Correlation between magnetic resonance imaging of the heart and cardiac anatomy.

An understanding of anatomy forms the cornerstone for accurate interpretations of pathologic alterations. In this article, we present cardiac magnetic resonance images and the corresponding sections of normal hearts obtained at autopsy and cut in planes parallel and perpendicular to the ventricular septum in addition to the standard anatomic orthogonal planes (coronal, sagittal, and transverse). This correlation demonstrates the ability of magnetic resonance imaging to display cardiac anatomy accurately and noninvasively. Because magnetic resonance imaging provides excellent contrast between flowing blood and cardiac walls and has the capacity to provide direct images in multiple planes without inherent difficulties, this procedure has advantages over other currently available imaging techniques.

Evaluation of a new vascular occlusion device.

RATIONALE AND OBJECTIVES: A new vascular occlusion device was tested in canine femoral and iliac arteries and in an animal model of a patent ductus arteriosus (PDA). METHODS: Four variations of the vascular plug were placed into 18 iliac or femoral arteries of 17 mongrel dogs. Follow-up angiography was performed 1 hour and, if necessary, 2 hours after placement in all animals, 14 of which were then killed. Three dogs were followed angiographically for 2 weeks to 3 months. The "butterfly" plug was then tested in a canine model of a PDA. RESULTS: All plugs contained thrombi, and 12 of the 18 devices caused complete or nearly complete vascular occlusion within 2 hours. In one dog, one vascular plug had eroded through the vessel wall at 3 months without clinical sequelae. Successful PDA occlusion was achieved in 1 or 2 days in 6 of 8 dogs. Three misplacements occurred, one of which resulted in death. DISCUSSION: The balloon-expandable vascular plug appears to be a promising device for occlusion of blood vessels. Migration has not been observed once the device is placed, thus, sizing of the device appears less critical than with coils. However, modification of the delivery system and considerably more experience with the device are necessary to reduce the risk of misplacement.

Career advancement of men and women in academic radiology: is the playing field level?

RATIONALE AND OBJECTIVES: The authors' purposes were to determine if there are gender differences in the speed of promotion and/or academic productivity in academic radiology and if this situation had changed since a previous study was performed in 1987. MATERIALS AND METHODS: Surveys were distributed to faculty members of academic radiology departments in May 1997. A total of 707 surveys were analyzed according to gender for time at rank for assistant and associate professor levels, in relation to publication rate, grant funding rate, and distribution of professional time. RESULTS: There was no difference between genders in the time at assistant professor rank. Among all current professors, women had been associate professors longer than men, but there was no difference between genders for those who had been in academic radiology for less than 15 years. There was no gender difference at any rank in the rate of publishing original articles. There was no difference in funding rates, although men had more total grant support. Male associate professors reported spending more time in administration and slightly more time in total hours at work than did their female colleagues, and male professors spent slightly more time teaching residents. Otherwise, there is no difference in how men and women at any rank spend their professional time. There are, however, lower percentages of women in tenured positions and in the uppermost levels of departmental administration. CONCLUSION: The time at rank for men and women and their rate of publication appear to have equalized. Women still are underrepresented at the uppermost levels of departmental administration, however, and are less likely than men to hold tenured positions.

The road to success: factors affecting the speed of promotion of academic radiologists.

RATIONALE AND OBJECTIVES: The authors' purpose was to determine the factors influencing the speed of promotion of academic radiologists. MATERIALS AND METHODS: Three hundred forty-three surveys from faculty members of academic radiology departments with continuous academic careers were analyzed for time in rank at assistant and associate professor levels in relation to publication rate, grant funding rate, and distribution of professional time. Individuals promoted faster than the median time (6 years for assistant professors, 5 years for associate professors) were considered "fast track" and were compared with the remainder of the group. RESULTS: At the assistant professor level, fast track individuals had significantly higher rates of total publications and original articles than did others. At the level of associate professor, fast track individuals had significantly faster rates of publication of original articles, but no significant difference existed in total publication rate. No significant difference was found in the rate of founding of fast track individuals and others. Those with funding were not more likely to be on a fast track than those without funding. Fast track individuals spent significantly more time in administration at the assistant professor level than did other faculty, but no other significant differences were discovered in time distribution at the assistant or associate professor level. CONCLUSIONS: The rate of publishing original articles at the assistant and associate professor levels and the rate of overall publication at the assistant professor level were the most important parameters in predicting speed of promotion.

An improved system approach towards future cochlear implants.

Cochlear implants (CIs) have been used for many years to restore hearing for deaf patients. Unfortunately, today's CIs are still bulky devices and uncomfortable to wear. In this paper we present three innovations that ultimately should pave the way to a fully implantable bionic ear. First a microfabrication process used to fabricate the polymer metal microelectrode array for auditory nerve stimulation is discussed. Subsequently, a compact biphasic programmable stimulator chip to be used along with this electrode array is presented. By using a double loop feedback circuit topology, the circuit provides a precise stimulation current while requiring only little voltage headroom. The resulting low power consumption and reduced chip area allow for integration of the electronic circuitry onto the electrode array. Finally, as reliability and data transmission rate are two of the most critical issues in CI devices, we propose a software method to improve both data rate and reliability of transmitting digital data from the external part of the CI to the internal part with negligible power consumption.

Color Doppler sonography of the thoracic inlet veins.

Color duplex sonography of the thoracic inlet veins produces a spectrum of normal and abnormal findings. These vessels include the internal jugular, innominate, subclavian, and axillary veins. Although venography is the traditional means of imaging these veins, ultrasound lends itself to assessment of these vessels by providing anatomic and hemodynamic information. Advances in gray-scale resolution and color Doppler technology permit direct visualization of thrombus, stenosis, collateral vessels, catheters, and stents, as well as sensitive spectral waveform analysis. Abnormal findings in the thoracic inlet veins include locally elevated velocities at stenoses with low velocities peripherally. Thrombus, extrinsic compression, and collateral vessels may also produce abnormal findings. Common interpretive pitfalls are caused by transducer pressure, deep inspiration, slow flow, collateral veins, large-bore catheters, and hemodialysis fistulas. A thorough knowledge of the regional anatomy, normal and abnormal waveforms, and commonly encountered pitfalls will optimize the accuracy of color duplex sonography of the thoracic inlet veins.

Cranial lymphangiomatosis causing CSF otorrhea and recurrent meningitis: CT features.

We present a case of cranial lymphangiomatosis that resulted in CSF leakage through the ear and recurrent meningitis. The plain radiographic findings, CT, and CT cisternographic appearances are discussed along with a brief review of the literature.

Changes in tunneled catheter tip position when a patient is upright.

PURPOSE: To determine the relative changes in position of tunneled catheters from supine to upright patient position and factors affecting catheter tip migration. MATERIALS AND METHODS: One hundred forty-six different tunneled catheters were placed through the subclavian or jugular veins radiologically, and catheter positions were documented with use of cine radiography at the time of placement. Follow-up chest radiographs were obtained with the patient in the upright position within 48 hours after placement. Catheter tip positions were numbered from 1 to 8, with 1 representing the innominate/superior vena cava junction and 8, the lower right atrium. Patient sex and weight, the site of catheter entry, and the size and type of catheter were correlated with the relative change in position on the follow-up chest radiogrpahs. RESULTS: There was a statistically significant (P < .0001) change in catheter position on the follow-up chest radiographs, with a mean difference of 1.5 catheter positions (usually mid-right atrium initially to low superior vena cava on follow-up). Catheter tip migration was greater for catheters in the subclavian veins, in females, and in obese patients. CONCLUSIONS: The catheter tip migrates significantly from the initial position at the time of placement as compared to when the patient assumes the upright position. This knowledge is important in achieving the desired final catheter position.

Mechanical thrombectomy with the Amplatz device: human experience.

PURPOSE: The authors present their early experience of mechanical arterial and graft thrombectomy with the Amplatz thrombectomy device. PATIENTS AND METHODS: Preliminary data are presented for 14 patients treated with the Amplatz thrombectomy catheter. The procedure was carried out in 10 arterial polytetrafluorethylene grafts, in two native arteries, and in two patients with venous thrombosis. RESULTS: The thrombectomy catheter completely removed the clot in 11 patients and partially removed clot in three patients. Mean thrombectomy time was 2 minutes 45 seconds. Despite distal blood pressure cuff occlusion, two instances of insignificant distal embolization occurred. Mechanical clot dissolution has consistently produced hemolysis without adverse clinical effects. The underlying causative factors such as stenoses were treated by means of angioplasty, atherectomy, or surgical endarterectomy. CONCLUSION: Mechanical thrombectomy with this device is a new, effective technique and can rapidly remove the thrombus. From preliminary results, the device seems most promising in clearing out thrombi in occluded synthetic femoral-to-popliteal bypass grafts. The device could have wider application if it were steerable and if it could be introduced from the contralateral approach.

Renal duplex Doppler sonography in asymptomatic women during pregnancy.

The purpose of this study was to establish the normal range of the renal RI in pregnant women. Maternal renal RIs were calculated in 61 asymptomatic pregnant patients with at least unilateral pyelocaliectasis. A mean RI was calculated for each kidney. Overall, the mean RI was 0.61 +/- 0.05. The renal RI was > or = 0.70 in 4% (5/121) of kidneys with no statistically significant difference between the mean right (0.62 +/- 0.06) and left (0.60 +/- 0.04) kidney RIs. There was no correlation between trimester of pregnancy or degree of pyelocaliectasis and RI.

Iliofemoral venous stenoses: effectiveness of treatment with metallic endovascular stents.

PURPOSE: To assess effectiveness of metallic endovascular stents in treatment of venous stenoses and occlusions. MATERIALS AND METHODS: Stents were placed intravenously in 56 patients (59 stenoses or occlusions) over a 6-year period. Stent sites included the inferior vena cava (n = 10) and common iliac (n = 31), external iliac (n = 46), common femoral (n = 27), and superficial femoral veins (n = 4). Indications for stent placement included stenoses from pelvic malignancy and its treatment; trauma, surgery, or pregnancy; and idiopathic stenoses. Patients underwent anticoagulation therapy for 3-6 months after stent placement. Follow-up was performed with duplex ultrasound. RESULTS: With use of life-table analysis, overall primary and secondary 1-year patency rates were 50% and 81%, respectively. Primary and secondary 4-year patency rates were and 50% and 75%, respectively. Five patients died of primary disease progression within 6 months after stent placement. Major complications occurred in 6.8% of cases. One-year secondary patency rates were statistically significantly lower (P = .05) for patients with malignant disease, although primary patency rates were comparable. Overall sustained decrease in symptoms (P < .0001) was observed 1 year later. CONCLUSION: Endovascular stent placement is a nonsurgical alternative for reestablishment of venous flow and sustained relief of symptoms in patients with malignant or benign pelvic venous disease.

Mechanical thrombectomy: results of early experience.

PURPOSE: To evaluate the clinical application of a mechanical thrombectomy device in occluded lower extremity arteries and bypass grafts. MATERIALS AND METHODS: A mechanical thrombectomy device was used in five patients with acutely occluded lower extremity bypass grafts (n = 2) or superficial femoral arteries (n = 3). RESULTS: The thrombus was completely removed in three cases (two bypass grafts and one native superficial femoral artery). In two of the patients with occlusions in the native superficial femoral artery, the thrombus was partially removed. In these two patients, the aspirate demonstrated a more fibrous thrombus that was not easily fragmented. In one of these two patients, the coagulum was thought to be embolic from the heart. CONCLUSION: The thrombectomy device works well in recent thromboses, particularly in polytetrafluoroethylene grafts in which organization does not occur. Its efficacy in chronically occluded vessels is not certain.

Duplex sonography after transjugular intrahepatic portosystemic shunts (TIPS): normal hemodynamic findings and efficacy in predicting shunt patency and stenosis.

OBJECTIVE: Portal hemodynamics are altered by placement of a transjugular intrahepatic portosystemic shunt (TIPS). Normal duplex sonographic findings after TIPS placement and hemodynamic alterations indicating shunt failure have not yet been well described. The purposes of this study were to determine normal hemodynamic changes on duplex sonography after TIPS placement and to assess the efficacy of duplex sonography in detecting shunt dysfunction. SUBJECTS AND METHODS: Forty patients underwent TIPS placement and were entered into a study that included routine sonographic evaluation and portal venography at regular intervals. Portal venography was also performed if shunt velocities on duplex sonography changed from the baseline, which raised the question of shunt stenosis or occlusion. The pre-TIPS duplex sonographic study included determination of patency, velocity, and flow direction in the main, right, and left portal veins and in the hepatic artery. Follow-up sonography included the pre-TIPS examination in addition to velocity determinations in three segments of the shunt. Correlation was made between 82 concurrent sonographic and portal venographic studies. RESULTS: High-velocity blood flow (mean peak velocity, 135-200 cm/sec) was consistently seen within patent, well-functioning shunts. Hepatic artery peak systolic velocities increased from 79 cm/sec before TIPS placement to 131 cm/sec after TIPS placement (p < .001). Main portal vein velocities increased from 21.8 cm/sec before TIPS placement to 41.5 cm/sec after TIPS placement (p < .001). When compared with portal venography, duplex sonography was 98% sensitive and 100% specific in predicting the presence of blood flow within the stent. Sonography was highly sensitive and specific for detecting stent stenosis. Final sonographic criteria for shunt stenosis in angiographically documented cases were low-velocity shunt flow (< or = 60 cm/sec) in the entire stent, or low-velocity shunt flow with an associated focal velocity elevation. CONCLUSION: Consistent changes in portal venous and hepatic arterial hemodynamics are normally seen on duplex sonography after placement of a TIPS. Duplex sonography accurately predicts shunt patency and dysfunction when compared with portal venography. Duplex sonography is an effective, noninvasive method of evaluating shunt function and should be considered for use as the primary imaging technique in routine follow-up after TIPS placement.

Applications of the Amplatz snare device during interventional radiologic procedures.

The Amplatz gooseneck snare (Microvena, St. Paul, MN) is a recently developed device for the percutaneous removal of intravascular foreign bodies [1-5] (Fig. 1). In the past several years, various other applications of this snare system have been devised for placing, replacing, repositioning, or removing guidewires, catheters, and other devices during interventional procedures. The Amplatz gooseneck snare, which has been described [1], comes in a variety of loop sizes and is provided with either 4- or 6-French guiding catheters, although substitution with any of several soft, blunt-tipped guiding catheters is possible [5]. The principal advantage of the Amplatz snare over past systems is that the loop is at a right angle to the catheter, easing the capture of foreign bodies, devices, or catheters.

In vitro and in vivo experimental evaluation of a new vena caval filter.

PURPOSE: A new stainless steel (MP35N alloy) vena cava filter without a central stasis point was evaluated in vitro and in vivo. MATERIALS AND METHODS: The clot-trapping efficiency and hemodynamic flow pattern of the filter were assessed in a flow model and were compared with those of currently available commercial filters including the Vena Tech-LGM, Simon nitinol, Greenfield, and Bird's Nest filters. The new filter was placed in the inferior vena cava (IVC) of 31 dogs; 21 of the 31 dogs were followed up with cavography for up to 3 months. At the termination of the study, the filters and IVCs were examined grossly and histologically. An in vivo clot-trapping test was carried out in five dogs. RESULTS: The least turbulence was noted with the new filter and the titanium Greenfield filter. The stainless steel Greenfield and Simon nitinol filters caused major flow disturbances. Migration within 5 cm of initial placement occurred in two animals (9.5%). There were no IVC thromboses, perforations, or filter embolizations. An in vivo clot-trapping study showed an 80% efficiency for small thrombi (3 x 20 mm) and 100% efficiency for large thrombi (6 x 20 mm) with the new filter. The Simon and the new filter had the best clot-trapping capabilities. The Vena Tech-LGM and Bird's Nest filters were slightly inferior and the Greenfield filter demonstrated by far the lowest trapping capacity. CONCLUSION: The new vena cava filter is easily introduced percutaneously through a 12-F sheath and appears to be very promising due to its high filtering capability, low turbulence, nonmagnetic properties, good mechanical stability, and hypothrombogenicity. Clinical trials are warranted.

The mechanisms of positional dysfunction of subclavian venous catheters.

PURPOSE: To determine the origin of subclavian vein catheter and lead dysfunction. MATERIALS AND METHODS: Cineradiography was performed on 10 patients with subclavian venous catheter dysfunction and three patients with pacemaker or defibrillator lead dysfunction. The leads and catheters were removed and replaced with use of a fluoroscopically guided technique; the needle entered the vein lateral to the first rib. Repeat cine examinations were performed following placement of new catheters. RESULTS: The cause of the dysfunction of all 10 catheters was shown to be pinch by the subclavicular musculotendinous tissues as the catheter passed below the clavicle toward its entry into the vein. All three leads were entrapped in the subclavicular tissues and stretched during abduction. The abnormal motion and clinical problems were eliminated after replacement. CONCLUSION: Subclavian catheter and lead malfunction is not due to compression between the first rib and the clavicle. It is due to entrapment in the subclavius muscle-costoclavicular ligament complex, which binds or compresses the device during movements. These problems can be avoided by employing fluoroscopically guided puncture techniques that enter the vein lateral to the first rib.

Recirculation-type Amplatz clot macerator: determination of particle size and distribution.

PURPOSE: A high-speed mechanical clot macerator was tested in vitro, and the distributions and sizes of residual particles produced by this device were determined. MATERIALS AND METHODS: Human thrombi aged for 4 days and 10 days were macerated using a recirculation-type Amplatz thrombectomy device with an 8-F, high-speed screw propeller. The device was activated for 15, 30, and 60 seconds. Two different methods of particle measurement were used to determine overall particle distribution and to determine the size and number of large particles. RESULTS: The recirculation device liquefied 99.2% of 4-day-old and 98.8% of 10-day-old thrombi, producing particles ranging in size from 13 to 1,000 microns; all particles were smaller than 1,000 microns. Particle size and distribution results were identical for the 30-second and 60-second activation times. CONCLUSION: The recirculation-type thrombectomy device appears to perform well as a method of macerating human thrombi. Clinical trials need to be conducted to test the device further and to determine if it can be used safely on venous as well as arterial occlusions.

Effect of transjugular intrahepatic portosystemic shunt on quality of life.

OBJECTIVE: The objective of this study was to determine the effect of the transjugular intrahepatic portosystemic shunt (TIPS) procedure on the quality of life. SUBJECTS AND METHODS: Data were collected on 99 patients who underwent the TIPS procedure between September 1991 and September 1995. Quality of life was assessed by the Karnofsky scale before and at intervals after the procedure. Procedure-related complications and other aspects of the patients' overall well-being, as reflected in liver and kidney function and nutritional status, were reviewed immediately before and after TIPS creation. Finally, mortality and TIPS patency rates were tabulated. RESULTS: We observed significantly improved quality of life. The quality of life remained significantly improved throughout the 24-month follow-up period. During the 1- to 3-month interval after the TIPS procedure, we observed in patients a significant decrease in blood urea nitrogen and an increase in albumin and bilirubin. During this period, patients had no significant change in liver enzymes, prothrombin time, ammonia, or creatinine. Complications of the TIPS procedure included a 30% incidence of new or worsened encephalopathy and a 15% incidence of other severe complications (intraperitoneal hemorrhage, severe accelerated liver failure). The procedure-related death rate was 5%. Longer term follow-up showed an overall sustained decrease in blood urea nitrogen, an increase in albumin, and a return of bilirubin to the pre-TIPS levels or below. CONCLUSION: For patients who survive longer than 1 month, TIPS results in an overall, sustained improvement in the quality of life. Improved quality of life may result from a low incidence of repeat variceal bleeding, decreased ascites, and improved nutritional status.

Hemolytic effect of the Amplatz thrombectomy device.

PURPOSE: The hemolytic effect of the Amplatz thrombectomy device (ATD) was evaluated in nine dogs and in nine patients. MATERIALS AND METHODS: The device was activated for 1-2 minutes in the abdominal aorta, inferior vena cava, or femoral artery of nine dogs. The device was activated for 1-4 minutes in the nine patients in occluded lower extremity bypass grafts (n = 5), native superficial femoral artery (n = 1), a pulmonary artery embolus (n = 1), a portocaval shunt (n = 1), and an iliac vein stent (n = 1). Patients were examined for laboratory evidence of hemolysis following mechanical thrombectomy. RESULTS: In all dogs haptoglobin level decreased, free hemoglobin level in the plasma increased, and hemoglobinuria was present. There was no change in renal function. The level of haptoglobin decreased and the level of plasma free hemoglobin increased in eight patients, with hemoglobinuria detected in one. More hemolysis was observed in the animals than in the patients. CONCLUSION: The ATD has a definite transient hemolytic effect. Until further studied, it should not be used in children and should be used with caution in patients who are anemic, hypoxemic, or have potentially reversible renal insufficiency. Activation time should be monitored closely because hemolysis probably increases with increasing activation time.