Biomedical subjects
Publications and source records attributed to K M Horton.
This article describes the CT findings in two patients with adenocarcinoma of the colon and gastrocolic fistula which simulated the classic appearance of gastric leiomyosarcoma on CT. The role of CT in the diagnosis of gastrocolic fistula is also discussed.
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PURPOSE: Surgical placement of intraperitoneal catheters for intraperitoneal chemotherapy is associated with bowel perforation, peritonitis, and catheter occlusion. The authors evaluated the safety and efficacy of fluoroscopically guided placement of temporary intraperitoneal catheters for chemotherapy. PATIENTS AND METHODS: Two hundred one intraperitoneal catheter placements were attempted in 88 patients with peritoneal carcinomatosis or sarcomatosis. The peritoneum was punctured with 22-gauge needles and exchange was made with use of Seldinger technique and liberal injections of contrast material at each step for 8.3- or 8.5-F multiple-side-hole catheters. Placement sites included all four quadrants and the midline. Computed tomographic (CT) peritoneography was performed prior to chemotherapy. RESULTS: One hundred ninety (94.5%) of 201 attempted catheter insertions were technically successful. Results of CT peritoneography were available in 175 cases and showed free distribution of peritoneal contrast material in 39% (n = 69), partial loculation in 38% (n = 67), and extensive loculation in 22% (n = 39). Catheters remained in place for a median of 5 days (range, 2-6 days). Significant complications occurred in 11 procedures (5.5%). There were seven unintended bowel intubations; all were treated conservatively except one that required surgical repair. One other patient developed necrotizing fasciitis requiring surgical débridement. Three other patients (1.5%) developed mild peritonitis responsive to antibiotics. Technical success, complications, and peritoneal distribution of contrast material did not correlate with the site of catheter placement. CONCLUSION: Percutaneous catheter placement with use of small-gauge needles for initial puncture is safe and efficacious in patients requiring short-term peritoneal access for chemotherapy.
PURPOSE: Balloon angioplasty and directional atherectomy frequently have short-lived results for stenoses associated with hemodialysis. Results are reported for a phase I trial of the pullback atherectomy catheter (PAC) for treatment of hemodialysis access-related stenoses. PATIENTS AND METHODS: Six intragraft and six venous stenoses in nine patients were treated with the PAC. Two lesions were treated with adjunctive balloon angioplasty, and two were treated with adjunctive directional atherectomy. Clinical and angiographic follow-up were obtained for all patients. All specimens were examined histologically. RESULTS: Initial procedural success was achieved in 83% of stenoses (10 of 12). For intragraft stenoses, the 6-month primary patency was 60% (three of five) and the 6-month secondary patency was 80% (four of five). All six venous stenoses restenosed or thrombosed within 3 months. All specimens contained fibrous plaque or intimal hyperplasia. In addition, all six venous stenosis specimens contained media and two contained adventitia. Significant complications during treatment of venous stenoses included severe venous spasm in three and venous pseudoaneurysms in two. One PAC tip fracture occurred during treatment of an intragraft stenosis. CONCLUSION: Pullback atherectomy is potentially safe and effective for intragraft stenoses; however, it is not safe or effective for venous stenoses.
PURPOSE: Areas of anastomotic stenosis in lower-extremity bypass grafts (BPGs) were treated by means of directional atherectomy (DA) in hopes of achieving better patency rates than have been reported with percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: During a 4-year period, 17 patients (11 men and six women) with 23 areas of anastomotic stenosis in 18 lower-extremity BPGs were selected for treatment with DA. Urokinase thrombolysis was initially performed in eight BPGs that were thrombosed at the time of presentation. Adjunctive preatherectomy PTA was performed in six lesions, and postatherectomy PTA was performed in three lesions. RESULTS: The technical success rate for DA was 92% (23 of 25 sites). There was less than 50% restenosis at 74% of the areas of stenosis (14 of 19 sites), with a mean follow-up time for the sites of 13 months. The graft patency rate was 88% (14 of 16 grafts), with a mean follow-up time for the grafts of 14 months. Areas of stenosis treated with DA alone had the same patency rates as those treated with DA and PTA. CONCLUSIONS: DA is an effective treatment method for anastomotic peripheral arterial BPG stenosis. The intermediate-term patency rates following DA are superior to those reported for PTA and similar to those reported for surgical revision.
PURPOSE: To evaluate the performance of the ergonomic vascular access needle (EVAN), which is designed to contain blood while allowing for observation of pulsations before passage of a guide wire, in arterial catheterization. MATERIALS AND METHODS: EVANs were used for initial puncture in 118 arterial access procedures. Visualization of pulsatile blood motion and containment of blood were prospectively evaluated. Results from 82 separate procedures performed with standard access needles were used as a control. Success or failure of guide-wire passage through the needle, number of attempts, guide-wire type, findings on the access vessel arteriogram, and complications were recorded for both groups. RESULTS: In the EVAN group, 92% of procedures were successfully completed, usually within two attempts (82%). Success was independent of guide-wire type (P = .4) and was not significantly different from that of the control group (96%) (P = .37). In 89% of the EVAN procedures, contained pulsatile blood motion was observed before attempted guide-wire passage. Uncontrolled spraying of pulsatile blood did not occur unless the hemostasis valve was removed. In 16%, slow oozing of blood occurred through the needle hub, mainly during guide-wire passage. Oozing was common with floppy-tipped guide wires (46%) but was uncommon with stiffer-tipped wires (6%). There were no needle-related complications. CONCLUSION: The EVAN provides protection from blood spray while allowing for successful guide-wire passage into the arterial system as often as standard access needles. However, slow periwire leakage occurs frequently with floppy-tipped guide wires.
PURPOSE: To report the results of the FDA phase II, multicenter trial of the Wallstent in the iliac and femoral arteries. PATIENTS AND METHODS: Two hundred twenty-five patients entered the trial. Stents were placed in the iliac system in 140 patients and in the femoral system in 90 (five patients required both iliac and femoral stents). Clinical patency was measured over 2 years by means of life-table analysis with use of clinical and hemodynamic data and the Rutherford scale. Angiographic patency was measured at 6 months. RESULTS: In the iliac system the primary clinical patency was 81% at 1 year and was 71% at 2 years. The secondary clinical patency was 91% and 86%, respectively. The 6-month angiographic patency was 93%. In the femoral system the primary clinical patency was 61% at 1 year and 49% at 2 years. The secondary patency was 84% and 72%, respectively. The 6-month angiographic patency was 80%. CONCLUSIONS: The results are similar to those with the Palmaz stent in the iliac system and with angioplasty alone in the iliac and femoral systems.
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PURPOSE: Our purpose was to determine if patients with pseudomembranous colitis (PMC) requiring surgical intervention demonstrate radiographic features distinct from those of patients treated successfully with standard medical therapy. METHOD: The indications for a CT study and the imaging findings from 17 patients who required laparotomy with colon resection for PMC were retrospectively reviewed. The CT findings were compared with the findings from 17 control patients (matched by clinical presentation) with PMC who were treated medically and did not require surgical intervention. RESULTS: None of the CT findings evaluated in this study were significantly different between the surgical and nonsurgical groups. The CT findings evaluated for the surgical and nonsurgical groups, respectively, were as follows: wall thickness of the colon: 17.8+/-6.6 and 16.9+/-3.9 mm; largest caliber of the colon: 6.8+/-1.6 and 6.1+/-1.2 cm; presence of the accordion sign: 52.9 and 70.6%; heterogeneous contrast enhancement pattern (target sign): 57.1 and 57.1%; pericolonic stranding: 82.4 and 88.2%; ascites: 70.6 and 58.8%; pleural effusion(s): 64.7 and 64.7%; and subcutaneous edema: 64.7 and 64.7%. CONCLUSION: Although none of the CT findings evaluated in this study was significantly different between the surgical and nonsurgical groups, CT was often the initial diagnostic modality in both groups. It is important for radiologists to recognize the CT appearance of PMC and suggest the diagnosis. However, patient triage may not be based solely on the CT findings.
This article reviews the CT imaging features of a variety of nonneoplastic conditions that affect the small bowel and stresses important distinctive patterns that may help distinguish specific entities. Various inflammatory conditions (Crohn disease, radiation enteritis, graft versus host disease, celiac disease, Whipple disease, eosinophilic gastroenteritis, Behçet disease) as well as infiltrative disorders (amyloidosis, lymphangiectasia) and infectious diseases (Mycobacterium avium intracellulare, cytomegalovirus, cryptosporidiosis) are reviewed, with key differential points emphasized. In addition, miscellaneous conditions such as ischemia, small bowel diverticulitis, and small bowel hemorrhage are discussed.
PURPOSE: The purpose of this work was to determine normal contrast enhancement of the small bowel with biphasic spiral CT, using water as oral contrast agent. METHOD: Biphasic spiral CT was performed in 50 healthy patients undergoing evaluation as potential renal donors. All patients received 500 ml of water as oral contrast agent and 150 ml of Omnipaque 350 administered by mechanical injector at a rate of 3 ml/s. Dual phase CT of the abdomen was performed in each patient. Acquisition of early phase images began 30 s after the start of the intravenous injection, and portal phase images were obtained 60 s after initiation of the contrast agent injection. Attenuation measurements (in Hounsfield units) were obtained from the wall of the small bowel (duodenum, jejunum, ileum) in both the arterial and the portal phases. RESULTS: During the arterial phase, the mean (95% confidence interval) attenuation of the duodenum, jejunum, and ileum was 120 (+/- 5), 119 (+/- 5), and 118 (+/- 5) HU, respectively. During the portal phase, the average attenuation of the duodenum, jejunum, and ileum was 111 (+/- 4), 111 (+/- 3), and 107 (+/- 3) HU, respectively. There was no statistically significant difference between the attenuation of the duodenum, jejunum, or ileum within either the arterial or the portal venous phases. There was a statistically significant difference in small bowel enhancement between the arterial and portal venous phases. CONCLUSION: There is no important variation in small bowel attenuation during the 30 and 60 s scanning phases. This study serves as a normal reference that may be helpful when spiral CT is used to evaluate ischemic bowel or inflammatory small bowel diseases.
Multidetector CT (MDCT) provides unparalleled capabilities for combining narrow scan collimation with rapid data acquisition protocols. When combined with CT angiographic techniques and 3D-volume rendering we are able to create unique displays for evaluating a range of clinical pathologies. In this pictorial review we present the potential advantages of using MDCT angiography for the evaluation of pancreatic cancer and its role in the accurate staging of these patients. The use of dual-phase CT scanning in both the arterial phase and portal phase is addressed with the role of 3D CT angiography clearly defined. Numerous case studies are presented to show the advantages of these techniques over simple axial CT imaging.
Helical CT evaluation of the abdomen and pelvis can be challenging in the cancer patient. This pictorial essay illustrates the important sites of neoplastic dissemination in the abdomen and pelvis. We will emphasize the classic CT appearance of several selected sites and indicate, where appropriate, the primary lesions usually associated with each.
Benign hepatic and biliary tumors can present a difficult diagnostic challenge. Spiral computed tomography (CT) and magnetic resonance (MR) imaging are useful in the detection and characterization of these tumors. Imaging characteristics of lesions such as hepatic cyst, hemangioma, focal nodular hyperplasia (FNH), and hepatic adenoma are well known. Hepatic cysts demonstrate water attenuation at CT, are isointense relative to water at MR imaging, and do not enhance after intravenous administration of contrast material. Hemangiomas demonstrate characteristic nodular peripheral enhancement on early-phase images with subsequent fill-in centrally at both modalities. FNH classically demonstrates intense early enhancement with washout on delayed images. Although hepatic adenoma can also demonstrate intense early enhancement, it has a tendency to bleed and thus often appears more heterogeneous than FNH due to hemorrhage. Benign hepatic tumors that are less well described in the imaging literature include hepatic lipoma or angiomyolipoma, infantile hemangioendothelioma, and mesenchymal hamartoma. Hepatic lipoma has fat attenuation at CT, is isointense relative to fat at MR imaging, and does not enhance after intravenous administration of contrast material. Hepatic angiomyolipomas contain a variable amount of soft tissue in addition to fat and may therefore demonstrate enhancement at both modalities. The CT and MR imaging appearances of infantile hemangioma are similar to those of adult hemangioma. Infantile hemangioendothelioma occurs in infants under 6 months of age and is typically a larger lesion. Mesenchymal hamartoma also occurs in children, and its imaging appearance depends on the presence of stromal elements and the protein content of the cyst fluid. Familiarity with these imaging features can help distinguish particular disease entities.
Pseudomembranous colitis (PMC) is a potentially life-threatening acute infectious colitis caused by one or more toxins produced by an unopposed proliferation of Clostridium difficile bacteria. PMC is characterized by the presence of elevated, yellow-white plaques forming pseudomembranes on the colonic mucosa. These plaques can be visualized at both pathologic analysis and endoscopy. Plain radiography, contrast enema studies, and computed tomography (CT) are useful in the evaluation of PMC. Plain radiography of the abdomen can demonstrate polypoid mucosal thickening, "thumbprinting" (wide transverse bands associated with haustral fold thickening), or gaseous distention of the colon. A toxic megacolon with distention and occasionally pneumoperitoneum may be seen in the most severe cases of PMC involving perforation. At contrast enema studies, the primary finding in mild cases of PMC is small nodular filling defects representing the mucosal plaques. With more extensive colonic involvement, the plaques are larger and coalesce to form an irregular bowel wall margin. Mural thickening and wide haustral folds caused by intramural edema may also be seen. A contrast enema study is contraindicated in patients with severe PMC due to the danger of perforation. Common CT findings include wall thickening, low-attenuation mural thickening corresponding to mucosal and submucosal edema, the "accordion sign," the "target sign" ("double halo sign"), pericolonic stranding, and ascites. Familiarity with these imaging characteristics may allow early diagnosis and treatment and prevent progression to more serious pathologic conditions.
Colorectal cancer is a common malignancy that results in significant morbidity and mortality. Abdominal computed tomography (CT) is valuable in planning surgery for colon cancer because it can demonstrate regional extension of tumor as well as adenopathy and distant metastases. At CT, colorectal cancer typically appears as a discrete soft-tissue mass that narrows the colonic lumen. Colorectal cancer can also manifest as focal colonic wall thickening and luminal narrowing. Complications of primary colonic malignancies such as obstruction, perforation, and fistula can be readily visualized with CT. At CT, local extension of tumor appears as an extracolic mass or simply as thickening and infiltration of pericolic fat. Extracolic spread is also suggested by loss of fat planes between the colon and adjacent organs. The liver is the predominant organ to be involved with metastases from colorectal cancer. At CT, hepatic metastases usually appear as hypoattenuating masses, which are best visualized during the portal venous phase of liver enhancement. Other common sites of metastases from colon cancer include the lungs, adrenal glands, and bones. Use of CT is critical for identifying recurrences, evaluating anatomic relationships, documenting "normal" postoperative anatomy, and confirming the absence of new lesions during and after therapy.
Computed tomography (CT) is valuable for detection and characterization of many inflammatory conditions of the colon. At CT, a dilated, thickened appendix is suggestive of appendicitis. A 1-4-cm, oval, fatty pericolic lesion with surrounding mesenteric inflammation is diagnostic of epiploic appendagitis. The key to distinguishing diverticulitis from other inflammatory conditions of the colon is the presence of diverticula in the involved segment. In typhlitis, CT demonstrates cecal distention and circumferential thickening of the cecal wall, which may have low attenuation secondary to edema. In radiation colitis, the clinical history is the key to suggesting the diagnosis because the CT findings can be nonspecific. The location of the involved segment and the extent and appearance of wall thickening may help distinguish Crohn disease and ulcerative colitis. In ischemic colitis, CT typically demonstrates circumferential, symmetric wall thickening with fold enlargement. CT findings of graft-versus-host disease include small bowel and colonic wall thickening, which may result in luminal narrowing and separation of bowel loops. In infectious colitis, the site and thickness of colon affected may suggest a specific organism. The amount of wall thickening in pseudomembranous colitis is typically greater than in any other inflammatory disease of the colon except Crohn disease.