Priscilla Winchester | Columbia University Medical Center (original) (raw)

Papers by Priscilla Winchester

Applied Radiology, 2002

... Meaney, MD; K. Craig Kent, MD; Peter L. Choyke, MD; Richard Watts, PhD; Maureen N. Hood, BSN;... more ... Meaney, MD; K. Craig Kent, MD; Peter L. Choyke, MD; Richard Watts, PhD; Maureen N. Hood, BSN; Yi Wang, PhD; Priscilla Winchester, MD ... peripheral vascular disease, it is essential to image an extensive region of arterial anatomy from the abdominal aorta down to the feet. ...

Radiology, 2000

A view order that matches k-space sampling to cardiac motion within the acquisition window was de... more A view order that matches k-space sampling to cardiac motion within the acquisition window was developed for breath-hold three-dimensional contrast material-enhanced coronary magnetic resonance angiography. In vivo experiments in seven volunteers demonstrated that blurring was substantially reduced with this motion-matched view order as compared with the standard centric view order. Coronary arteries were well delineated.

The American Journal of Sports Medicine, 2007

... Connett MC, Murray DH Jr, Wenneker WW. Peripheral arterial emboli. Am J Surg. 1984;148:14–19.... more ... Connett MC, Murray DH Jr, Wenneker WW. Peripheral arterial emboli. Am J Surg. 1984;148:14–19. ...

Radiology, Aug 1, 1977

Capillary hemangiomas of the lung are very rare, usually presenting solitary circumscribed lesion... more Capillary hemangiomas of the lung are very rare, usually presenting solitary circumscribed lesions on chest radiographs. Hemoptysis is frequently present. All 7 known patients with isolated pulmonary capillary hemangiomas have been females. The authors describe a girl followed up from 2 months to 3 1/2 years of age with a large lesion which at times appeared as a mass of water density and at other times as air-filled cysts. This changing radiological pattern correlated well with the pathological evidence of repeated hemorrhage, scarring, air trapping, and cyst formation.

PURPOSE/AIM Identify pertinent findings and generate differential diagnosis for given cardiac cas... more PURPOSE/AIM Identify pertinent findings and generate differential diagnosis for given cardiac case of the day.

Radiology, 2002

The purpose of this study was to improve dynamic two-dimensional projection magnetic resonance di... more The purpose of this study was to improve dynamic two-dimensional projection magnetic resonance digital subtraction angiography by using remasking and filtering postprocessing techniques. Four methods were evaluated in 50 patients: default mask subtraction, remasked subtraction, filtering based on the SD, and linear filtering. The results demonstrated that postprocessing techniques such as linear filtering can reduce background motion artifacts and improve arterial contrast-to-noise ratio.

Radiology, 2002

To compare combined three-dimensional (3D) and two-dimensional (2D) contrast material-enhanced ma... more To compare combined three-dimensional (3D) and two-dimensional (2D) contrast material-enhanced magnetic resonance (MR) angiography with x-ray angiography for planning treatment of peripheral vascular disease. Three radiologists retrospectively reviewed the pretreatment x-ray angiographic and MR angiographic studies obtained in 30 consecutive patients: 15 patients (15 limbs) evaluated for limb salvage and 15 patients (20 limbs) evaluated because of claudication. MR angiography included acquisition of 2D contrast-enhanced MR digital subtraction angiograms of the area from the adductor canal to the feet and 3D spoiled gradient-recalled-echo bolus chase MR angiograms obtained in three stations from the aorta to the middle portion of the calf. Each reader reviewed the x-ray and MR angiograms to determine the inflow and outflow segments for a hypothetical bypass graft placement. The three readers selected identical segments for inflow at MR angiography and x-ray angiography in 32, 32, and 35 of the 35 limbs evaluated (mean percentages of agreement [95% CI ]: 91% [77%, 98%], 91% [77%, 98%], and 95% [90%, 100%], respectively). The readers selected identical segments for outflow in 32, 32, and 34 of the 35 limbs evaluated (mean percentages of agreement [95% CI]: 91% [77%, 98%], 91% [77%, 98%], and 97% [85%, 100%], respectively). Preliminary data support the combining of 2D MR digital subtraction angiography with 3D bolus chase MR angiography to extend the utility of 3D MR angiography in treatment planning to include patients being evaluated for limb salvage, as well as those being evaluated for claudication.

Radiology, 2002

To retrospectively review time-resolved two-dimensional projection magnetic resonance (MR) angiog... more To retrospectively review time-resolved two-dimensional projection magnetic resonance (MR) angiographic data to characterize the passage of gadolinium-based contrast material down the leg arteries in patients undergoing peripheral MR angiography. Data of 87 consecutive standardized peripheral MR angiographic examinations were retrospectively reviewed to determine contrast material arrival times to the common femoral artery (CFA), the popliteal and tibial arteries, and the corresponding veins. Travel times were correlated with clinical data obtained with retrospective chart review and predictive multiparameter models developed with stepwise linear regression. The mean travel time of contrast material to the CFA was 24 seconds +/- 6 (SD), with additional 5 seconds +/- 2 to reach the popliteal artery and 7 seconds +/- 4 to reach the ankle artery. The mean time window of arterial enhancement was 49 seconds +/- 10 in the pelvis, 45 seconds +/- 10 in the thigh, and 35 seconds +/- 14 in the calf. The travel time to CFA was correlated with aortic aneurysm (r = 0.41; P <.001), increasing age (r = 0.31; P =.003), male sex (r = 0.3; P =.005), myocardial infarction (r = 0.26; P =.016), and type 2 diabetes mellitus (r = -0.22; P =.041). Predicted travel time to CFA was 10.6 seconds, plus 0.143 seconds times patient age, plus 4.8 seconds if aneurysm was present, plus 3.8 seconds if male sex, plus 2.8 seconds if history of myocardial infarction. Contrast material injected intravenously traveled rapidly down the peripheral arteries at approximately 6 seconds per station, but a long arterial phase time window allowed bolus-chase peripheral MR angiography to function with slower table stepping. Patient-to-patient variations in contrast material kinetics may be anticipated on the basis of age, sex, and clinical parameters.

Radiology, 2001

The purpose of this study was to evaluate a variable k-space sampling method for bolus-chase thre... more The purpose of this study was to evaluate a variable k-space sampling method for bolus-chase three-dimensional magnetic resonance digital subtraction angiography in the arterial system from the abdomen to the calf. Imaging time was minimized by tailoring the acquisition according to the vascular anatomy of the station. For images obtained in 30 patients, results with the modified protocol were compared to those with the previously published protocol. For all stations, significant improvement (P <.001) was found with the modified protocol.

Magnetic Resonance in Medicine, 1998

To acquire multiple longitudinal locations in the lower extremity after a single contrast injecti... more To acquire multiple longitudinal locations in the lower extremity after a single contrast injection, appropriate table translation and contrast injection are required. An approximate model based on constant bolus velocity was developed to describe the space-time course of a contrast bolus in the lower extremity. This model was verified in dynamic MR angiograms acquired in a group of patients using time-resolved 2D MR digital subtraction angiography (MRDSA). From this contrast bolus passage model, a timing algorithm for table translation and contrast injection was developed for bolus chase MRDSA, subsequently validated in bolus chase 2D MRDSA experiments. All targeted major peripheral arteries were well depicted in bolus chase 2D MRDSA using this timing algorithm and a single 15-ml contrast dose.

Magnetic Resonance in Medicine, 2002

Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the ac... more Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional ellipticalcentric view-ordering because the critical k-space center must be acquired with full arterial enhancement. In this study, a recessed elliptical-centric view-ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view-ordering is shown to be more robust to timing errors than the conventional scheme in a study of 37 patients. Magn Reson Med 48:419 -424, 2002.

Journal of Vascular Surgery, 2001

Journal of Vascular and Interventional Radiology, 1998

To compare the rates of thrombolysis produced by forced intrathrombic injections of saline versus... more To compare the rates of thrombolysis produced by forced intrathrombic injections of saline versus urokinase, as well as automated versus manual injections of urokinase, with use of an in vitro model of a vascular occlusion. The rates of thrombolysis produced by forced intrathrombic injections of saline and urokinase were compared in an in vitro radiometric model utilizing I-125-labeled thrombus. Similar experiments were performed to compare manual and automated injections of urokinase. The dissolution of the thrombus was quantitatively monitored with use of a scintillation detector. Averaged time activity data for each type of experiment were fit to exponential functions and half times of lysis calculated. The differences in the half times for the experiments being compared were evaluated for significance with use of the Student t test. The half times of lysis produced by forced intrathrombic injections of urokinase were substantially and significantly shorter than those produced by forced saline injections. The half time of lysis produced by automated injections was not significantly different than that produced by manual injections. Forced intrathrombic injections of urokinase produce faster and substantially more thrombolysis when compared with similarly administered saline. Also, for forced intrathrombic injections of lytic agents, an automated injector is an equivalent alternative to manual injections.

Journal of Vascular and Interventional Radiology, 1996

« PreviousNext »Journal of Vascular and Interventional Radiology Volume 7, Issue 6 , Pages 813-81... more « PreviousNext »Journal of Vascular and Interventional Radiology Volume 7, Issue 6 , Pages 813-817, November 1996. Embolization of Backbleeding Lumbar Arteries Filling an Aortic Aneurysm Sac after Endovascular Stent-Graft Placement☆. Neil M. Khilnani, MD: Affiliations. ...

Journal of Vascular and Interventional Radiology, 1998

To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensio... more To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA). Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found. Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively. Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.

Journal of Magnetic Resonance Imaging, 2004

To evaluate visualization inside platinum stents with three-dimensional contrast-enhanced magneti... more To evaluate visualization inside platinum stents with three-dimensional contrast-enhanced magnetic resonance angiography (CE-MRA). Breath-hold three-dimensional gadolinium (Gd) MRA was performed on 18 patients with 22 platinum stents in the renal (n = 18), celiac (n = 1), superior mesenteric (n = 1), and iliac (n = 2) arteries. Electronic calibers were used to measure the lumen diameter within the stent and just distal to the stent to calculate percent stenosis. MRA accuracy was determined from the difference between percent stenosis measured on MRA and digital subtracted angiography (DSA). The patients were imaged at flip angles of 45 degrees , 60 degrees , 75 degrees , 90 degrees , and 150 degrees . MRA demonstrated the stent lumen in all of the patients, with a mean difference between MRA and DSA of 21%. For stents oriented parallel to B0 (iliac arteries) the difference was only 10%, as compared to 22% for stents perpendicular to B0. The flip angle with the best agreement between MRA and DSA was 75 degrees (16%). The lumen of a platinum stent can be imaged with three-dimensional CE-MRA, although grading of restenosis has limited accuracy. The best results were obtained with a flip angle of 75 degrees and for stents in the iliac arteries parallel to B0.

Journal of Magnetic Resonance Imaging, 2004

To evaluate the incidence and locations of soft tissue enhancement on time-resolved two-dimension... more To evaluate the incidence and locations of soft tissue enhancement on time-resolved two-dimensional projection magnetic resonance angiography (MRA) of the calf and foot. Time-resolved two-dimensional projection MRA of the knee, calf, and foot, performed at 1.5 Tesla using the head coil, was retrospectively reviewed in 326 patients. Soft tissue enhancement of the foot was identified and graded by blinded review. Subsequently, patient medical records were reviewed to determine the presence or absence of diabetes, cellulitis, gangrene, and ulceration of the foot and presence of neuropathic joints. Enhancing spots were identified in 228 patients. For those feet without clinical abnormalities, diabetic patients had an average of 1.2 enhancing spots per foot, while nondiabetics had only 0.6 (P < 0.001). Higher-grade lesions were more prevalent in diabetics and in heavier patients. Of 64 patients with follow-up, 8 (13%) developed cellulitis (N = 4) or ulceration (N = 4) at the location of an enhancing spot, including 5 diabetic and 3 nondiabetic patients. Pedal soft tissue enhancement frequently occurs on time-resolved gadolinium (Gd):MRA of the feet. The etiology is uncertain, but the high frequency in diabetic patients and observation of progression to cellulitis/ulceration suggest this soft tissue enhancement may identify sites of subclinical pedal soft tissue injury.

Investigative Radiology, 2002

To investigate the phenomena and causes for undesired venous signal in the distal station of bolu... more To investigate the phenomena and causes for undesired venous signal in the distal station of bolus chase 3D MRA. Consecutive patients (in 8 months) undergoing peripheral MRA consisting of 2D projection MRA of the tibial trifurcation and 3D bolus chase MRA were retrospectively evaluated. Venous contamination in mid-calf in bolus chase 3D MRA was correlated to the arterial phase duration, the time between the contrast bolus arrival and venous return measured on time resolved 2D images. Statistical analyses were performed to identify the clinical parameters indicative of venous contamination. The arterial phase durations at the mid-calf were 49 +/- 8 seconds on 101 legs without venous signal in the bolus chase 3D MRA, 35 +/- 9 seconds on 13 legs with moderate venous signal, and 20 +/- 4 seconds on 40 legs with substantial venous signal; the differences were significant among different venous signal levels (P < 0.001 for all pairs). Legs with cellulitis had shorter arterial phase and more venous contamination than legs without cellulitis (P < 0.05). Patients with myocardial infarction had longer arterial phase and less venous contamination than patients without myocardial infarction (P < 0.01). Venous signal in the distal calf station of bolus chase 3D peripheral MRA is caused by fast arterial-venous transit. It is worse in legs with cellulitis and less in patients with a history of myocardial infarction.

Investigative Radiology, 2001

The purpose of this study was to identify the cross-sectional location of collateral vessels in p... more The purpose of this study was to identify the cross-sectional location of collateral vessels in patients with peripheral vascular disease on three-dimensional magnetic resonance angiograms (3D MRAs) to suggest sites for intravascular or transcutaneous angiogenesis gene delivery in the lower extremity. The axial locations were measured and categorized by tissue compartments, as well as by radial coordinates with respect to the femur. Collateral vessels in the thigh were identified in 24 of 93 consecutive patients who underwent peripheral 3D MRA. Ninety-one percent (99/109) of the observed collaterals were located near the adductor canal level of the thigh, with 78% (31/46) of these collaterals located in the fat in or surrounding the posterior muscle. The majority of collateral vessels in the thigh are located in the fat or muscle within the posterior compartment near the femur at the level of the adductor canal.

Investigative Radiology, 2001

Wang Y, Winchester PA, Khilnani NM, et al. Contrast-en-hanced peripheral MR angiography from the ... more Wang Y, Winchester PA, Khilnani NM, et al. Contrast-en-hanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170 –177. ...

Applied Radiology, 2002

... Meaney, MD; K. Craig Kent, MD; Peter L. Choyke, MD; Richard Watts, PhD; Maureen N. Hood, BSN;... more ... Meaney, MD; K. Craig Kent, MD; Peter L. Choyke, MD; Richard Watts, PhD; Maureen N. Hood, BSN; Yi Wang, PhD; Priscilla Winchester, MD ... peripheral vascular disease, it is essential to image an extensive region of arterial anatomy from the abdominal aorta down to the feet. ...

Radiology, 2000

A view order that matches k-space sampling to cardiac motion within the acquisition window was de... more A view order that matches k-space sampling to cardiac motion within the acquisition window was developed for breath-hold three-dimensional contrast material-enhanced coronary magnetic resonance angiography. In vivo experiments in seven volunteers demonstrated that blurring was substantially reduced with this motion-matched view order as compared with the standard centric view order. Coronary arteries were well delineated.

The American Journal of Sports Medicine, 2007

... Connett MC, Murray DH Jr, Wenneker WW. Peripheral arterial emboli. Am J Surg. 1984;148:14–19.... more ... Connett MC, Murray DH Jr, Wenneker WW. Peripheral arterial emboli. Am J Surg. 1984;148:14–19. ...

Radiology, Aug 1, 1977

Capillary hemangiomas of the lung are very rare, usually presenting solitary circumscribed lesion... more Capillary hemangiomas of the lung are very rare, usually presenting solitary circumscribed lesions on chest radiographs. Hemoptysis is frequently present. All 7 known patients with isolated pulmonary capillary hemangiomas have been females. The authors describe a girl followed up from 2 months to 3 1/2 years of age with a large lesion which at times appeared as a mass of water density and at other times as air-filled cysts. This changing radiological pattern correlated well with the pathological evidence of repeated hemorrhage, scarring, air trapping, and cyst formation.

PURPOSE/AIM Identify pertinent findings and generate differential diagnosis for given cardiac cas... more PURPOSE/AIM Identify pertinent findings and generate differential diagnosis for given cardiac case of the day.

Radiology, 2002

The purpose of this study was to improve dynamic two-dimensional projection magnetic resonance di... more The purpose of this study was to improve dynamic two-dimensional projection magnetic resonance digital subtraction angiography by using remasking and filtering postprocessing techniques. Four methods were evaluated in 50 patients: default mask subtraction, remasked subtraction, filtering based on the SD, and linear filtering. The results demonstrated that postprocessing techniques such as linear filtering can reduce background motion artifacts and improve arterial contrast-to-noise ratio.

Radiology, 2002

To compare combined three-dimensional (3D) and two-dimensional (2D) contrast material-enhanced ma... more To compare combined three-dimensional (3D) and two-dimensional (2D) contrast material-enhanced magnetic resonance (MR) angiography with x-ray angiography for planning treatment of peripheral vascular disease. Three radiologists retrospectively reviewed the pretreatment x-ray angiographic and MR angiographic studies obtained in 30 consecutive patients: 15 patients (15 limbs) evaluated for limb salvage and 15 patients (20 limbs) evaluated because of claudication. MR angiography included acquisition of 2D contrast-enhanced MR digital subtraction angiograms of the area from the adductor canal to the feet and 3D spoiled gradient-recalled-echo bolus chase MR angiograms obtained in three stations from the aorta to the middle portion of the calf. Each reader reviewed the x-ray and MR angiograms to determine the inflow and outflow segments for a hypothetical bypass graft placement. The three readers selected identical segments for inflow at MR angiography and x-ray angiography in 32, 32, and 35 of the 35 limbs evaluated (mean percentages of agreement [95% CI ]: 91% [77%, 98%], 91% [77%, 98%], and 95% [90%, 100%], respectively). The readers selected identical segments for outflow in 32, 32, and 34 of the 35 limbs evaluated (mean percentages of agreement [95% CI]: 91% [77%, 98%], 91% [77%, 98%], and 97% [85%, 100%], respectively). Preliminary data support the combining of 2D MR digital subtraction angiography with 3D bolus chase MR angiography to extend the utility of 3D MR angiography in treatment planning to include patients being evaluated for limb salvage, as well as those being evaluated for claudication.

Radiology, 2002

To retrospectively review time-resolved two-dimensional projection magnetic resonance (MR) angiog... more To retrospectively review time-resolved two-dimensional projection magnetic resonance (MR) angiographic data to characterize the passage of gadolinium-based contrast material down the leg arteries in patients undergoing peripheral MR angiography. Data of 87 consecutive standardized peripheral MR angiographic examinations were retrospectively reviewed to determine contrast material arrival times to the common femoral artery (CFA), the popliteal and tibial arteries, and the corresponding veins. Travel times were correlated with clinical data obtained with retrospective chart review and predictive multiparameter models developed with stepwise linear regression. The mean travel time of contrast material to the CFA was 24 seconds +/- 6 (SD), with additional 5 seconds +/- 2 to reach the popliteal artery and 7 seconds +/- 4 to reach the ankle artery. The mean time window of arterial enhancement was 49 seconds +/- 10 in the pelvis, 45 seconds +/- 10 in the thigh, and 35 seconds +/- 14 in the calf. The travel time to CFA was correlated with aortic aneurysm (r = 0.41; P <.001), increasing age (r = 0.31; P =.003), male sex (r = 0.3; P =.005), myocardial infarction (r = 0.26; P =.016), and type 2 diabetes mellitus (r = -0.22; P =.041). Predicted travel time to CFA was 10.6 seconds, plus 0.143 seconds times patient age, plus 4.8 seconds if aneurysm was present, plus 3.8 seconds if male sex, plus 2.8 seconds if history of myocardial infarction. Contrast material injected intravenously traveled rapidly down the peripheral arteries at approximately 6 seconds per station, but a long arterial phase time window allowed bolus-chase peripheral MR angiography to function with slower table stepping. Patient-to-patient variations in contrast material kinetics may be anticipated on the basis of age, sex, and clinical parameters.

Radiology, 2001

The purpose of this study was to evaluate a variable k-space sampling method for bolus-chase thre... more The purpose of this study was to evaluate a variable k-space sampling method for bolus-chase three-dimensional magnetic resonance digital subtraction angiography in the arterial system from the abdomen to the calf. Imaging time was minimized by tailoring the acquisition according to the vascular anatomy of the station. For images obtained in 30 patients, results with the modified protocol were compared to those with the previously published protocol. For all stations, significant improvement (P <.001) was found with the modified protocol.

Magnetic Resonance in Medicine, 1998

To acquire multiple longitudinal locations in the lower extremity after a single contrast injecti... more To acquire multiple longitudinal locations in the lower extremity after a single contrast injection, appropriate table translation and contrast injection are required. An approximate model based on constant bolus velocity was developed to describe the space-time course of a contrast bolus in the lower extremity. This model was verified in dynamic MR angiograms acquired in a group of patients using time-resolved 2D MR digital subtraction angiography (MRDSA). From this contrast bolus passage model, a timing algorithm for table translation and contrast injection was developed for bolus chase MRDSA, subsequently validated in bolus chase 2D MRDSA experiments. All targeted major peripheral arteries were well depicted in bolus chase 2D MRDSA using this timing algorithm and a single 15-ml contrast dose.

Magnetic Resonance in Medicine, 2002

Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the ac... more Fast arterial-venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional ellipticalcentric view-ordering because the critical k-space center must be acquired with full arterial enhancement. In this study, a recessed elliptical-centric view-ordering scheme is introduced in which the k-space center is acquired a few seconds following scan initiation. The recessed view-ordering is shown to be more robust to timing errors than the conventional scheme in a study of 37 patients. Magn Reson Med 48:419 -424, 2002.

Journal of Vascular Surgery, 2001

Journal of Vascular and Interventional Radiology, 1998

To compare the rates of thrombolysis produced by forced intrathrombic injections of saline versus... more To compare the rates of thrombolysis produced by forced intrathrombic injections of saline versus urokinase, as well as automated versus manual injections of urokinase, with use of an in vitro model of a vascular occlusion. The rates of thrombolysis produced by forced intrathrombic injections of saline and urokinase were compared in an in vitro radiometric model utilizing I-125-labeled thrombus. Similar experiments were performed to compare manual and automated injections of urokinase. The dissolution of the thrombus was quantitatively monitored with use of a scintillation detector. Averaged time activity data for each type of experiment were fit to exponential functions and half times of lysis calculated. The differences in the half times for the experiments being compared were evaluated for significance with use of the Student t test. The half times of lysis produced by forced intrathrombic injections of urokinase were substantially and significantly shorter than those produced by forced saline injections. The half time of lysis produced by automated injections was not significantly different than that produced by manual injections. Forced intrathrombic injections of urokinase produce faster and substantially more thrombolysis when compared with similarly administered saline. Also, for forced intrathrombic injections of lytic agents, an automated injector is an equivalent alternative to manual injections.

Journal of Vascular and Interventional Radiology, 1996

« PreviousNext »Journal of Vascular and Interventional Radiology Volume 7, Issue 6 , Pages 813-81... more « PreviousNext »Journal of Vascular and Interventional Radiology Volume 7, Issue 6 , Pages 813-817, November 1996. Embolization of Backbleeding Lumbar Arteries Filling an Aortic Aneurysm Sac after Endovascular Stent-Graft Placement☆. Neil M. Khilnani, MD: Affiliations. ...

Journal of Vascular and Interventional Radiology, 1998

To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensio... more To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA). Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found. Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively. Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.

Journal of Magnetic Resonance Imaging, 2004

To evaluate visualization inside platinum stents with three-dimensional contrast-enhanced magneti... more To evaluate visualization inside platinum stents with three-dimensional contrast-enhanced magnetic resonance angiography (CE-MRA). Breath-hold three-dimensional gadolinium (Gd) MRA was performed on 18 patients with 22 platinum stents in the renal (n = 18), celiac (n = 1), superior mesenteric (n = 1), and iliac (n = 2) arteries. Electronic calibers were used to measure the lumen diameter within the stent and just distal to the stent to calculate percent stenosis. MRA accuracy was determined from the difference between percent stenosis measured on MRA and digital subtracted angiography (DSA). The patients were imaged at flip angles of 45 degrees , 60 degrees , 75 degrees , 90 degrees , and 150 degrees . MRA demonstrated the stent lumen in all of the patients, with a mean difference between MRA and DSA of 21%. For stents oriented parallel to B0 (iliac arteries) the difference was only 10%, as compared to 22% for stents perpendicular to B0. The flip angle with the best agreement between MRA and DSA was 75 degrees (16%). The lumen of a platinum stent can be imaged with three-dimensional CE-MRA, although grading of restenosis has limited accuracy. The best results were obtained with a flip angle of 75 degrees and for stents in the iliac arteries parallel to B0.

Journal of Magnetic Resonance Imaging, 2004

To evaluate the incidence and locations of soft tissue enhancement on time-resolved two-dimension... more To evaluate the incidence and locations of soft tissue enhancement on time-resolved two-dimensional projection magnetic resonance angiography (MRA) of the calf and foot. Time-resolved two-dimensional projection MRA of the knee, calf, and foot, performed at 1.5 Tesla using the head coil, was retrospectively reviewed in 326 patients. Soft tissue enhancement of the foot was identified and graded by blinded review. Subsequently, patient medical records were reviewed to determine the presence or absence of diabetes, cellulitis, gangrene, and ulceration of the foot and presence of neuropathic joints. Enhancing spots were identified in 228 patients. For those feet without clinical abnormalities, diabetic patients had an average of 1.2 enhancing spots per foot, while nondiabetics had only 0.6 (P < 0.001). Higher-grade lesions were more prevalent in diabetics and in heavier patients. Of 64 patients with follow-up, 8 (13%) developed cellulitis (N = 4) or ulceration (N = 4) at the location of an enhancing spot, including 5 diabetic and 3 nondiabetic patients. Pedal soft tissue enhancement frequently occurs on time-resolved gadolinium (Gd):MRA of the feet. The etiology is uncertain, but the high frequency in diabetic patients and observation of progression to cellulitis/ulceration suggest this soft tissue enhancement may identify sites of subclinical pedal soft tissue injury.

Investigative Radiology, 2002

To investigate the phenomena and causes for undesired venous signal in the distal station of bolu... more To investigate the phenomena and causes for undesired venous signal in the distal station of bolus chase 3D MRA. Consecutive patients (in 8 months) undergoing peripheral MRA consisting of 2D projection MRA of the tibial trifurcation and 3D bolus chase MRA were retrospectively evaluated. Venous contamination in mid-calf in bolus chase 3D MRA was correlated to the arterial phase duration, the time between the contrast bolus arrival and venous return measured on time resolved 2D images. Statistical analyses were performed to identify the clinical parameters indicative of venous contamination. The arterial phase durations at the mid-calf were 49 +/- 8 seconds on 101 legs without venous signal in the bolus chase 3D MRA, 35 +/- 9 seconds on 13 legs with moderate venous signal, and 20 +/- 4 seconds on 40 legs with substantial venous signal; the differences were significant among different venous signal levels (P < 0.001 for all pairs). Legs with cellulitis had shorter arterial phase and more venous contamination than legs without cellulitis (P < 0.05). Patients with myocardial infarction had longer arterial phase and less venous contamination than patients without myocardial infarction (P < 0.01). Venous signal in the distal calf station of bolus chase 3D peripheral MRA is caused by fast arterial-venous transit. It is worse in legs with cellulitis and less in patients with a history of myocardial infarction.

Investigative Radiology, 2001

The purpose of this study was to identify the cross-sectional location of collateral vessels in p... more The purpose of this study was to identify the cross-sectional location of collateral vessels in patients with peripheral vascular disease on three-dimensional magnetic resonance angiograms (3D MRAs) to suggest sites for intravascular or transcutaneous angiogenesis gene delivery in the lower extremity. The axial locations were measured and categorized by tissue compartments, as well as by radial coordinates with respect to the femur. Collateral vessels in the thigh were identified in 24 of 93 consecutive patients who underwent peripheral 3D MRA. Ninety-one percent (99/109) of the observed collaterals were located near the adductor canal level of the thigh, with 78% (31/46) of these collaterals located in the fat in or surrounding the posterior muscle. The majority of collateral vessels in the thigh are located in the fat or muscle within the posterior compartment near the femur at the level of the adductor canal.

Investigative Radiology, 2001

Wang Y, Winchester PA, Khilnani NM, et al. Contrast-en-hanced peripheral MR angiography from the ... more Wang Y, Winchester PA, Khilnani NM, et al. Contrast-en-hanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170 –177. ...