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PURPOSE: To evaluate the healing characteristics of stents versus endovascular grafts in the porcine iliac artery. MATERIALS AND METHODS: A total of 20 iliac arteries in 10 domestic swine were used to evaluate the healing characteristics of stents versus endovascular grafts. Each animal received one stent and one endovascular graft in opposite iliac arteries. The endovascular grafts were constructed with use of 6 cm of expanded polytetrafluoroethylene (ePTFE) (3 mm inner diameter, 30 microm internodal distance) and Palmaz stents (P204 or P188) secured at each end of the graft. A solitary Palmaz stent (P308 or P294) was used on the opposite side. The devices were explanted at 1, 5, and 12 weeks. RESULTS: One of three endovascular grafts and two of three stents were patent at 1 week. Two of three endovascular grafts and all three stents were patent at 5 weeks. All three endovascular grafts and stents were patent at 12 weeks. Gross examination, histologic, and scanning electron microscopy demonstrated differences in the healing response of the two devices. A marked abluminal inflammatory response to the graft material was observed. This resulted in neovascularization of the tissue along the abluminal surface of the graft. In addition, marked neointimal thickening at the unsupported section of the endovascular graft resulted in significant luminal narrowing. CONCLUSION: The porcine model may be used for evaluating the healing characteristics of endovascular grafts. Intravascular placement of ePTFE prosthetic graft material dramatically alters the healing of this type of graft material. The graft material did not prevent the formation of a progressively thickening neointima.

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PURPOSE: The increased use of thrombectomy with deliberate pulmonary embolization of thrombus following initial thrombolysis for occluded hemodialysis fistulas prompted the authors to measure the prevalence of pulmonary embolism (PE) due to the procedure. PATIENTS AND METHODS: Thirty-one patients with 43 acutely thrombosed polytetrafluoroethylene hemodialysis fistulas were treated with thrombolysis/thrombectomy. Perfusion lung scans were obtained in 22 patients. Patients were also continuously monitored for clinical signs or symptoms of PE. RESULTS: Perfusion scans were interpreted as consistent with PE in 59% of those studied, but no clinical signs or symptoms were present in 41 of the 43 cases (95%). However, two patients developed both signs and symptoms of acute PE in the postprocedural period and died. One had underlying pulmonary disease and had undergone thrombectomy before. The other had chronic heart disease. CONCLUSION: Thrombolysis/thrombectomy is usually safe and effective, even though many patients develop subclinical PE. The authors urge extreme caution in patients who have underlying pulmonary or cardiac disease and/or have undergone the procedure before.

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To better understand the use of magnetic resonance angiography (MRA) in evaluating peripheral vascular disease, the authors studied arteries in the foot and ankle. Twenty patients with arterial occlusive disease of the lower extremity were studied with two-dimensional time-of-flight MRA, and the results were compared with those of 10 conventional x-ray arteriograms, four digital subtraction arteriograms, and three intraoperative arteriograms. The studies were reviewed and rated by three radiologists blinded to the patients' clinical history. Also, the first 16 patients were examined with MRA before and after intravenous injection of gadopentetate dimeglumine. The mean confidence levels for the reviewers' interpretations of the MRA studies were significantly higher than those for the conventional arteriograms for the medial plantar, lateral plantar, and plantar arch arteries of the feet (P < or = .005). Postcontrast MRA images were inferior to precontrast images because of overlapping of veins and arteries. Time-of-flight MRA without gadolinium can serve as a useful complementary study for evaluating patients with peripheral vascular disease in the foot and ankle.

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Catheter-directed thrombolysis was used either alone or as an adjunct to percutaneous transluminal angioplasty (PTA) or surgery for peripheral vascular occlusion on 112 occasions in 102 patients. Symptom duration ranged from < one to > twenty-eight days. Thrombolytic therapy using urokinase plasminogen activator thrombolysis (uPAT), including intrathrombic injection when possible, was successful (> 50% lysis) in 99 procedures (88%). Technical failure (< 50% lysis) occurred in 13 procedures (12%). In 9 of the 13 failures, intrathrombic injection of urokinase was not possible, but the duration of occlusion was > twenty-eight days in all but 1. Two other failures were from embolic sources and 2 more occurred in patients with a hypercoagulable state. The uPAT was adjunctive to PTA/surgery in 56 cases (50%). PTA following uPAT was required and successfully performed in 24 of 27 cases (88.9%). Surgery followed lytic therapy in another 32 (including the 3 failed PTAs). In the remaining 56 cases (50%), no additional intervention was required. There were 20 complications (18%), minor in 16 of 20 (80%). Minor complications included small puncture site hematomas and distal embolization resolved by continued lytic therapy. Four major complications occurred. One was retroperitoneal hemorrhage directly contributing to the only death in the series. The other 3 were hematuria (2) and femoral neuropathy (1). The authors conclude that catheter-directed lytic therapy alone or as an adjunct to PTA/surgery is a valuable approach to peripheral vascular thromboembolic disease. It is less likely to succeed in chronic occlusion. The incidence of complications is moderate but acceptable.

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Hepatic arterial chemoembolization (CE) with a mixture of particulate collagen and chemotherapeutic agents was evaluated as therapy for hepatic metastases from colorectal carcinoma. This article describes the characteristics sequential pattern of change seen on liver CT scans following CE. Thirty CT scans were performed on seven patients who had undergone a total of 11 CE procedures. All patients had baseline, immediate postprocedural, and follow-up CT exams at 1 to 2 month intervals following CE. Immediate post-procedural CT scans mapped the area of embolization owing to the density of the contrast mixed with the CE agents. Some lesions seen easily on baseline were more difficult to see as they became isodense with normal liver. Reflux of embolic material into the cystic artery and gallbladder wall was also observed on postprocedural scans in three patients. In all patients, early follow-up scans (1 month after CE) demonstrated changes in lesions seen on baseline scans consistent with tumor necrosis. This was corroborated by a decrease in carcinoembryonic antigen (CEA) levels. In three patients, however, low attenuation regions developed in areas in which there had been no lesion before. The significance of these is uncertain, but the low CEA values and the subsequent evolution in appearance of these sites on CT suggest that they were regions of hepatic ischemia/infarction as opposed to heretofore unidentifiable metastases, now "unmasked." Intermediate follow-up scans (2-3 months) revealed maximal effect on tumor volume, with a decrease of > or = 25% in five of seven patients (71%). Late follow-up scans (> or = 3 months after the last CE) confirmed recurrent disease and new lesions in all cases.

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The results of 170 emergency arteriography procedures in 142 patients who had sustained extremity injuries near major arteries were correlated with the findings from a physical examination conducted prior to arteriography. Radiographically demonstrable significant arterial injuries, which usually required surgical repair, were present at 42 of the 170 injury sites (25%). Major physical findings suggestive of arterial injury were noted at 105 of 170 sites (62%). Arteriography demonstrated a significant injury in 40 (38%) of these 105 injury sites, representing 95% of all major arterial injuries. Among the 65 injury sites without any suggestive major physical finding, only two were associated with a significant vascular injury at arteriography (3%) (5% of all 42 arterial injuries). At each of these 65 injury sites, the decision to perform emergency arteriography was based solely on the proximity of the wound to a major artery. In spite of this very low yield in the subgroup of 51 patients without major physical findings, emergency arteriography is still routinely requested for extremity injuries at the authors' institutions. The validity of this policy, a possible reason for its development, and its effect on patient disposition are examined.

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Intraarterial urokinase (IAUK) was administered to 33 patients on 40 occasions for the treatment of acute extremity ischemia and long-term patency was assessed. Lysis was successful in 39 of the 40 cases (95%). Occlusive thrombus was cleared in 12 of 13 patients with native artery occlusion (7 complete, 5 partial), 8 of 9 with autologous vein grafts (5 complete, 3 partial), and in all 18 patients with synthetic grafts (17 complete, 1 partial). The primary cumulative patency following successful IAUK was 100% for native arteries and 47% for synthetic grafts at 12 months, and 23% for autologous grafts at 9 months. The difference in rethrombosis rate between autologous vein (67%) and native artery (0%) was significant (p = 0.02) as was the difference between infrainguinal prosthetic grafts (63%) and native artery (p = 0.025). IAUK is most effective for the treatment of native artery occlusion, but is significantly less effective for thrombosed infrainguinal autologous vein or synthetic grafts due to the likelihood of reocclusion, despite the high immediate success rate. For autologous vein grafts, lysis is frequently incomplete and patency rapidly deteriorates regardless of adjunctive therapy to relieve the underlying obstruction.

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Severe cutaneous ulceration may occur as a result of contrast media extravasation. We established a definitive animal model for assessing the cutaneous toxicity of commonly employed agents and used this model to evaluate possible antidotes to the effects of contrast media extravasation. The contrast agents studied were: meglumine/sodium diatrizoate 76%, meglumine iothalamate 60% and 43%, meglumine/sodium ioxaglate 60%, iohexol 350, and iopamidol 370, in varying volumes and osmolalities. Hypertonic saline (950 and 1900 mOsm/kg) also was injected. Agents were injected intradermally into BALB/c mice. The higher osmolality agents produced dose-dependent skin ulcerations. The lower osmolality agents failed to produce any skin lesions after the same volume doses. Hypertonic saline produced skin toxicity in a dose-dependent fashion similar to hyperosmolar contrast agents. Three antidotes were tested: hyaluronidase, topical heat, and topical cold. Hyaluronidase significantly reduced skin toxicity when injected immediately following contrast injection. Cold also significantly reduced skin toxicity, while heat caused no improvement.

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Most publications citing the effectiveness of renal extracorporeal shock wave lithotripsy have used plain abdominal radiography to assess residual calculi after treatment. We compared radiologist sensitivity and specificity in the detection of calculi on plain abdominal radiographs versus conventional film-screen and digital renal tomograms in extracorporeal shock wave lithotripsy patients. Of the patients 50 were imaged before and within 24 hours after lithotripsy. Six radiologists evaluated the resultant 300 studies for the presence and location of calculi. The mean sensitivity for digital tomograms was 83% for pre-lithotripsy and post-lithotripsy studies, which was significantly higher than for plain abdominal radiography and conventional tomography after lithotripsy. However, there were significantly more false positive stone diagnoses associated with digital tomogram interpretation. Signal detection analysis verified the over-all superiority of digital tomography for post-extracorporeal shock wave lithotripsy imaging. Calculus detection by conventional and digital tomography is superior to detection by plain abdominal radiography. However, because we did not perform delayed imaging, it is not possible to say what impact digital tomography might have on the management of extracorporeal shock wave lithotripsy patients.

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Although restricted transhepatic portal flow is necessary for development of generalized portal hypertension (GPH), increased splanchnic arterial inflow also contributes to GPH and its clinical sequelae. In this context, we describe 7 male and 6 female patients (mean age 48 years) in whom the lesser splanchnic (gastrosplenic) system played a key role in the signs and symptoms of GPH. These 13 patients (9 with hepatic cirrhosis, 3 with primary myeloproliferative disorder, and 1 with extrahepatic portal block) shared common features of massive splenomegaly, huge splenofundic gastric varices, often with a prominent natural shunt to the left renal vein. Total or near total splenectomy alone or combined where appropriate with coronary vein ligation was effective in controlling varix hemorrhage (10 patients), ascites (3), or complications of an enlarged spleen-anorexia and abdominal pain (3), hemolytic anemia (1) and profound thrombocytopenia with severe epistaxis (1). Intraoperative jejunal portal venography was crucial in operative management in order to establish definitively the presence or absence of coronary venous collaterals, and when present, to verify their operative ligation. These distinctive patients illustrate: 1) GPH is a heterogeneous syndrome of divergent splanchnic circulatory patterns, a feature which should be taken into account in selecting operative treatment; 2) one well-defined subgroup displays prominent hyperdynamic lesser splanchnic and specifically, splenic blood flow as a major contributor to clinical complications; and 3) within this subgroup, splenectomy combined with documented absence or surgical interruption of coronary venous collaterals as corroborated by intraoperative portography is effective alternative treatment.

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In 20 patients with congenital and acquired lymphedema in either upper or lower extremities and in four patients without extremity edema, human serum albumin labeled with technetium-99m was injected intradermally into a digital web space of the hand or foot. With a digital gamma camera that permitted a "sweep" of the torso, serial extremity and whole-body lymphagioscintigraphy (LAS) of the peripheral lymphatic system was performed. In 11 patients with acquired lymphedema, a well-defined obstructive pattern was seen, characterized by discrete peripheral lymphatic trunks, delayed or absent depiction of regional nodes, and delayed but extensive soft-tissue tracer extravasation. Five of nine patients with congenital lymphedema showed hypoplasia characterized by poorly defined lymphatic trunks, delayed depiction of regional nodes, and early and extensive extravasation of tracer. The other four patients showed aplasia, with absence of trunks, no depiction of nodes, and little or no tracer extravasation. LAS is technically simple to perform and requires no special training. Radiation exposure is minuscule, and the procedure is safe and without apparent side effects. For these reasons, whole-body LAS should be the preferred method for the initial assessment of congenital or acquired lymphedema.

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To investigate radiologists' performance at interpreting digital radiographic images, we compared the detectability of pneumothoraces on computed radiographic chest images with 0.2-mm pixel size (2.5 Ip/mm) with their detectability on matched conventional screen-film images (5 Ip/mm). Eight radiologists reviewed 50 computed and 50 screen-film chest radiographs from 25 patients with pneumothoraces and 25 patients with other (or no) abnormalities. Four of the readers who best detected pneumothoraces on screen-film examinations performed worse when interpreting computed radiographic studies; the other four readers detected pneumothoraces similarly with both techniques. No relationship was found between the size of a pneumothorax and its likelihood of detection by either technique. These results raise concerns about implementing computed radiography for comprehensive chest imaging.

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This prospective study compared images obtained with a photostimulable imaging plate with matched images obtained with a conventional screen-film combination in 26 patients undergoing intraoperative arteriography. Diagnostic accuracy of the two techniques was assessed objectively, and image quality was assessed subjectively. In 16 patients (62%), the radiation exposure was reduced by 50% for the imaging plate technique by decreasing the mAs level generally used for the screen-film combination. Because of the dynamic range of the imaging plate system, no repeat examinations were necessary, while 12% of the screen-film studies had to be repeated because of over- or under-penetration. Imaging plate studies required 6% more time for processing than screen-film studies. Receiver-operating-characteristic analysis indicated no difference in diagnostic accuracy between the two imaging techniques. Subjective evaluation also revealed no difference in observer preference for imaging plate or screen-film studies. The imaging plate technique is an excellent alternative to screen-film studies in the operating room.

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This prospective study assesses the contribution of lymphography (LAG), abdominal-pelvic computed tomography (CT), and bone marrow biopsy to the staging and management of 168 consecutive cases of newly diagnosed non-Hodgkin lymphoma (NHL). LAG and/or CT influenced Ann Arbor clinical stage (CS) in 39 patients (23%) and Ann Arbor pathologic stage (PS) in 23 patients (14%) by detection of clinically inapparent retroperitoneal adenopathy and/or extranodal disease. LAG findings raised the CS in eight patients and the PS in six of the eight by showing adenopathy when the CT results were negative. By depicting extranodal disease, CT resulted in the CS being raised in an additional ten patients and the PS in six of the ten. Of the diagnostic tests assessed, bone marrow biopsy and/or cytology had the greatest influence on staging. Clinical staging that included LAG/CT resulted in the identification of only 30 patients with CS IV disease, whereas an additional 53 CS I through CS III patients had their disease stage raised to PS IV due to positive bone marrow biopsy/cytology results. However, 42 of the 53 patients already had advanced (CS III) disease. Initial case management was influenced by LAG, CT, or bone marrow biopsy/cytology results in 27 of 168 patients. LAG/CT results influenced management in 20 of 27 cases, while bone marrow biopsy/cytology results caused initial management changes in only seven of the 27 cases.

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A total of 129 transtracheal aspirations or fine needle aspirations, or both, were performed in 65 heart and heart-lung transplant patients to identify the causative pathogen in suspected pulmonary infection. Transtracheal aspiration was performed in 82 instances, fine needle aspiration in 47, and both procedures in 23. Both transtracheal and fine needle aspiration were highly specific, 96% and 100%, respectively. Sensitivity for transtracheal aspiration was lower than for fine needle aspiration, 70% and 89%, respectively. The lower sensitivity of transtracheal aspiration is attributed to its performance in all patients with suspected infection regardless of chest radiographic findings. Fine needle aspiration was performed when identifiable lesions could be used as a "target." Overall accuracy of transtracheal aspiration was 78% compared to 91% for fine needle aspiration both alone and combined with transtracheal aspiration. More invasive procedures such as bronchoalveolar lavage and open lung biopsy were required in only three patients (2%). Transtracheal aspiration resulted in one minor complication (1%). The commonest complication of fine needle aspiration was pneumothorax (21%). There were no deaths associated with either procedure. We conclude that in heart and heart-lung transplant patients with suspected pulmonary infection, transtracheal aspiration and fine needle aspiration are safe and accurate methods to identify the causative organism. More invasive techniques may be required in a small minority of patients.

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