Pulmonary embolism during compression US of the lower extremity.
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Biomedical subjects
Publications and source records attributed to J G Letourneau.
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Changes in flow in the subclavian artery and vein resulting from the use of a hyperabduction maneuver during Doppler sonography in 20 volunteers were compared with retrospective findings in 16 patients clinically suspected of having thoracic outlet syndrome. Significant compression of the subclavian artery showed in the Doppler waveform as at least a doubling of peak systolic velocity or complete cessation of flow with hyperabduction; significant compression of the subclavian vein was diagnosed by complete cessation of blood flow or loss of atrial and respiratory dynamics in the waveform of the subclavian vein with hyperabduction. In volunteers, asymptomatic compression of the subclavian vein with arm abduction was seen in two (10%) and asymptomatic compression of the subclavian artery was seen in four (20%). Of the 16 patients, thrombosis of the subclavian vein was found in seven, compression of the subclavian vein with hyperabduction was found in six, and diagnoses other than thoracic outlet syndrome were established as the cause of pain in three. When duplex sonography was compared with venography, which was performed in 10 patients, one false-negative case was found because a subclavian vein thrombus had not been detected. The subclavian artery was examined in five of the six patients with positional compression of the subclavian vein; compression of the subclavian artery was found in three. The clinical significance of compression of the subclavian artery cannot be determined from our data because of the small number of patients involved. When the sonographic criteria of subclavian vein clot or compression resulting in a complete loss of normal venous phasicity with arm abduction and the clinical criterion of subsequent improvement in symptoms after curative surgery are used, color Doppler sonography is 92% sensitive and 95% specific for the diagnosis of thoracic outlet syndrome. This preliminary study shows that Doppler sonography has potential in the evaluation of thoracic outlet syndrome.
The authors describe 10 liver transplant recipients who developed occlusion of the hepatic artery or aortic conduit. Since all potential collateral arterial supply to the transplant is severed at hepatectomy, hepatic artery occlusion is usually a catastrophic event that necessitates repeat transplantation. Four patients died within 8 weeks of transplantation. The remaining six developed spontaneous arterial liver revascularization. This phenomenon is believed to be an example of neovascularization through angiogenesis. Radiologic studies, particularly duplex sonography and angiography, were helpful in the evaluation of transplant vascular integrity. The tissues of the omentum and the mesentery have known angiogenic ability. The authors postulate that in transplantation techniques in which these tissues are placed close to the transplanted liver (eg, Roux-en-Y choledochojejunostomy), the omental and mesenteric tissues may be the source of neovascularity.
A prospective longitudinal study of chest-wall deformity after tissue expansion for breast reconstruction was performed in 19 women. CT imaging was a sensitive method for detecting occult deformity. Using a semiquantitative scale for measuring deformity, all patients and 94 percent of expanders had some thoracic abnormality after tissue expansion. Rib and chest-wall contour changes were observed under 81 and 68 percent of the expanders, respectively. Routine chest roentgenograms were not a sensitive method for evaluating these deformities. The magnitude of deformity after unilateral expansion was not significantly different from that after bilateral expansion. Linear regression analysis indicated that early periprosthetic capsular contracture was negatively correlated with chest wall deformity. Only one patient experienced a clinically noticeable complication from chest compression--transient postexpansion exertional dyspnea. After removing the expanders and placing permanent implants along with capsulotomy, the mean deformity index decreased by 57 percent after 10.5 months median follow-up, which was highly significant (p less than 0.001). Our findings suggest that chest-wall deformity is a common occurrence after tissue expansion in patients undergoing breast reconstruction and is usually of minor clinical significance.
Transplantation of the pancreas is an increasingly common therapeutic option for preventing or delaying complications of type I diabetes mellitus. The authors studied the relative roles of various radiologic examinations in diagnosing vascular complications in these grafts including arterial and venous thrombosis, stenosis, and anastomotic leak (the most common vascular factors that necessitate pancreatectomy of the transplant), as defined with pathologic or arteriographic data. The results of 78 scintigraphic flow studies, 40 abdominal and pelvic computed tomographic (CT) scans, 27 sonograms, and eight color Doppler studies were evaluated in 52 patients who received a total of 27 cadaveric and 26 living-donor grafts over a 12-year period. These results were correlated with the data from 45 gross and microscopic pathologic studies and 37 arteriograms to determine their relative value in enabling detection of graft thrombosis and other vascular complications. Scintigraphy, CT, sonography, and color Doppler were all sensitive in detection of generalized graft abnormalities but lacked specificity in defining the underlying etiologic factors.
The purpose of this study was to evaluate the use of intravascular sonography for the detection of arteriosclerosis and to determine the effects of vascular interventional procedures on the arterial wall. A catheter-based 20-MHz transducer was used. Forty patients were studied. Twelve had clinical evidence of peripheral vascular disease, 13 were healthy renal donors, and 15 underwent vascular interventional procedures. The aorta and the ipsilateral iliac artery were examined in real time under fluoroscopic guidance and the results were compared with angiography. Sonography in eight of the 13 renal donors showed arterial wall abnormalities in the absence of angiographic evidence of disease. Sonography of the 15 patients after angioplasty or atherectomy demonstrated plaque fractures, intramural dissections, or atherectomy grooves. Our experience suggests that intravascular sonography is of value in reducing the use of angiography to monitor progress or complications of vascular interventional procedures.
The preoperative detection of peritoneal metastases from gynecologic malignancies is difficult; in particular, CT often fails to detect peritoneal implants. This study was designed to determine if the administration of intraperitoneal iodinated contrast media would increase the CT detection of such peritoneal metastases. Prospectively, both standard and intraperitoneal contrast-enhanced CT studies of the abdomen and pelvis were performed in 16 patients with suspected gynecologic tumors. All patients then underwent operative staging, with the location and number of metastases documented. The intraperitoneal enhanced CT studies were more sensitive in the detection of peritoneal metastases than standard CT examinations. Whereas routine CT detected peritoneal metastases in seven (64%) of 11 patients with surgically proved implants, the intraperitoneal enhanced CT studies detected peritoneal metastases in all 11 patients. Depending on the specific intraperitoneal compartments involved, the sensitivity of intraperitoneal enhanced CT in the detection of peritoneal metastases was two- to fourfold greater than that of standard CT examinations. Our results suggest that intraperitoneal enhanced CT is superior to standard CT in the detection of peritoneal metastases.
Intravascular US studies were performed with a 20 MHz rotating transducer mounted on a long flexible shaft in 14 patients undergoing interventional vascular procedures--i.e. percutaneous transluminal angioplasty (PTA), atherectomy with a Simpson device, and Palmaz stent placement. Intravascular US was used immediately before the procedure to assess the lesion characteristics and during and after the procedure to verify its results. In PTA, intravascular US clearly shows the fracture of the plaque, its separation from the medial layer, and the total longitudinal extension of the intimal flaps. Palmaz stents are clearly shown and their correct positioning on the arterial wall is therefore precisely evaluated. After atherectomy, intravascular US shows the changes in wall thickness and identifies the areas where more tissue needs to be removed. Intravascular US appears to be a very promising technique for monitoring and directing revascularization procedures by helping select the correct interventional procedure. The initial limitation of use of intravascular ultrasound catheters to straight arterial segments has been resolved by the development of over-the-wire catheters. Further technical development and clinical research are needed.
The computed tomographic (CT) findings in pancreas transplant rejection have been reported to include graft swelling and inhomogeneity. We report a patient with transplant rejection in whom the preoperative CT examination and specimen radiographs revealed large cystic structures within the pancreas. Cystic central necrosis has previously been reported in patients with pancreatitis, but here it is associated with transplant rejection.
Gianturco self-expandable stents were used successfully in the management of 5 patients with tracheobronchial pathology. Placement was performed under endoscopic and fluoroscopic guidance. None of the patients has experienced complications secondary to the stent placement, and in all of them the clinical problems resolved satisfactorily. Longer follow-up is required to determine the place of tracheobronchial stenting in patients with respiratory compromise.
The Simpson atherectomy catheter has been used successfully to recanalise eleven complete occlusions of the iliac and femoropopliteal arteries. Atherectomy and angioplasty were used in combination in 8 cases. Following atherectomy, all patients showed clinical improvement. Distal pulses returned in 7; rest pain and/or claudication disappeared in the other 4. Ischaemic ulcers healed in the 2 affected patients. Overall, ankle-arm indices (AAI) improved by an average of 0.43, with the improvement being greatest (0.55) in patients in whom the lumen was recanalised to within 91-100% of the native luminal diameter. Seven patients have remained with stable AAI values and without change in their clinical status at 18 months follow-up.
A 72-year-old patient underwent uneventful prostatic urethroplasty by means of a balloon catheter. The immediate follow-up retrograde urethrogram failed to demonstrate any areas of extravasation and showed a significant increase in prostatic urethral caliber. Three weeks after the patient was discharged, computed tomography demonstrated a large perineal abscess that was attributed to either the prostatic urethroplasty or subsequent Foley catheter manipulations. The abscess was drained percutaneously, and the patient recovered uneventfully. It was concluded that the abscess was a possible isolated complication and that the procedure is warranted in an adequate clinical setting.
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Duplex Doppler sonography recently has been used to evaluate renal transplants. Some authors have stated that high resistive indexes (RIs) occur in the presence of acute renal transplant rejection. RIs less than 0.7 are considered as probably excluding acute transplant rejection. We performed a prospective study of duplex sonographic examinations of pediatric patients (mean age, 8 years; 13 boys, two girls) with renal allografts and clinically suspected transplant disease. The results of 22 duplex studies were correlated with histopathologic data obtained between July 1987 and June 1988. RIs of the arcuate arteries in patients with acute rejection (n = 14) averaged 0.62 (range, 0.50-0.80). The RI in patients with chronic rejection (n = 1) was 0.59. RIs in patients with acute tubular necrosis (n = 3) averaged 0.66 (range, 0.59-0.72). RIs in patients with cyclosporine A toxicity (n = 4) averaged 0.66 (range, 0.58-0.79). Tubulointerstitial rejection was predominant, with only two patients showing minimal acute vascular rejection. Thirteen of 14 pediatric patients with histologically proved renal transplant rejection had a resistive index of less than 0.70. This study refutes the concept that resistive indexes of less than 0.7 exclude acute rejection.
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Leakage from the urinary bladder or duodenal stump after pancreas transplantation with urinary bladder drainage of the graft is difficult to diagnose clinically. We retrospectively reviewed our experience with fluoroscopic cystography and CT to determine their relative merit in the diagnosis of pancreatic fluid and urine leakage as documented by surgical exploration in pancreas transplant recipients. Thirteen leaks were diagnosed by fluoroscopic cystography or by CT in 11 patients after pancreas transplantation with urinary bladder drainage of pancreatic fluid. Conventional retrograde fluoroscopic cystography showed 11 leaks; CT with retrograde bladder opacification showed three leaks. Of the five CT studies that did not show a leak and that also were done within 7 days of a cystogram with abnormal findings, failure to use retrograde bladder opacification accounted for the majority (three cases) of missed diagnoses. Focal or free peritoneal abdominal fluid was seen in all CT examinations, with extravasation of contrast material seen into both walled-off collections and free ascites. Our experience suggests that retrograde bladder and duodenal stump opacification should be a routine part of the CT evaluation performed to detect leakage from the urinary bladder or duodenal stump after pancreas transplantation.
Hepatic transplantation is now a relatively commonplace procedure, performed at many institutions around the world. Assessment of transplant candidacy and posttransplantation complications relies heavily on radiologic studies. After transplantation, radiographic evaluation is especially important as the clinical presentation and laboratory findings of many complications are nonspecific. Additionally, therapeutic radiologic intervention is often beneficial in the management of posttransplantation complications. This article reviews the role of imaging in hepatic transplantation. It focuses on the capabilities of noninvasive and invasive imaging modalities in the evaluation of potential hepatic transplant candidates and in hepatic recipients, and it also reviews the application of interventional radiologic procedures to posttransplantation complications.