitoneal fluid collection and marked changes of the omenturn and mesentery. The lymphadenopathy form(3/16, 18.8%) was characterized by central low density and peripheral rim enhancement on postcontrast CT with common involvements of porta hepatis and upper abdominal and paraaortic lymph nodes. The abscess form(3/16, 18.8%) was mainly related to the pelvic abscesses. CONCLUSION: CT was valuable in analyzing the patterns of the lesions and making a diagnosis of abdominal tuberculosis.

Hepatic Masses: Differential Diagnosis with Two Phases Imaging by Using Spiral CT

PURPOSE: We compared the contrast enhancement patterns of hepatocellular carcinomas(HCC), hemangiomas, and metastasis on two phase imagings to determine the value of two phase dynamic CT in the differential diagnosis. MATERIALS AND METHODS: Two phases spiral volumetric CT scan were obtained 45 seconds and 6 minutes after bolus injection of contrast material in 106 patients. A bolus of 100 mL of nonionic contrast material was administered intravenously at a injection rate of 2 mL/sec. RESULT:In Hepatocollular carcinoma, 47% were totally hyperdense and 30% were totally hypodense in early phase, and 82% were totally hypodense in late phase. In hemangioma, 90% were peripherally hyperdense in early phase, 52% were isodense and 27% were totally hyperdense in late phase. In metastatic liver malignancies, 65% were hypodense and 32% were peripherally hyperdense in early phase, and 79% were hypodense in late phase. CONCLUSION: Two phases spiral volumetric CT scaning is considered to be heplful in the differential diagnosis of hepatic tumors.

Experimental Microangiographic Study in Normal Rabbit Liver

PURPOSE: Microangiography is an experimental radiologic technique for evaluation of the morphology and the function of small vessels. The purpose of this study is to introduce a good microangiographic technique and to present the microangiographic appearance of normal hepatic vascular pattern. MATERIALS AND METHODS: Five white rabbits weighing 2.5-2.9Kg were objected. Polyethylene catheters were inserted in portal vein and then in IVC. Heparin mixed normal saline (2cc/1000cc) was infused through portal vein and blood was drained to IVC. Barium suspension was infused via the catheter placed in portal vein untill the liver surface showed satisfactory finding in barium filling. The liver was removed and this preparation was fixed in 10% formaline for 7 days. After fixation, the liver was sectioned on 1-2mm thickeness. The slices were radiographed on high resolution plate using Faxitron. H-E staining of liver tissue was also done. RESULTS: The microbrium was well distributed in all small vessels without filling defect. And we could find the hexagonal shaped classic liver Iobule, in which the central vein was located at central portion and portal vein at periphery. The enlargement was showed numerous sinusoids, but there was less dye in the central portion of Iobule, but the central vein was well filled by microbarium. The peripheral portion of Iobule was well filled with microbarium. So, we could find diamond shaped liver acinus, in which central vein was located at priperal portion and the center of liver acinus was terminal portal vein that growed out from a small portal space. The three acini made the complex acinus and acinar agglomerate was composed of three or four complex acini. CONCLUSION: It is considered that the liver acinus pattern of Rapparport is more acceptable on microangiography than the classic concept of hepatic Iobule.

Injection Method of Contrast Medium in Chest Spiral CT

PURPOSE: Authors studied the injection method of contrast medium in routine chest spiral CT scan to obtain the best image in the mediastinum. MATERIALS AND METHODS: Dynamic static scan had been performed in 5 normal volunteers as a pilot study. In consideration of the result of pilot study, Chest spiral CT was performed in 217 patients by three different methods. We used 100cc nonionic contrast medium. Average attenuation of great vessels in the mediastinum were assessed in various injection methods. Image quality was graded with three levels of score by two radiologists. RESULTS: Peak enhancement time of the great vessels on pilot at dynamic static scan were as follows :52 sec at ascending aorta, 45 sec at pulmonary artery, and 40 sec at SVC. In the study of spiral CT, the highest attenMarion in the great vessels was obtained after injection of 100cc of contrast medium(2cc/sec, with 35-40 second scan delay), althrough artifact from highly enhancing SVC was most common in this method. Image quality were highest in the scans obtained with other methods(3-2-1cc/sec for 10-15-40 seconds, with 40 second scan delay). CONCLUSION: For chest spiral CT, authors recommend that scans should be obtained after infusion of 70--80cc of contrast medium during 35--40sec to obtain maximal vascular enhacement of mediastinum.

Measurment of Functioning Hepatocyte Mass using Cardiac Blood Pool Clearance Rates of 99mTc-DISIDA

PURPOSE: The authors investigated the ability of cardiac blood pool clearance rates(CBCR) of 99mTc-DiSiDA in the measure merit of functioning hepatocyte mass. MATERIALS AND METHODS: We measured the volume of Iobectomized liver after completion of postoperative scanning with CBCR of 99rnTc-DISIDA in 5 rabbits who the functional hepatic Iobectomy performed by ligation of hepatic artery, portal vein and biliary tracts. Regarding the measurement of CBCR of 99mTc-DISIDA, we set the time which was decreased to the half of the clearance amount of the cardiac radioactivity by hepatic extraction of 99mTc-DISIDA at the point of 50 sec after the renal peak of the radioactivity to prevent confusing with the blood dilution of the radioactivity, that have called DI-K50. RESULTS: The results were followed that the volumes of the functional hepatic Iobectomy in 5 rabbits were 25%, 25%, 41%, 52%, 75% and the residual functioning hepatocyte masses measured by CBCR of 99rnTc-DISIDA were preserved to 75. 1%, 70. 8%, 63. 0%, 52. 2%, 30. 8% respectively. CONCLUSION: we made decision that CBCR of 99rnTc-DISlDA was useful to evaluate the functioning hepatocyte mass.

Dynamic Study of the Larynx with Spiral CT

PURPOSE: It is essential to know the functional and morphologic changes of the larynx in the evaluation of laryngeal lesions. Conventional CT which has relatively long examination time is not suitable for this aim. The purposes of this study are to evaluate the capability of spiral CT in the dynamic study of the larynx and to know whether this new technique can replace conventional laryngography or not. MATERIALS AND METHODS: Five healthy volunteers and 20 patients with laryngeal lesions underwent spiral dynamic CT scans with 3-dimensional reconstruction of the mucosal surface. A series of spiral CT scans were done while the volunteers performed various laryngeal positions to obtain the functional and morphologic information. The maneuvers used were:quite breathing, "E" phonation, Valsalva maneuver, modified Valsalva maneuver, and a new method of our own, "modified breath holding" technique. The patients were scanned when in quite breathing. Additioal scans were obtained by using the "modified breath holding" technique. RESULTS: The dynamic study with spiral CT could provide high resolutional images which nicely depicted the mobility of vocal cords and the mucosal changes of the laryngeal cavity in both healthy volunteer and patient groups. In patient group, the new "modified breath holding" technique was easier and more reproducible than other maneuvers. CONCLUSION: Spiral CT allows a dynamic study of the larynx and can be a new alternative of laryngography.

Dynamic Liver Scan with Sprial CT

PURPOSE: Dynamic liver scan with spiral CT during a single breath hold was performed for To determing the optimal timing of scanning and the degree of the enhancement of liver and vessel. MATERIALS AND METHODS: Liver spiral CT was performed on 143 patients and dynamic sequence scan on 2 normal volunteers. After baseline spiral CT without contrast enhancement, spiral CT was performed after administration of a bolus of 100 ml of nonionic contrast material intravenously with mechanical power injector at the constant injection rate of 2 ml/sec. Cephalocaudal scanning was started 45 seconds after the beginning of injection. In the majority of cases we employed 16-24 continuous scanning with table feed of 10 mm, slice thickness of 10 mm, and reconstructed in 5 or 10 mm section increments. We measured degree of enhancement of aorta, IVC, and liver parenchyma in all images. RESULTS: We have achieved bolus phase at all images from the following measured date; 170-250 H. U at aorta, 110-150 H. U at IVC, 80-125 H. U at liver parenchyma, 100-130 H. U at spleen, which shown contrast difference between aorta and IVC at least 45 H. U. At the dynamic sequence scan, aortic and vascular CT atternuation reaches a peak at 55-60sec and peak hepatic enhancement occurred at 70-75 sec with relative plateau achieve at 45 sec. Spiral CT also showed elimination of variation in diaphragmatic excursion. CONCLUSION: We could get the disirable phase imaging at overall examination from the dynamic liver scan around 45-60 seconds after injection of contrast media.

MR imaging of intracranial tuberculosis: Emphasis on development of lesions and therapeutic effect

We retrospecively analyzed MRI findings of 14 patients with intracranial tuberculosis according to the disease process before anti-tuberculous medication. We also analyzed the correlativity between these findings and the clinical outcome after anti-tuberculous medication in 8 patients who had taken follow-up MR imaging. MR imaging was performed with either a 0.5T(1 patients) or 1.0T(13 patients) superconducting system with spinecho pulse sequences. Abnormalities on MRI were seen in 87%(12/14) of the patients. MRI findings consisted of meningeal enhancement(n=10), parenchymal tuberculoma(n=6), hydrocephalus(n=5), and infarction(n=5). Most of them were found within 3 months from symptom-onset. Parenchymal tuberculomas were found after 1 month of symptom-onset. All cases of hydrocephalus and infarction were associated with meningeal enhancement. On follow-up MRI after anti-tuberculous medication, changes of MR imaging did not correlate with clinical outocome in 4(50%) of 8 patients. Improvement of MRI findings were observed in patient treated for more than 3 weeks. In conclusion, MRI is a good modality in the diagnosis of intracranial tuberculosis, however, the MRI findings are not always correlated with clinical outcome after, anti-tuberculous medication.