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Spontaneous dissection of the superior mesenteric artery (SMA) is a rare occurrence, especially when not associated with aortic dissection [1]. Currently, only 28 cases appear to have been reported. Due to the scarcity of cases in the literature, the natural history of isolated, spontaneous SMA dissection is unclear. CT has been reported to be useful for the initial diagnosis of SMA dissection [2-5]. We present two recent cases of spontaneous SMA dissection in which enhanced spiral CT was instrumental in following the disease process and guiding clinical decision making.

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PURPOSE: To compare the frequency and extent of pulmonary embolism (PE) occurring during pulse-spray pharmacomechanical thrombolysis (PSPMT) of clotted hemodialysis grafts with use of either urokinase (UK) or heparinized saline (HS). Postintervention primary patency and complication rates were compared for each method of thrombolysis. METHODS AND MATERIALS: Twenty-seven patients were enrolled in this prospective, randomized, double-blind study evaluating PE with two PSPMT agents. The doses of heparin were similar between groups. The only variable was that one group of patients received UK and the other received HS. In two cases, the venous anastomosis could not be crossed. Eleven patients were treated with UK and 14 with HS. Nuclear medicine perfusion lung scans were performed before treatment and after graft declotting procedures. Lung perfusion was quantified to 10% of a pulmonary segment (0 = normal perfusion, 1 = segmental perfusion defect), with nine segments counted for each lung. RESULTS: Baseline nuclear medicine perfusion lung scan results were abnormal (> or = 20% segmental perfusion defect) in 19 patients (70.4%). New PE (one or more pulmonary segments) occurred in two patients treated with UK (18.2%) and nine patients treated with HS (64.3%; P = .04). All cases of PE were asymptomatic. Quantitative global pulmonary perfusion analyses revealed that treatment with UK improved flow to 0.2 +/- 2.0 pulmonary segments, whereas treatment with HS decreased perfusion to 1.0 +/- 1.7 segments (P = .16, NS). Although postintervention primary patency rates were similar according to life-table analysis (P = .76, NS), complication rates were higher with use of HS (n = 4, 28.6%) than with use of UK (n = 2, 18.2%) (P = .6, NS). CONCLUSIONS: All PE were asymptomatic during PSPMT, but treatment with UK reduced the rate of PE and tended to result in smaller defects in lung scan results. Most patients undergoing hemodialysis have abnormal baseline perfusion scan results, but PSPMT with UK improved many of them. The postintervention primary patency rates were similar between groups, but complications were more frequent after treatment with HS.

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OBJECTIVE: The purpose of this study was to assess the efficacy of repeated pulsed spray pharmacomechanical thrombolysis for salvage of early rethrombosis of hemodialysis grafts and to identify factors that predict successful outcome. MATERIALS AND METHODS: Thirty-four patients with initial successful thrombolysis were referred for repeated thrombolysis because of early rethrombosis. Repeated thrombolysis occurred within 1 month of initial thrombolysis. Technical success and patency rates were calculated. Causes of graft thrombosis and procedural modifications were analyzed. RESULTS: The 39 rethrombosed grafts were successfully treated using pharmacomechanical thrombolysis, and patients underwent subsequent hemodialysis. The underlying flow-limiting stenoses were treated with balloon angioplasty using a larger balloon (41%), a same-size angioplasty balloon (18%), stent placement (15%), or increased anticoagulation (5%). A new stenosis location was discovered in 18%. Mean primary patency was 80.9 days (2.6 months) and secondary patency was 235.4 days (7.8 months). With life table analysis, 1-, 3-, 6-, and 12-month primary patency rates were 72%, 31%, 23%, and 15%, and secondary patency rates were 77%, 62%, 51%, and 31%, respectively. Graft patency rates in our study were compared with our institutional historic graft patency rates, with no significant difference noted (p = 0.76). No major procedural complications occurred. CONCLUSION: Adequate technical success and patency rates for pharmacomechanical thrombolysis occur even for hemodialysis grafts that rethrombose within 1 month. After thrombolysis, aggressive search for and treatment of additional stenoses are warranted.

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PURPOSE: To evaluate the safety and efficacy of a minipercutaneous nephrolithotomy procedure (mini-PCNL) through a 20F sheath. PATIENTS AND METHODS: Twenty-one patients underwent a mini-PCNL from October 1997 to October 1999. The mean number of calculi was 1.8 (range 1-9). The mean cross-sectional area of the stone burden was 2.8 cm2 (range 0.72-6.5 cm2). Nephrostomy tract dilation was performed with an 18F Cook Omega or Pursuit balloon dilation catheter (6-mm diameter, 10-cm length; 12 or 14 atm, respectively), and a 20F nephrostomy sheath was advanced over the inflated balloon. RESULTS: The mean operative time was 54 minutes. The mean decrease in hematocrit was 3.4%, and no patient required a blood transfusion. The mean percutaneous tube duration was 22 hours. The mean hospital stay was 1.1 days. The single-procedure stone-free rate was 90%. Two patients underwent successful SWL of residual middle-caliceal calculi that could not be accessed through the existing tract. There were no major complications, but there was one episode of prolonged fever secondary to atelectasis. Five patients remain free of radiographic or symptomatic recurrence after antegrade endopyelotomy for ureteropelvic junction obstruction after a mean of 11 months' follow-up. CONCLUSIONS: By using a 20F sheath rather than the traditional 30F sheath, we decreased the volume of renal parenchyma that is dilated by 56%. This change appears to decrease perioperative bleeding and pain as well as parenchymal scarring.

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PURPOSE: To evaluate the usefulness of information provided by three-dimensional ultrasound (3D US) and to determine whether 3D US decreased the number of passes required to obtain portal vein (PV) access during creation of transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Intermittent 3D US volume acquisitions were obtained during creation of TIPS in 20 patients. Useful information provided by 3D US was tabulated. The number of passes required to achieve PV access was recorded and results were compared retrospectively to 25 patients who underwent TIPS without 3D US. RESULTS: 3D US documented that the operator's opinion of which hepatic vein had been selected was incorrect in nine patients (45%), detected unfavorable PV anatomy that required modification of equipment or technique in seven patients (35%), permitted estimation of the trajectory required to access the targeted PV in all patients (100%), assisted in selecting the optimal point along the hepatic vein for origination of the needle pass in 11 patients (55%), allowed avoidance of a large hepatocellular carcinoma in one patient (5%), and confirmed that access into the main PV was intrahepatic in four patients (20%). The mean number of needle passes decreased from 10.4 in the historic control group to 4.6 in the 3D US group (P = .0001). CONCLUSION: 3D US provided imaging information that detected technical errors and altered anatomy, and provided positional and directional information to significantly improve needle pass efficiency.

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PURPOSE: To evaluate the usefulness of information provided by three-dimensional ultrasound (3D US) and to determine whether 3D US decreased the number of passes required to obtain portal vein (PV) access during creation of transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Intermittent 3D US volume acquisitions were obtained during creation of TIPS in 20 patients. Useful information provided by 3D US was tabulated. The number of passes required to achieve PV access was recorded and results were compared retrospectively to 25 patients who underwent TIPS without 3D US. RESULTS: 3D US documented that the operator's opinion of which hepatic vein had been selected was incorrect in nine patients (45%), detected unfavorable PV anatomy that required modification of equipment or technique in seven patients (35%), permitted estimation of the trajectory required to access the targeted PV in all patients (100%), assisted in selecting the optimal point along the hepatic vein for origination of the needle pass in 11 patients (55%), allowed avoidance of a large hepatocellular carcinoma in one patient (5%), and confirmed that access into the main PV was intrahepatic in four patients (20%). The mean number of needle passes decreased from 10.4 in the historic control group to 4.6 in the 3D US group (P = .0001). CONCLUSION: 3D US provided imaging information that detected technical errors and altered anatomy, and provided positional and directional information to significantly improve needle pass efficiency.

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Three different femoral artery flow velocity parameters in combination with segmental pressure measurements were evaluated for their respective diagnostic value in identifying the presence or absence of hemodynamically significant aorto-iliac disease. A total of 60 patients (119 legs) were examined both non-invasively and with arteriography. Doppler flow velocities were recorded using a 5-MHz CW Doppler velocity metering system. Of the three parameters used (peak velocity, decay time and deceleration), a decay time of 220 ms yielded the most practical discriminant value. The accuracy increases when in addition the upper thigh/arm pressure ratio values are considered. The results indicate that the combination of femoral artery decay time with the upper thigh/arm pressure index provides a simple and accurate non-invasive screening method to confirm or rule out aorto-iliac disease. This helps to determine whether the patient is a candidate for arteriography and for potential surgical intervention.

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PURPOSE: A comparison of tilting, caval coverage, asymmetry, and insertion problems with the over-the-wire stainless-steel and titanium versions of the Greenfield filter. MATERIALS AND METHODS: The study compared 104 stainless-steel and 141 titanium Greenfield inferior vena cava (IVC) filter insertions. The angle the sheath and deployed filter made relative to the cava, as well as filter strut distribution, were determined from spot films. The proportionate caval coverage was computed from the cavogram (anteroposterior projection). Mean filter tilts, subgrouped by insertion site, and caval coverage were compared with the Student t test, whereas strut patterns were analyzed with a contingency table. RESULTS: The filter caval and sheath caval angles correlated. The filter caval angles varied with insertion site, but were lowest with a right jugular approach. Caval coverage was identical with both designs. The stainless-steel version resulted in a more uniform distribution of struts in comparison with the titanium version. The incidence of insertion problems was not significantly different between the filter types. CONCLUSIONS: While IVC filter tilting was not improved with the newer design, the pattern of struts was more uniformly symmetric with the stainless-steel device. The right jugular insertion site was associated with the lowest filter caval angles and the most symmetric pattern of struts.

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PURPOSE: To determine whether acute cervical spine injury represents a risk factor for complications from prophylactic placement of current generation Greenfield inferior vena cava (IVC) filters. MATERIALS AND METHODS: A retrospective chart review performed during a 7-year period identified 11 patients with acute cervical spinal cord injuries who underwent prophylactic Greenfield IVC filter insertion. Specific complications evaluated included symptomatic pulmonary embolism (PE), migration, filter base diameter changes, caval perforation, and thrombosis. The amount of migration and changes in filter base dimension were compared statistically with a control population of IVC filter patients (n = 16) without cervical spine injuries. RESULTS: Filter migration (> 10 mm) was the most common complication (46%). Migration usually is caudally directed (64%), may occur early (36% moved > 10 mm within a 30-day period), and is often asymptomatic. The prevalence of filter migration greater than 30 mm was 27%. The average amount of migration for the subpopulation under study was greater than that seen with the control population (P < .05). No statistically significant change in filter base size occurred. The study population also had rates of PE (9%-18%), caval perforation (9%), and IVC thrombus formation (18%) that were higher than the rates in historical controls. The majority of patients with these complications received vigorous pulmonary toilet (46%), including "quad coughs" or cardiopulmonary resuscitation (18%). CONCLUSIONS: Acute cervical spinal cord injury and the associated supportive care may be associated with an increased risk for caudal IVC filter migration, IVC perforation, caval thrombosis, and PE.

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PURPOSE: To determine the value of a hemodialysis graft surveillance program in reducing the incidence of graft thrombosis and prolonging graft patency by means of early detection and percutaneous transluminal angioplasty (PTA) of graft-related stenoses. MATERIALS AND METHODS: For 4-1/2 years, routine graft examination and measurement of several dialysis parameters were used to identify 106 cases of suspected graft dysfunction in 57 patients (56 men, one woman; aged 27-76 years). Graft-related stenoses detected with angiography were treated with PTA. RESULTS: Abnormal physical examination findings were the most common sole indication of graft dysfunction. Of the 106 cases referred for angiographic evaluation, 97 (92%) had at least one lesion. PTA was successful in 88 of 90 treated cases. The primary patency rates at 1 year were 16% for arteriovenous fistulas (AVFs) and 23% for polytetrafluoroethylene (PTFE) grafts. Early detection of stenoses by means of surveillance and repeated PTA enabled 1-year primary assisted patency rates of 67% for AVFs and 68% for PTFE grafts. The incidence of graft thrombosis fell from 48% in 1988 to 17% in 1994 (P < .001). CONCLUSION: The hemodialysis graft surveillance program resulted in a statistically significant reduction in the incidence of graft thrombosis. Although primary patency rates after PTA were low, repeated PTA of detected stenoses allowed good primary assisted patency rates.

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PURPOSE: To assess the efficacy and safety of percutaneous catheter drainage combined with alcohol sclerosis in the treatment of postoperative lymphoceles. PATIENTS AND METHODS: Thirteen patients with 14 postoperative symptomatic lymphoceles were treated. Drainage catheters were inserted under ultrasound (n = 13) or computed tomographic (n = 1) guidance. Lymphocele sclerosis was performed by instilling 10-100 mL of absolute alcohol into the lymphocele cavity and aspirating the alcohol after 30 minutes. Sclerosis sessions were carried out one to three times per day, usually three times per week. Catheter sinograms were obtained and prophylactic antibiotics administered. Imaging was repeated if symptoms or signs of recurrence developed. RESULTS: Successful drainage and sclerosis were achieved in all 13 patients. One patient with a recurrence was successfully treated with repeated drainage and alcohol ablation. No adverse effects of alcohol instillation were seen. The mean duration of catheterization was 36 days (range, 17-65 days; median, 30 days). CONCLUSION: Percutaneous drainage combined with alcohol ablation is a safe and effective treatment of postoperative lymphoceles.

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Our study was aimed at comparing the therapeutic efficiency of single and double lumen catheters in the drainage of abdominal fluid collections. We report the results of in vitro and in vivo studies carried out to assess the usefulness of each catheter type based on its therapeutic results. In the in vitro study the aspiration efficacy of the catheters was tested in a simulated cavity. In the in vivo study 188 patients with 206 fluid collections in the abdomen were examined; the patients had been treated percutaneously with single or double lumen catheters, randomly. In each patient we studied drainage efficiency related to aspiration efficacy, the time the catheter rested in the cavity, patient's discomfort and finally the cost of both the device and hospitalization. Some patients underwent surgery for specific reasons, but nevertheless their clinical conditions were absolutely improved thanks to percutaneous drainage. The results of this study yield useful clinical data to choose the most suitable catheter for the percutaneous treatment of abdominal fluid collections. Single lumen catheters work better than double lumen ones, the latter being also more expensive. Hospitalization time is also reduced when single lumen catheters are used.

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