Transluminally placed endovascular grafts for venous lesions in patients on hemodialysis.

This report summarizes a feasibility study of transluminally placed endovascular grafts (TPEG) using pre-expanded polytetrafluoroethylene (PTFE) to treat venous abnormalities in patients on hemodialysis. Seventeen patients with peripheral (n = 11) or central (n = 6) venous lesions were treated with TPEG devices. Covered Gianturco stents were used for the peripheral lesions and covered Palmaz stents were used for central lesions. Venous abnormalities included vascular rupture after balloon angioplasty or surgical thrombectomy (n = 4), stenosis associated with an aneurysm (n = 2) and occlusive disease and central stenoses not responsive to balloon angioplasty (n = 11). The mean primary patency period was 37 days. The mean secondary patency period was 215 days. At 60, 180, and 360 days the primary and secondary patency rates were 40%, 32%, and 32%, and 70%, 55%, and 39%, respectively. Follow-up studies have shown various outcomes of the implanted TPEG devices, which have included stenoses within the TPEG (n = 2), stenoses central to the TPEG (n = 1), stenoses peripheral to the TPEG (n = 3), acute thrombosis extending to the TPEG without a stenosis (n = 1), graft abandoned with patent TPEG (n = 6), and TPEG patent within primary patency period at last follow-up (n = 4). The TPEG devices, made with pre-expanded PTFE, appear safe in the short term, do not prevent progressive dialysis access site failure, and need to be compared to PTA and endovascular stenting in a randomized prospective trial.

"Accordion" deformity of a tortuous external iliac artery after stent-graft placement.

PURPOSE: To identify a complication of endograft deployment in aneurysmal iliac arteries. CASE REPORT: A 71-year-old man was referred for endovascular treatment of a 60-mm-diameter right common iliac artery aneurysm; however, deployment of a homemade covered stent (Palmaz-Schatz and polytetrafluoroethylene) induced shortening of the tortuous external iliac artery, causing an "accordion" deformity. The anomaly proved difficult to treat with serial Wallstent deployment, because the convolution tightened and migrated caudally with each stent deployed, threatening outflow. Finally, after 3 Wallstents were implanted, the contour of the external iliac artery was straight, and flow was unimpeded. However, 3 weeks later, the external iliac artery had recoiled to its original redundant appearance, but flow remained satisfactory. The aneurysm remains excluded, with satisfactory distal flow after 24 months. CONCLUSIONS: Implanting endografts in redundant, tortuous arterial segments may prove problematic, since induced straightening by the device precipitates kinking in the redundant system. Although treatment may be required in some situations, the vessels may return to a noncompressed state by removing the delivery system and guidewire.

Transluminally placed endovascular grafts to exclude undesirable intracardiac vascular communications.

PURPOSE: In this report, we summarize our early experience using transluminally placed endovascular grafts (TPEG) to close intracardiac communications within surgically created conduits. MATERIALS AND METHODS: Three patients with surgically corrected congenital heart disease were treated in this study. All three patients had intracardiac conduits [Modified Fontan (n = 2) or Mustard procedure (n = 1)]. All three patients had intracardiac shunts causing hypoxemia. The shunts were caused by a surgically created fenestration (n =1), a leak at a surgical anastomosis (n = 1) and perforations of a pericardial baffle (n = 1). All three patients were treated percutaneously from venous side approaches. The TPEG devices were constructed of pre-expanded polytetrafluoroethylene (PTFE) sutured to a Palmaz stent. RESULTS: In the two patients with the modified Fontan procedures, the leaks were completely excluded; in the patient with the Mustard procedure, the perforations in the baffle were not completely excluded. All patients experienced immediate improvements in oxygen saturation ranging from 17Eth 26% (mean, 20.3%). The improvements in oxygen saturation were sustained with values ranging from 12Eth 22% (mean, 17.3%) at the time of clinical follow-up. Clinical follow-up has ranged from 13Eth 19 months (mean, 15 months) and has demonstrated improved exercise tolerance and weight gain. Echocardiographic follow-up has shown no complications of TPEG stenoses, occlusions or migrations. There were no immediate or delayed complications associated with the TPEG devices. CONCLUSION: We report our experience using TPEG devices to exclude intracardiac communications in 3 patients with surgically corrected congenital heart disease. The preliminary results are encouraging and suggest that further investigation in this area should be done.

Helical CT in the evaluation of renal colic.

This study assessed the clinical effectiveness of unenhanced helical (spiral) computed tomography (CT) for evaluation of patients presenting with symptoms of renal colic. Two hundred patients with symptoms and signs of renal colic (flank or groin pain, hematuria) were imaged. Unenhanced CT was performed using 5-mm collimation with a pitch of 1.5 to 1.8. Image reconstruction was performed at 3-mm intervals. Exam time was approximately 5 minutes. The financial charge at the study institution was the same as for an intravenous urogram. Clinical follow-up was performed by review of available medical records and patient interviews. The sensitivity for detecting clinically relevant ureteral and bladder calculi was 0.862 (0.95 confidence interval [CI] 0.771 to 0.927), the specificity was 0.914 (0.95 CI 0.837 to 0.962), and the accuracy was 0.89 (0.95 CI 0.833 to 0.931). Helical CT is an effective technique in the evaluation of suspected acute urinary tract obstruction.

Single limb patency of polytetrafluoroethylene dialysis loop grafts maintained by traumatic fistulization.

The purpose of this report is to describe an unusual presentation of obstructive neointimal hyperplastic lesions in loop prosthetic dialysis grafts. The case histories and imaging studies of two patients with partial graft thrombosis are presented. The literature of unexpected fistulae from prosthetic dialysis grafts to adjacent veins is reviewed. Signs and symptoms that would lead a clinician to suspect the diagnosis are emphasized. There were two dialysis grafts with partial thrombosis and arterial limb patency maintained by iatrogenic fistula. These fistulae occurred from the erosion of pseudoaneurysms in one case and an apparent needle stick without pseudoaneurysm in the other. Both grafts had high-grade stenotic lesions affecting the venous outflow. In the first case this was not recognized until the graft reclotted 2 days after thrombectomy. In the most extreme cases of graft/vein fistulae, i.e., partial graft thrombosis with arterial limb patency maintained by the fistula there is always associated venous anastomotic or outflow stenoses which must be addressed.

Aortic and lower-extremity arterial disease: evaluation with MR angiography versus conventional angiography.

PURPOSE: To compare magnetic resonance (MR) angiography with conventional angiography in evaluation of the aorta and lower-extremity arterial system. MATERIALS AND METHODS: Fifty-seven patients were evaluated with femoral conventional and MR angiography. Iliac artery segments were evaluated with two-dimensional and contrast material-enhanced three-dimensional time-of-flight MR angiography. Infrainguinal regions were evaluated with two-dimensional time-of-flight MR angiography with a dedicated lower-extremity coil. Arteries depicted on femoral images were separately interpreted as 20 anatomic segments. Disease classification included normal to moderate disease (0%-50% stenosis), severe stenosis (> 50% stenosis), diffuse disease (more than one severe stenosis), and occlusion. Four readers interpreted the images and rendered treatment recommendations. RESULTS: Substantial to almost perfect interobserver agreement (kappa, 0.66-1.00) was achieved in most cases for MR angiogram interpretation. The three most experienced readers achieved substantial to almost perfect intraobserver agreement (kappa, 0.61-1.00) between conventional and MR angiogram interpretation in most cases. Among three readers, moderate agreement (kappa, 0.43-0.53) was found between treatment recommendations based on conventional versus MR angiographic findings; for the most experienced reader, this agreement was almost perfect (kappa, 0.90). CONCLUSION: For experienced readers, there was substantial to almost perfect agreement between conventional and MR angiographic image interpretations of the aorta and lower-extremity arterial system.

The answer is blowing in the wind: a pedunculated tumour with saw tooth flow-volume loop.

Obstructing tumours of the upper airways have been demonstrated to alter the flow volume loop of pulmonary function testing. These alterations could be clues to the nature and location of the obstruction. This report describes a case of a pedunculated squamous cell carcinoma arising in the pharynx whose flow volume loop showed a saw tooth pattern which reflected the location and structure of the tumour.

Endovascular stents covered with pre-expanded polytetrafluoroethylene for treatment of iliac artery aneurysms and fistulas.

PURPOSE: This report describes the early clinical experience with use of a transluminally placed endovascular graft (TPEG) covered with pre-expanded polytetrafluoroethylene (PTFE) to treat iliac artery aneurysms and fistulas. MATERIALS AND METHODS: Eight patients with iliac artery aneurysms (n = 7) and common iliac artery to common iliac vein fistula (n = 1) were treated with TPEGs. The iliac artery aneurysms were either common iliac (n = 6) or hypogastric (n = 1). All of the patients had significant comorbid diseases. The TPEG devices were made with pre-expanded PTFE sutured to Palmaz stents and delivered through 10- or 12-F sheaths. RESULTS: The aneurysms were successfully excluded in six of seven patients and the one iliac artery-to-vein fistula was successfully occluded. There were no immediate procedural complications related to the TPEG devices. Follow-up was limited (mean, 12 months), but no stenoses or occlusions of the TPEG devices were detected. The one failure was probably due to the marked tortuousity of the iliac artery, which prevented an adequate seal. CONCLUSION: In the authors' early clinical experience, the use of TPEG devices with pre-expanded PTFE successfully treated iliac artery aneurysms and an iliac artery-to-vein fistula. Although the results are encouraging, longer follow-up is necessary to better evaluate this type of treatment.

MR imaging of the rotator cuff tendon: interobserver agreement and analysis of interpretive errors.

PURPOSE: To evaluate accuracy in interpretation of shoulder magnetic resonance (MR) images and interobserver agreement and to characterize the types of errors. MATERIALS AND METHODS: Five radiologists with varying experience independently and retrospectively twice interpreted the MR images of 222 symptomatic patients who underwent both MR imaging and shoulder arthroscopy. The first interpretation was a blind review; the second was with knowledge of the arthroscopic findings. RESULTS: For full-thickness tears, the sensitivity, specificity, and accuracy were 84%-96%, 94%-98%, and 92%-97%, respectively, and for partial tears, 35%-44%, 85%-97%, and 77%-87%, respectively. There was no statistically significant difference between readers in the detection of partial or full-thickness tears. There was a statistically significant difference between readers in the no-tear category. Cohen kappa values generally indicated improved interobserver agreement proportional to the readers' experience (full-thickness tears, 0.731-0.881; partial tears, 0.168-0.443). CONCLUSION: Diagnosis of a full-thickness tear can be learned to a high degree of accuracy. Despite the radiologist's level of experience and knowledge of the arthroscopic findings, the sensitivity for diagnosis of partial tears is poor.

Evaluation of the iliac arteries: comparison of two-dimensional time of flight magnetic resonance angiography with cardiac compensated fast gradient recalled echo and contrast-enhanced three-dimensional time of flight magnetic resonance angiography.

We compared dynamic contrast-enhanced three-dimensional time of flight (3DTOF) magnetic resonance angiography (MRA) with two-dimensional time of flight (2DTOF) MRA with cardiac compensated fast gradient recalled echo (C-MON) and conventional angiography (CA) when it was available. C-MON re-orders the normal data acquisition to minimize ghosting artifacts generated by pulsatile flow. The initial phase of the study involved optimization of parameters and comparison C-MON with no C = MON in eight patients and volunteers. The final phase of the study involved 53 patients who were imaged with contrast-enhanced 3DTOF MRA and 2DTOF MRA with C-MON. Thirty of these patients also had CA. In the initial phase, 2DTOF MRA with C-MON was found to be equal (n = 3) or superior (n = 5) to 2DTOF without C-MON. In the final phase, the agreement among all imaging modalities varied from substantial to almost perfect (Cohen's kappa = .6-.83). The lowest agreement was using 2DTOF to evaluate the external iliac segments. The among suggested treatments varied from substantial to almost perfect for all imaging modalities (Cohen's kappa = .73-93). The diagnostic efficacies of 2DTOF with C-MON and contrast-enhanced 3DTOF were high overall, with the lowest value being a specificity of 63% for one reader in the evaluation of an external iliac segment using 2DTOF. In summary, 2DTOF with C-MON helped to eliminate artifacts due to pulsatility in the iliac arterial segments. In our experience, both dynamic contrast-enhanced 3DTOF MRA and 2DTOF MRA with C-MON performed well in the evaluation of the iliac arteries. Both studies have high interobeserver agreement and high diagnostic efficacy. Contrast-enhanced 3DTOF MRA should be reserved for situations in which the iliac vessels are extremely tortuous or occluded or the external iliac segments are poorly seen.

Local delivery of heparin with balloon angioplasty: results of a prospective randomized trial.

PURPOSE: To evaluate the effectiveness of local delivery of heparin via hydrogel-coated balloons in the treatment of vascular stenoses associated with hemodialysis access. MATERIALS AND METHODS: This was a randomized, prospective trial comparing treatment with hydrogel-coated balloon catheters delivered with heparin coating (n = 33) and without (n = 26). All patients were undergoing hemodialysis, and all stenoses involved the venous anastomosis of a dialysis graft or a native vein. The heparin-treated balloons were soaked in concentrated heparin and delivered in a protected manner to help prevent washout of heparin. RESULTS: The mean primary patencies were 143 days with heparin treatment and 214 days without heparin (P = .174). The mean assisted primary patencies were 165 days with heparin and 194 days without (P = .315). The mean secondary patencies were 351 days with heparin and 384 without (P = .81). CONCLUSION: In this population with this technique, the treatment outcome of venous outflow stenosis in patients with dialysis grafts is not improved with local delivery of heparin.

MR imaging of silicone breast implants: evaluation of prospective and retrospective interpretations and interobserver agreement.

MR imaging was used to evaluate the integrity of silicone breast implants in 54 women with 108 implants. MR images were interpreted by relatively inexperienced readers who tried to reproduce the experiences reported in the literature. The study examines the interobserver agreement using different diagnostic signs and the influence of experience on interpretation errors. Prospective and retrospective interpretations were compared with surgical findings at the time of explanation. Diagnostic indicators, including the linguine sign, the inverted tear drop sign, the C sign, water droplets mixed with silicone, and extracapsular globules of silicone, were evaluated for diagnostic efficacy and interobserver agreement. The prospective sensitivity and specificity were 87% and 78%, respectively. With the retrospective interpretations, the sensitivity and specificity increased to 93% and 92%, respectively. Most of the prospective false-positive interpretations were due to misinterpreting radial folds as signs of implant rupture. Six implants interpreted retrospectively as false positives had gross amounts of silicone around the implants at surgery but there were no obvious rents in the implant shells. There was fair to excellent interobserver agreement with the individual diagnostic signs except for extracapsular globules of silicone. All of the signs had specificities of greater than 90%. The sensitivities of the individual signs were less than the overall retrospective sensitivity. With experience, the sensitivity improved from 87% to 93% and the specificity improved from 78% to 92%. This study helps substantiate the use of diagnostic signs used by other authors to detect silicone loss from breast implants by MR imaging; however, questions remain as to the clinical role of MR imaging in evaluating implants for silicone loss.

Coronal fat suppression fast spin echo images of the knee: evaluation of 202 patients with arthroscopic correlation.

We optimized fat-suppressed fast spin echo (FS-FSE) parameters for coronal imaging of the knee and then evaluated the technique in a clinical setting. Five volunteers and 12 patients were used to evaluate various repetition (TR), echo (TE), and echo train lengths (ETL). Then, 202 patients underwent both knee MR imaging using coronal plane FS-FSE and arthroscopy. The coronal FS-FSE images were compared with radial multiplanar gradient-recalled echo (MPGRE), axial T1-weighted SE, and parasagittal double echo SE images. Proton density images (2,000/19) with an ETL of 2 best depicted the menisci, ligaments, and capsules. The conspicuity of osteochondral abnormalities depicted by the coronal FS-FSE imaging was significantly higher than for axial T1-weighted SE (p < .003) and parasagittal echo SE images (p < .003). The accuracy of the coronal FS-FSE imaging for medial and lateral meniscal tears was 91.6% and 87.6%, respectively. Combined imaging interpretation of the coronal FS-FSE, axial T1-weighted SE, and radial MPGRE imaging improved the accuracy for meniscal tears slightly over any sequence used alone, but the difference was not statistically significant. Fourteen capsular injuries were demonstrated by the coronal FS-FSE imaging. FS-FSE imaging in the coronal plane is a useful complementary sequence in MR examinations of the knee for the evaluation of meniscal tears, capsular injuries, and osteochondral abnormalities.

Percutaneous transluminal angioplasty versus endovascular stent placement in the treatment of venous stenoses in patients undergoing hemodialysis: intermediate results.

PURPOSE: This report describes intermediate findings from an ongoing prospective randomized trial comparing the results of percutaneous transluminal angioplasty (PTA) with results of endovascular stent placement in patients undergoing hemodialysis. PATIENTS AND METHODS: Among 87 consecutive patients with venous stenoses or occlusions, 47 (54%) were treated with PTA alone and 40 (46%) were treated with PTA and stent placement. RESULTS: For peripheral sites, the primary patency rates for PTA at 60, 180, and 360 days were 55%, 31%, and 10%, respectively, and for stents were 36%, 27%, and 11%, respectively (P = .6528). The secondary patency rates for PTA at 60, 180, and 360 days were 94%, 80%, and 71%, respectively, and for stents were 73%, 64%, and 64%, respectively (P = .1677). For central sites, the primary patency rates for PTA at 60, 180, and 360 days were 81%, 23%, and 12%, respectively, and for stents were 67%, 11%, and 11%, respectively (P = .4595). The secondary patency rates for PTA were 100% at each interval, and for stents were 100%, 89%, and 78%, respectively (P = .5408). CONCLUSION: Intermediate results suggest that, overall, there is no difference in the patency rates for peripheral venous stenoses in dialysis patients treated with PTA or PTA and endovascular stent placement. At this time, the numbers of patients are too small to conclude if certain sites such as larger central veins will respond better to one treatment or the other.

The role of percutaneous needle biopsies in the original diagnosis of lymphoma: a prospective evaluation.

PURPOSE: A prospective evaluation to determine if percutaneous needle biopsy yields enough tissue to establish the diagnosis of lymphoma and initiate therapy. PATIENTS AND METHODS: Lymphoma was diagnosed in 43 patients for the first time. Patients underwent either a core needle biopsy (n = 41) or an aspiration-type needle biopsy (n = 2) performed with imaging guidance. Immunochemical studies were performed on specimens from 39 of 43 patients (91%); flow cytometry was performed formed on specimens from 10 patients (23%). Patient progress was followed to see if biopsy results were used as a basis for treatment or if additional material was obtained with an open surgical procedure. RESULTS: On the basis of treatment decisions, needle biopsy results were sufficient for a diagnosis to be made in 36 of 43 patients (84%). In seven patients (16%), needle biopsy specimens were considered nondiagnostic, suspicious for lymphoma, or insufficient. None of the 43 patients responded to therapy in a manner that suggested the diagnosis of lymphoma to be incorrect. CONCLUSION: Image-guided needle biopsy should be the first procedure performed in the diagnosis of lymphoma, except in easily accessible superficial neck, inguinal, and axillary nodal sites.

Diagnosis of popliteus injuries with MR imaging.

OBJECTIVE: Popliteal muscle and tendon injuries are thought to be unusual. This report describes the magnetic resonance (MR) appearances of popliteus muscle and tendon injuries. DESIGN AND PATIENTS: The study included 24 patients where the diagnoses of popliteal injuries were prospectively made based on MR appearances. The study group was taken from 2412 consecutive knee MRIs. The injuries were characterized as to involving the muscular or tendinous portions of the popliteus apparatus. RESULTS: In 95.8% (23/24) of patients, the tears of the popliteus involved the muscular portion. The injuries were either partial and interstitial or complete. Three patients had tears of both the muscular and tendinous portions or the tendon alone. The anterior and posterior cruciate ligaments were torn in 16.7% (4/24) and 29.2% (7/24) of patients, respectively. There were medial and lateral meniscal tears in 45.8% (11/24) and 25% (6/24) of patients, respectively. There were injuries of the medial and lateral collateral ligaments in 8.3% (2/24) and 4.2% (1/24) of patients, respectively. Bone bruises and/or fractures were seen in 33.3% (8/24) patients. In 8.3% (2/24) of patients, the popliteus injury was an isolated finding. CONCLUSION: Popliteus muscle and tendon injuries are not uncommon. They usually occur in conjunction with other significant injuries of the knee and can be characterized with MR imaging.

Multicenter trial to evaluate vascular magnetic resonance angiography of the lower extremity. American College of Radiology Rapid Technology Assessment Group.

OBJECTIVES: To assess the value of magnetic resonance angiography (MRA) in presurgical evaluation of patients with severe lower limb atherosclerotic occlusive disease and to assess the feasibility of rapidly conducting rigorous technology assessment. DESIGN: Blinded, prospective study of consecutive patients with signs or symptoms of severe infrainguinal peripheral vascular disease who were candidates for percutaneous or surgical intervention. Using both descriptive statistics and multivariate logistic analyses, MRA was compared with contrast arteriography (CA) (the current technique) for imaging 15 arterial segments of the leg and foot. Intraoperative contrast angiography was the "gold" standard. Also studied was the effect of adding MRA to the information used in planning treatment. SETTING: Six US hospitals, one a community hospital. PATIENTS: A total of 155; 84% with either rest pain or tissue loss. RESULTS: Sensitivity in distinguishing patent segments from completely occluded segments was 83% for CA and 85% for MRA; both had 81% specificity. For distinguishing near-normal segments (suitable as bypass graft termini), CA was less sensitive than MRA (77% vs 82%), but more specific (92% vs 84%). After adjusting for same-reader effects, odds of correctly distinguishing patent segments were 1.6 times as great for MRA as for CA (P < .01); for distinguishing near-normal segments, the odds for CA were 1.5 times as great as for MRA (P < .05). The addition of MRA changed the treatment plan in 13% of patients; in 86% of these cases, the surgery actually performed indicated that the MRA-inclusive plan was superior. CONCLUSIONS: Individually, MRA and CA are approximately equivalent in diagnostic accuracy. The addition of MRA to treatment plans based only on CA and other diagnostic information clearly improves the plans. Completed in 15 months (as planned), our study demonstrates the feasibility of conducting rigorous technology assessment rapidly enough to be timely even in fields in which diagnostic and treatment techniques are rapidly changing.

Error patterns in the MR imaging evaluation of menisci of the knee.

PURPOSE: To categorize errors in interpretation of magnetic resonance (MR) images of the knee and explain the discrepancy between MR imaging and diagnostic arthroscopic findings. MATERIALS AND METHODS: Five hundred sixty-one patients underwent arthroscopy and MR imaging of the knee. Prospective and retrospective readings were used to categorize tear type and location. Sixty-six patients had 68 discrepancies between MR imaging and arthroscopic findings. RESULTS: Prospective interpretation of MR images of the lateral meniscus had a sensitivity of 82%, specificity of 98%, and accuracy of 93%. For images of the medial meniscus, sensitivity was 96%; specificity, 91%; and accuracy, 95%. The number of diagnostic errors at retrospective analysis was 76% (n = 52) of the number at prospective analysis. CONCLUSION: MR imaging is accurate in evaluation for meniscal tears. Most errors in interpretation that occur at prospective evaluation also occur at retrospective evaluation. Some false-positive errors may be related to incomplete arthroscopic evaluation of the meniscus and confusion between what represents fraying and what represents a tear.

Lower extremities: MR angiography with a unilateral telescopic phased-array coil.

In a comparison of conventional and magnetic resonance (MR) angiography of the lower extremities, MR imaging was performed with extremity and body coils and a unilateral six-coil telescopic phased-array coil. In one of seven volunteers, average signal-to-noise ratio was 140% higher with the latter (p < .01), only three of five stations were necessary, and examination time was decreased 50%. In the four patients, correlation in findings was 100%.