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Biomedical subjects

Mark W Wilson

Publications and source records attributed to Mark W Wilson.

At least 19 recordsLinked to original sources
PubMed2006

Sharp recanalization of a short esophageal occluding stricture in a patient with epidermolysis bullosa.

BACKGROUND: Although esophageal strictures caused by epidermolysis bullosa are often treated with balloon dilations, complete obstruction has few effective therapies except esophagectomy with colonic replacement. OBJECTIVE: Resolution of esophageal obstructive lesion without surgical intervention. DESIGN: Case study. SETTING: Interventional radiology. PATIENT: Epidermolysis bullosa with esophageal stricture. INTERVENTION: Endoscopic- and guidewire-guided sharp recanalization. MAIN OUTCOME MEASUREMENT: Radiologic evidence of stricture resolution. RESULTS: Successful recanalization. LIMITATIONS: Experience of operators (anesthesiologist, endoscopist, interventional radiologist). CONCLUSIONS: Sharp recanalization of a complete stricture in patients with epidermolysis bullosa is feasible in a controlled setting.

Adult↗
PubMed2006

Outcomes of tracheobronchial stent placement for benign disease.

PURPOSE: To retrospectively determine long-term outcomes in patients who have undergone tracheobronchial stent placement for benign diseases. MATERIALS AND METHODS: Institutional Review Board approval was obtained for this retrospective HIPAA-compliant study, with waiver of informed consent. Forty patients (22 female, 18 male; mean age, 52.0 years) who were treated with metallic airway stents for benign stenosis were identified from an interventional radiology database. Causes of airway stenosis included transplant stricture (n = 13), tracheal tube injury (n = 10), inflammation (n = 6), tracheobronchomalacia (n = 4), infection (n = 3), and extrinsic compression (n = 4). Follow-up, which ranged from 6 to 2473 days, was performed by means of chart review for deceased patients and by means of clinical visit or telephone interview for surviving patients. Survival, primary patency, and assisted patency were estimated by using the Kaplan-Meier product limits method. RESULTS: Initial technical success was achieved in all cases. Symptomatic improvement was present in 39 of 40 cases. At review, 15 patients were alive and had clinical improvement, 18 had died of comorbid causes, one had died of uncertain causes, three had undergone subsequent airway surgery, two had undergone airway stent retrieval, and one was lost to follow-up. Survival at 1, 2, 3, 4, 5, and 6 years was 79%, 76%, 51%, 47%, 38%, and 23%, respectively. Loss of primary patency was most rapid during the 1st year. With repeat intervention, assisted patency was 90% at 6.8 years. CONCLUSION: Attrition of tracheobronchial stent patency is most rapid during the 1st year, and a high rate of long-term patency can be achieved with secondary interventions. Metallic airway stents are well-tolerated and useful adjuncts for management of select benign tracheobronchial stenoses.

Adult↗
PubMed2006

Orthopedic spinal and hip prostheses: effects of magnetic susceptibility artifacts during MR arteriography and venography of abdomen and pelvis.

PURPOSE: To retrospectively determine if susceptibility artifacts from internal metallic spinal fixation devices and hip prostheses limit the depiction of vascular anatomy and pathologic abnormalities during magnetic resonance (MR) arteriography and venography. MATERIALS AND METHODS: This study was approved by the Committee on Human Research of the Institutional Review Board, which waived the requirement for informed consent and deemed the study to be HIPAA compliant. Forty-two contrast material-enhanced MR angiographic examinations were performed by using a 1.5-T imager in 41 patients (16 men, 25 women; mean age, 57 years; range, 36-79 years); 33 of these examinations included both MR arteriographic and MR venographic components. On the basis of resolution, images for which more than 3 mm of vessels were affected by susceptibility artifacts were considered uninterpretable. The odds of obtaining an uninterpretable image due to metallic artifacts were calculated, and a chi(2) analysis was employed to determine significance. RESULTS: Total hip prostheses and spinal hardware that terminated above the L5 level did not generate any appreciable artifacts at MR arteriography (P < .001) or MR venography (P = .002). In patients with hardware that extended to the sacrum, 88% of MR arteriograms were of diagnostic quality (P = .001), but only 21% of MR venograms were interpretable (P = .004). Artifacts limited the evaluation of the inferior vena cava and common iliac veins near the confluence. CONCLUSION: Diagnostic-quality MR arteriograms and MR venograms can be obtained in patients with artificial hip prostheses and spinal hardware terminating above the L5 level, but there is 79% likelihood of obtaining a nondiagnostic MR venogram in patients with internal spinal fixation devices that extend to the sacrum.

Adult↗
PubMed2006

Tesio catheter access for long-term maintenance hemodialysis.

PURPOSE: To retrospectively determine the long-term outcome (>6 months) of placement of tunneled hemodialysis catheters. MATERIALS AND METHODS: The HIPAA-compliant study protocol was approved by the Committee on Human Research, which waived the requirement for informed consent. The records of patients who underwent hemodialysis with the Tesio system (Medcomp, Harleysville, Pa) at a single outpatient dialysis unit between March 1994 and March 2004 were reviewed. The length of catheter access and the requirements for percutaneous revision were recorded, and unassisted- and assisted-access survival times were computed by using the Kaplan-Meier method. RESULTS: Three hundred three primary Tesio accesses were created in 200 patients (mean age, 62.3 years +/- 16.3 [standard deviation]; 102 women [51.0%]). Fifty-nine of 303 accesses (19.5%) were percutaneously revised with catheter exchange. During follow-up, 200 of 303 accesses (66.0%) were terminated (117 because they were no longer needed and 83 because of catheter malfunction), and 103 (34.0%) accesses were functioning at the time of last follow-up. The mean duration of catheter access was 247 days (range, 3-2016 days). One hundred twenty-six (41.6%) accesses remained in use for more than 6 months; 50 (16.5%), for more than 1 year; 20 (6.6%), for more than 2 years; 14 (4.6%), for more than 3 years; and five (1.7%), for more than 4 years. Assisted-access survival was 78.1%, 60.0%, 51.5%, 51.5%, and 46.8% at 6 months and 1, 2, 3, and 4 years, respectively. CONCLUSION: Tesio catheters frequently function for periods longer than 6 months and, when necessary, they can function for many years.

Adult↗
PubMed2006

Jellyfish aggregations and leatherback turtle foraging patterns in a temperate coastal environment.

Leatherback turtles (Dermochelys coriacea) are obligate predators of gelatinous zooplankton. However, the spatial relationship between predator and prey remains poorly understood beyond sporadic and localized reports. To examine how jellyfish (Phylum Cnidaria: Orders Semaeostomeae and Rhizostomeae) might drive the broad-scale distribution of this wide ranging species, we employed aerial surveys to map jellyfish throughout a temperate coastal shelf area bordering the northeast Atlantic. Previously unknown, consistent aggregations of Rhizostoma octopus extending over tens of square kilometers were identified in distinct coastal "hotspots" during consecutive years (2003-2005). Examination of retrospective sightings data (>50 yr) suggested that 22.5% of leatherback distribution could be explained by these hotspots, with the inference that these coastal features may be sufficiently consistent in space and time to drive long-term foraging associations.

Animals↗
PubMed2005

Management of patients with "ex vacuo" pneumothorax after thoracentesis.

RATIONALE AND OBJECTIVES: To determine clinical outcome in patients who developed "ex vacuo" pneumothorax following thoracentesis and to assess the benefit of chest tube placement for this complication. MATERIALS AND METHODS: We retrospectively reviewed records of 282 patients who underwent 437 thoracenteses at a single institution during a 6-year period. We identified 34 patients (12.1%) who developed a pneumothorax following 39 thoracenteses (8.8%) and then identified a subset of patients with pneumothorax "ex vacuo" defined as a moderate to large hydropneumothorax or small pneumothorax persisting for more than 3 days. Patient charts were reviewed to document the treatment strategy employed and subsequent clinical outcome, which included length of hospital stay, resolution of pneumothorax, reaccumulation of pleural effusion, and overall survival. RESULTS: Ten patients developed "ex vacuo" pneumothroax following thoracentesis. None complained of significant worsening of symptoms following thoracentesis. Seven patients were treated by observation alone and 3 patients underwent tube thorocostomy. A decrease in size of the pneumothorax was observed in only 3 patients, none of whom had a chest tube placed. Effusion completely reaccumulated in 7 patients. All 10 patients died during the follow-up period; the mean survival was 157 days (range: 13-402 days). Survival among patients treated by observation was 191.4 days versus 71.7 days for patients receiving chest tubes. CONCLUSION: Life expectancy for most patients who develop "ex vacuo" pneumothorax following therapeutic thoracentesis is short (<6 months). Chest tube placement is not necessary in asymptomatic patients and is unlikely to provide clinical benefit.

Adult↗
PubMed2005

Percutaneous salvage of a failing rex shunt.

Creation of a mesenterico-left portal vein (PV) shunt with use of autologous internal jugular vein (ie, Rex shunt) is a surgical option for the treatment of symptomatic extrahepatic PV occlusion. Herein a patient is described who underwent angioplasty and stent placement across a shunt stenosis by ultrasound (US)--guided percutaneous transhepatic portal access. Follow-up US has demonstrated continued shunt patency.

Child↗
PubMed2004

Postoperative evaluation of complex aortovisceral and aortorenal reconstructions by magnetic resonance angiography.

RATIONALE AND OBJECTIVES: To assess the ability of magnetic resonance angiography (MRA) to evaluate complex vascular bypass reconstructions of the abdominal aorta and its major branches in the postoperative period. MATERIALS AND METHODS: Thirteen patients with bypass grafts connecting the aorta to visceral, renal, and lower limb inflow vessels were evaluated with MRA. Three of these patients were also studied with digital subtraction angiography soon after MRA was completed. MRA was evaluated for its ability to detect the grafts and to determine the degree of stenosis in the graft conduit or at the anastomoses to native vessels. RESULTS: Detection of graft conduits and anastomotic sites by MRA was 100% and 99%, respectively. Comparison with digital subtraction angiography in a subset of the patients showed a 100% agreement between the two modalities in their description of stenotic disease in graft conduits and 95% agreement in stenosis characterization at graft anastomotic sites. CONCLUSION: MRA of complex aortic reconstructions with bypass grafts to its major abdominal branches arteries accurately describes the resulting complicated vascular anatomy and likely has a high degree of correlation to digital subtraction angiography in describing the disease within the bypass grafts.

Anastomosis, Surgical↗
PubMed2004

Combination treatment of venous thoracic outlet syndrome: open surgical decompression and intraoperative angioplasty.

OBJECTIVE: Residual subclavian vein stenosis after thoracic outlet decompression in patients with venous thoracic outlet syndrome is often treated with postoperative percutaneous angioplasty (PTA). However, interval recurrent thrombosis before postoperative angioplasty is performed can be a vexing problem. Therefore we initiated a prospective trial at 2 referral institutions to evaluate the safety and efficacy of combined thoracic outlet decompression with intraoperative PTA performed in 1 stage. METHODS: Over 3 years 25 consecutive patients (16 women, 9 men; median age, 30 years) underwent treatment for venous thoracic outlet syndrome with a standard protocol at 2 institutions. Twenty-one patients (84%) underwent preoperative thrombolysis to treat axillosubclavian vein thrombosis. First-rib resection was performed through combined supraclavicular and infraclavicular incisions. Intraoperative venography and subclavian vein PTA were performed through a percutaneous basilic vein approach. Postoperative anticoagulation therapy was not used routinely. Venous duplex ultrasound scanning was performed postoperatively and at 1, 6, and 12 months. RESULTS: Intraoperative venography enabled identification of residual subclavian vein stenosis in 16 patients (64%), and all underwent intraoperative PTA with 100% technical success. Postoperative duplex scans documented subclavian vein patency in 23 patients (92%). Complications included subclavian vein recurrent thrombosis in 2 patients (8%), and both underwent percutaneous mechanical thrombectomy, with restoration of patency in 1 patient. One-year primary and secondary patency rates were 92% and 96%, respectively, at life-table analysis. CONCLUSIONS: Residual subclavian vein stenosis after operative thoracic outlet decompression is common in patients with venous thoracic outlet syndrome. Combination treatment with surgical thoracic outlet decompression and intraoperative PTA is a safe and effective means for identifying and treating residual subclavian vein stenosis. Moreover, intraoperative PTA may reduce the incidence of postoperative recurrent thrombosis and eliminate the need for venous stent placement or open venous repair.

Adult↗
PubMed2004

Inferior vena cava thrombosis after transjugular intrahepatic portosystemic shunt revision with a covered stent.

A 42-year-old woman who had undergone multiple revisions of a bare-stent transjugular intrahepatic portosystemic shunt was treated for in-stent stenosis by insertion of a polytetrafluoroethylene (PTFE)-covered stent. Immediately after revision with the covered stent, she developed inferior vena cava (IVC) thrombosis. The potential causes and implications of this complication are discussed.

Adult↗
PubMed2004

Hepatocellular carcinoma: regional therapy with a magnetic targeted carrier bound to doxorubicin in a dual MR imaging/ conventional angiography suite--initial experience with four patients.

Four patients with inoperable hepatocellular carcinoma were treated with a magnetic targeted carrier bound to doxorubicin (MTC-DOX) by using a joint magnetic resonance (MR) imaging/conventional angiography system consisting of a 1.5-T short-bore magnet connected to a C-arm angiography unit by a sliding tabletop. Selective transcatheter delivery of the MTC-DOX to the hepatic artery was monitored by using intraprocedural MR imaging, and interim catheter manipulation was performed with fluoroscopic guidance to optimize agent delivery to the tumor and minimize delivery to normal tissue. The final fraction of treated tumor volume ranged from 0.64 to 0.91. The fraction of affected normal liver volume ranged from 0.07 to 0.30. The dual MR imaging/conventional angiography system shows promise for directing magnetically targeted tumor therapies.

Adult↗
PubMed2003

Azygos arch valves: prevalence and appearance at contrast-enhanced CT.

PURPOSE: To evaluate the prevalence and appearance of azygos arch valves at intravenous contrast material-enhanced computed tomography (CT). MATERIALS AND METHODS: Findings of 309 intravenous contrast-enhanced spiral CT examinations of the chest were retrospectively reviewed. The presence of contrast material reflux into the azygos arch and of a focal bulge in the azygos arch was recorded. An azygos valve was considered present if contrast material with a curvilinear posterior contour was seen in the azygos arch. The chi2 test was used to compare the frequency of contrast material reflux into the azygos vein for high and low rates of contrast material injection and for right and left arm injection. RESULTS: Reflux of contrast material into the azygos arch occurred at 154 (49.8%) of 309 examinations, and valves were seen on images of 105 (68.2%) examinations. A focal bulge was seen in the azygos arch on images of 86 (81.9%) of 105 examinations with an azygos valve. Contrast material refluxed more frequently into the azygos vein in examinations with high rates of injection (83 of 128 examinations, 64.8%) than in those with low rates of injection (71 of 181, 39.2%, P <.001). Among the patients with high rates of injection, contrast material refluxed more frequently into the azygos vein with the right arm injection than with left arm injection (53 of 70, 76% vs 30 of 58, 52%, P <.01). Refluxed contrast material appeared as discrete collections within cusps of the azygos valves on images of 69 (44.8%) of 154 examinations. CONCLUSION: Valves in the azygos arch are common and more frequently seen at CT when high injection rates and right arm injections are used.

Adolescent↗
PubMed2003

Reversal of flow in the ovarian artery during uterine artery embolization.

Uterine artery embolization (UAE) is gaining increasing recognition as an effective treatment alternative to hysterectomy in select patients. As interventional radiologists gain more experience in the treatment of fibroids, new interest is being directed toward arterial communications between the uterine arteries and ovarian arteries. This case report focuses on the potentially serious complication of flow reversal up the ovarian artery into the aorta during UAE.

Adult↗
PubMed2003

Experimental renal artery embolization in a combined MR imaging/angiographic unit.

PURPOSE: The purpose of this study was to use a combined x-ray angiography and MR imaging (XMR) system to manipulate intraarterial catheters and monitor the deposition of gadolinium (Gd)-impregnated embolic microspheres in vivo in a canine kidney model. MATERIALS AND METHODS: Seven anesthetized dogs (18-28 kg) were studied. The renal arteries were catheterized under fluoroscopic guidance. Renal blood flow rates were assessed with velocity-encoded cine MR imaging before and after renal artery embolization with Gd-impregnated microspheres (300-500 and 500-700 micro m in size). The particles were injected in vivo into 14 canine renal arteries under fast dynamic T1-weighted MR imaging guidance at one frame per second. Postembolic microsphere distributions were assessed with MR imaging and digital subtraction angiography (DSA). RESULTS: Gd-impregnated microsphere injection into the renal arteries was successful in all animals. Renal enhancement due to the deposition of the particles persisted for at least 1 hour after the injection. The distribution of MR signal enhancement in the kidneys differed for the smaller versus the larger microspheres. The 300-500- micro m microspheres deposited preferentially in the outer cortical regions, whereas the 500-700- micro m microspheres preferentially deposited in the medulla and inner cortex. Renal blood flow was significantly reduced after the administration of both the 300-500- micro m microspheres (from 3.9 to 1.0 mL/min/g) and the 500-700- micro m microspheres (from 3.5 to 0.2 mL/min/g). CONCLUSION: MR imaging permits real-time guidance of arterial embolization with Gd-impregnated microspheres.

Angiography↗
PubMed2003

Coil embolization of a tuboovarian anastomosis before uterine artery embolization to prevent nontarget particle embolization of the ovary.

Uterine artery embolization (UAE) is being used more frequently as a primary treatment for uterine leiomyoma. Performing UAE in women who desire future fertility is controversial because of the risks of premature menopause and the undetermined effects on pregnancy. The etiology of ovarian failure after UAE is not yet clearly defined, but one of the leading possibilities is nontarget embolization of the ovaries. In this case report, the authors describe a technique of selective coil embolization of a uterine artery-to-ovarian artery communication before UAE performed specifically to protect the ovary from nontarget embolization.

Adult↗