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Biomedical subjects

G A Holland

Publications and source records attributed to G A Holland.

At least 19 recordsLinked to original sources
PubMed2001

Ultrafast three-dimensional contrast-enhanced magnetic resonance angiography and imaging in the diagnosis of partial anomalous pulmonary venous drainage.

OBJECTIVES: The purpose of our study was to evaluate patients with suspected anomalous pulmonary veins (APVs) and atrial septal defects (ASDs) using fast cine magnetic resonance imaging (MRI) and ultrafast three-dimensional magnetic resonance angiography (MRA). BACKGROUND: Precise anatomic definition of anomalous pulmonary and systemic veins, and the atrial septum are prerequisites for surgical correction of ASDs. Cardiac catheterization and transesophageal echocardiography (TEE) are currently used to diagnose APVs, but did not provide complete information in our patients. METHODS: Twenty consecutive patients with suspected APVs were studied by MRA after inconclusive assessment by catheterization, TEE or both. The MRI images were acquired with a fast cine sequence and a novel ultrafast three-dimensional sequence before and after contrast injection. RESULTS: Partial anomalous pulmonary venous drainage was demonstrated in 16 of 20 patients and was excluded in four patients. Magnetic resonance imaging correctly diagnosed APVs and ASDs in all patients (100%) who underwent surgery. For the diagnosis of APVs, the MRI and catheterization results agreed in 74% of patients and the MRI and TEE agreed in 75% of patients. For ASDs, MRI agreed with catheterization and TEE in 53% and 83% of patients, respectively. CONCLUSIONS: Fast cine MRI with three-dimensional contrast-enhanced MRA provides rapid and comprehensive anatomic definition of APVs and ASDs in patients with adult congenital heart disease in a single examination.

Adult↗
PubMed2001

Rapid MR imaging detection of renal cysts: age-based standards.

PURPOSE: To establish age-based standards for renal cysts depicted at magnetic resonance (MR) imaging and to compare these standards with existing standards for ultrasonography (US). MATERIALS AND METHODS: Three radiologists reviewed subsecond T2-weighted single-shot fast spin-echo kidney MR imaging findings in 528 patients (248 men, 280 women) selected from consecutive abdominal MR studies without regard to clinical indication. Age, sex, and number and diameter of cysts were noted. Results were analyzed with nonparametric tests and were compared with published US results. RESULTS: Men (mean, 2.0; 95% CI: 1.5, 2.5) had more renal cysts than women (mean, 1.2; 95% CI: 0.9, 1.5) (P < .001). Number and diameter of cysts increased with age (P < .001). Of 528 patients, 330 (62.5%) had at least one renal cyst, and 315 (59.7%) had cysts of 10 mm or less. MR imaging findings were comparable to published US criteria for type 1 autosomal dominant polycystic kidney disease (ADPKD) if only cysts larger than 1 cm were considered: Only one subject in the group of 18-29-year-old subjects had at least two renal cysts, and five of 493 subjects aged 30-59 years had at least two cysts in each kidney. CONCLUSION: Compared with reported US results, MR imaging depicted an increased number of simple renal cysts in healthy individuals because of its increased sensitivity for cysts smaller than 1 cm. If only simple renal cysts larger than 1 cm are considered, US criteria for type 1 ADPKD can be applied to MR imaging.

Adolescent↗
PubMed2001

Liver lesion conspicuity: T2-weighted breath-hold fast spin-echo MR imaging before and after gadolinium enhancement--initial experience.

PURPOSE: To evaluate the effect of a gadolinium chelate on T2-weighted breath-hold fast spin-echo magnetic resonance images of focal hepatic lesions. MATERIALS AND METHODS: In 21 patients with focal hepatic lesions, identical T2-weighted breath-hold fast spin-echo images were obtained before and after gadolinium enhancement and were compared regarding lesion-to-liver contrast-to-noise ratio, signal-to-noise ratio, lesion conspicuity, and vascular pulsation artifact. Image review was performed independently, in random order, by two experienced radiologists. RESULTS: For solid lesions, the lesion-to-liver contrast-to-noise ratio on enhanced images was significantly higher (P <.05) than that on nonenhanced images. For nonsolid lesions, however, there was no significant difference (P =.07). For both readers, lesion conspicuity for solid lesions on enhanced images was significantly higher than on nonenhanced images (P <.05). Severity of vascular pulsation artifact was not significantly different. CONCLUSION: Solid-lesion contrast on T2-weighted breath-hold fast spin-echo images improves after administration of a gadolinium chelate. These images should be obtained after, rather than before, gadolinium enhancement.

Adult↗
PubMed1998

Intraoperative ultrasonographically guided cryoablation of renal masses: initial experience.

The purpose of this study was to evaluate the feasibility of intraoperative ultrasonography to guide cryoablation of renal masses. Renal cryoablation was performed on six patients with solid renal tumors. Under ultrasonographic guidance, cryoprobes measuring 3 mm in diameter were placed into the renal tumor parenchyma or into surrounding normal parenchyma. Intraoperative ultrasonography accurately delineated tumor size, cryoprobe placement, and depth of freezing. An echogenic interface was generated by the marked impedance differences at the junction of the normal renal parenchyma and frozen tissue. In addition, intraoperative ultrasonography identified a total of nine additional lesions in three patients that were not detected by preoperative imaging. These lesions also were treated cryosurgically during the same operation. There were no deaths. The patients have been followed with clinical and laboratory assessments as well as with MR imaging or CT scanning, and all have remained tumor free 3 to 22 months postoperatively. Ultrasonographically guided renal cryoablation is a feasible technique for treating malignant renal tumors while preserving renal parenchyma. Long-term follow-up studies in a larger series of patients are required to determine the true efficacy and safety of this procedure.

Aged↗
PubMed1997

Magnetic resonance angiography of the aortic arch.

Duplex ultrasound and magnetic resonance angiographic (MRA) studies are the principal noninvasive methods for evaluation of extracranial occlusive disease in patients at risk for stroke, but each has limited ability to diagnose aortic arch and arch vessel disease. Recent favorable reports of the nonnephrotoxic contrast agent Gadolinium (Gd) being used to enhance MRA images of the abdominal aorta prompted us to examine its utility for the aortic arch vessels. Prospectively, 28 patients with suspected carotid or arch vessel disease were imaged by contrast arteriographic examination and MRA + Gd of the aortic arch within 30 days of each other. One (for contrast arteriograms) or two (for MRA) blinded readers measured stenoses with the contrast arteriograms as the standard. A total of 196 arch vessels containing 58 stenoses and four occlusions (by arteriogram) were examined with each method. Interobserver agreement for interpretation of MRA studies was substantial (kappa = 0.68). MRA detected all anatomic anomalies (e.g., bovine arch). The correlation of MRA with arteriographic scans for arch vessel stenoses > 50% was sensitivity, 73% (readers 1 and 2); specificity, 98% (reader 1), 89% (reader 2); positive predictive value, 73% (reader 1), 89% (reader 2); negative predictive value, 98% (readers 1 and 2); accuracy, 97% (reader 1), 98% (reader 2). MRA + Gd is an accurate new noninvasive imaging method for detection of significant aortic arch disease. In its current state of development, however, it cannot obviate the need for contrast arteriographic examination.

Aorta, Thoracic↗
PubMed1997

Aortic dissection in a patient receiving chemotherapy for Hodgkin's disease--a case report.

Cancer chemotherapy is associated with a wide range of vascular toxicities, which may be related to endothelial cell damage by these agents. The authors describe a patient with Hodgkin's disease who developed an atypical aortic dissection while receiving MOPP/ABV chemotherapy (nitrogen mustard, vincristine, procarbazine, prednisone, doxorubicin, bleomycin, and vinblastine). They would place aortic dissection on the list of potential vascular complications associated with antineoplastic agents.

Adult↗
PubMed1996

The fate of bypass grafts to angiographically occult runoff vessels detected by magnetic resonance angiography.

PURPOSE: Magnetic resonance angiography (MRA) is a noninvasive vascular imaging technique that is more sensitive than contrast arteriography (CA) for the detection of patent distal runoff vessels. This technique has facilitated performance of MRA-directed bypass procedures for patients who were believed not to be bypass candidates because of the absence of a suitable target vessel on the preoperative CA. The fate of bypasses to these angiographically occult runoff vessels is unknown, however, and it has been proposed that patients with angiographically occult runoff may have aggressive occlusive disease, rendering bypass procedures ultimately futile. METHODS: Between April 1992 and February 1995, 212 autogenous vein infrageniculate bypasses were performed for limb-salvage indications, 22 (12%) to angiographically occult runoff vessels. Results of bypasses performed to angiographically occult vessels were compared with those of bypasses to CA-detected runoff vessels. Life-table analysis of graft-patency and limb-salvage rates was performed. RESULTS: The accuracy of the MRA-predicted patency of angiographically occult vessels was confirmed in every case by the operative findings. Life-table analysis revealed no significant difference in primary graft patency (p > 0.05) or limb-salvage (p > 0.05) rates between patients with bypasses to runoff vessels seen by MRA alone. At 35 months after surgery, the primary graft patency rate was 68% for bypasses to CA-detected vessel bypass and 67% for MRA-detected vessels. The limb salvage rate was 83% for CA-detected vessel bypass patients and 78% for patients with angiographically occult runoff. CONCLUSIONS: MRA can accurately identify patent runoff vessels not visualized by CA. Results of bypasses performed to angiographically occult runoff vessels are similar to those of bypasses performed to vessels detected by CA. MRA should be performed in patients in whom CA fails to reveal runoff vessels suitable for use in a limb-salvage procedure. The greater sensitivity of MRA may facilitate successful bypass surgery and improve the overall limb-salvage rate.

Aged↗
PubMed1996

Pulmonary MR angiography.

Recent technical improvements have made pulmonary MR angiography (MRA) feasible. The technique is attractive because it is noninvasive, provides a full three-dimensional (3D) display of the pulmonary vasculature, and potentially can be combined with MR venography of the lower extremities and pelvis for the comprehensive diagnosis of thromboembolism. Approaches to acquiring pulmonary MR angiograms are currently being developed and include both two-dimensional and 3D time-of-flight methods, breath-hold and non-breath-hold techniques, and the use of gadolinium-based contrast enhancement. The results of initial studies using pulmonary MRA for the detection of pulmonary embolism are encouraging, but they must be evaluated in conjunction with newly developed fast CT scanning techniques. This article reviews the state of development of pulmonary MRA, the current clinical applications of the technique, and the prospects for future development.

Humans↗
PubMed1996

Breath-hold ultrafast three-dimensional gadolinium-enhanced MR angiography of the aorta and the renal and other visceral abdominal arteries.

OBJECTIVES: The objectives of this study were to develop and show the efficacy of a breath-hold ultrafast three-dimensional (3D) spoiled gradient-echo (SPGR) gadolinium-enhanced MR angiographic technique for imaging the aorta and the renal and other visceral arteries of the abdomen; and to compare breath-hold ultrafast 3D SPGR with two-dimensional (2D) time-of-flight (TOF) and non-breath-hold ultrafast 3D SPGR in the same patients. SUBJECTS AND METHODS: We prospectively studied the abdominal aorta and the renal and other visceral arteries 68 times in 63 consecutive patients with 2D TOF and ultrafast 3D SPGR MR angiography. Thirty-two patients had contrast angiography (n = 23) and/or surgery (n = 24) to serve as a gold standard. All MR imaging studies were performed on a 1.5-T scanner (General Electric Medical Systems, Milwaukee, WI) using an enhanced gradient system with maximum gradient strength of 2.3 gauss/cm reached in 150 microseconds. Axial 2D TOF parameters were: TR/TE, 33/5.5 msec; flip angle, 45 degrees; slice thickness, 2 mm; and no presaturation pulses. Coronal ultrafast 3D SPGR was performed before and after the i.v. administration of 40-60 cc of gadolinium. For the coronal ultrafast 3D SPGR, our parameters were: TR/TE, 4.8-7/1.1; flip angle, 60 degrees; 28-50 slices of 2.0-2.6 mm thickness; and acquisition time, 18-32 sec. Studies were read by a single radiologist [corrected] and were evaluated for the degree of stenosis in the renal, celiac, superior mesenteric, and inferior mesenteric arteries; any vascular anomalies (i.e., retroaortic renal veins and accessory renal or variant hepatic arteries) were noted. RESULTS: Breath-hold ultrafast 3D SPGR correctly identified 31 of 31 stenoses of the renal artery for a sensitivity, specificity, and accuracy of 100%. Two-dimensional TOF detected 23 of 31 renal artery stenoses for a sensitivity, specificity, and accuracy of 74%, 98%, and 87% respectively. Breath-hold ultrafast 3D SPGR underestimated two renal arteries as having severe osteal stenoses that were graded correctly by 2D TOF and by angiography as occlusions. Eight of nine (89%) accessory renal arteries were correctly identified with breath-hold ultrafast 3D SPGR: Two-dimensional TOF identified six of nine (67%). Breath-hold ultrafast 3D SPGR identified one accessory and two reconstituted renal arteries missed by 2D TOF and conventional contrast angiography that were confirmed at surgery. Ultrafast 3D SPGR and 2D TOF correctly identified 20 of 20 celiac, superior mesenteric, and inferior mesenteric artery osteal stenoses or occlusions for a sensitivity, specificity, and accuracy of 100%. Three Riolan's arcs were correctly identified by breath-hold 3D SPGR but were missed by 2D TOF: Forty of the 63 patients did not have conventional contrast angiography and were managed surgically (n = 9) or medically (n = 31) based on the results of the MR angiograms and clinical data. Breath-hold ultrafast 3D SPGR MR angiography correctly identified and graded 48 of 51 renal, celiac, superior mesenteric, and inferior mesenteric artery stenoses or occlusions. Two-dimensional TOF MR angiography correctly identified and graded 45 of 51 renal, celiac, superior mesenteric, and inferior mesenteric artery stenoses and occlusions. CONCLUSION: Breath-hold ultrafast 3D SPGR when combined with 2D TOF accurately identified and graded all (51 of 51) renal, celiac, superior mesenteric, and inferior mesenteric artery stenoses or occlusions.

Adolescent↗
PubMed1995

Endovascular stent placement and magnetic resonance angiography for management of hypertension and renal artery occlusion during pregnancy.

BACKGROUND: Severe renovascular hypertension carries serious maternal and fetal risk. In patients failing medical therapy, therapeutic options include surgical revascularization, nephrectomy, and percutaneous angioplasty. CASE: A pregnant woman with long-standing hypertension developed accelerated hypertension despite multiple drug therapy. Magnetic resonance angiography diagnosed an atrophic kidney with a critical proximal right renal artery lesion. At 17 weeks' gestation, this renal artery occlusion was treated with percutaneous angioplasty and endovascular stent placement; hypertension has improved markedly, allowing discontinuation and tapering of her antihypertensive medications. Total fetal radiation dose was 0.002 Gy. CONCLUSION: Magnetic resonance angiography is a promising, noninvasive diagnostic method of evaluating renovascular hypertension during pregnancy. Transluminal angioplasty and endovascular stent placement can be performed safely and effectively with nominal fetal radiation exposure.

Adult↗
PubMed1995

Magnetic resonance angiography of the distal lower extremity.

OBJECTIVE: To assess magnetic resonance angiography (MRA) for demonstration of arterial patency in the ankle and foot of patients with peripheral vascular disease. METHODS: Peripheral MRA of the ankle and foot was performed on 34 limbs of 31 insulin-dependent diabetics. 2-D time-of-flight MRA (TR 33 ms/TE 7.7 ms/inferior saturation band) was performed with 16 cm field of view. Pre- or intra-operative angiographic correlation was available in all cases. RESULTS: In 24 limbs MRA was compared to conventional angiography. MRA showed more patient run-off vessel segments (120) than angiography (100). In 10 limbs MRA was compared to intraoperative angiography and for the detection of patent vessel segments showed a sensitivity of 87.5% (42/48) with a 95% confidence interval of 75% to 95% and a specificity of 95% (38/40) with a 95% confidence interval of 83% to 99%. Pitfalls included difficulty in visualizing flow at the bifurcation of the peroneal artery, in the plantar arch and retrograde flow in the lateral plantar artery. CONCLUSIONS: MRA is sensitive for the detection of patent arteries in the ankle and foot but artefacts may cause overdiagnosis of focal stenoses or occlusions.

Aged↗
PubMed1995

Pulmonary thromboembolism: recent developments in diagnosis with CT and MR imaging.

Recent technical advances in computed tomography (CT; helical and electron beam) and magnetic resonance (MR) imaging have spurred a renewed interest in these modalities for the diagnosis of acute and chronic pulmonary embolism (PE). These techniques can enable accurate clot detection down to segmental pulmonary arteries, with CT currently allowing more accuracy than that with MR imaging. Ongoing technical advances, particularly in MR angiography, will likely increase diagnostic accuracy. Inability to reliably detect subsegmental acute emboli may not prove to be a clinically significant limitation if lung imaging is coupled with evaluation for deep venous thrombosis. MR imaging can potentially accomplish this within a single examination. Incorporation of CT and MR imaging into diagnostic algorithms for suspected PE can be cost-effective. Evaluation of these new modalities should be based on patient outcome, not solely on clot detectability. Well-designed clinical trials are warranted before CT and MR imaging can be used routinely in the diagnosis of acute PE.

Acute Disease↗
PubMed1994

Preliminary experience with magnetic resonance venography: comparison with findings at surgical exploration.

While conventional magnetic resonance imaging has been described for the evaluation of the venous system, we have recently developed the technique of magnetic resonance venography (MRV), which generates three-dimensional projection venograms. Our purpose was to determine if MRV reliably images the venous system by comparison with findings at surgical exploration. Thirteen of fourteen consecutive patients undergoing bypass surgery (26 limbs) were studied by 2D time-of-flight MRV preoperatively from the inguinal ligament to the ankle bilaterally. The average examination time was 50 min. The size and quality of each saphenous vein were recorded at the saphenofemoral junction, mid-thigh, knee, mid-calf, and malleolus. Intraoperatively the quality and size of each vein were measured in situ and when distended by saline. Twelve veins were of good quality. MRV predicted this in every case. One vein, found to be recanalized, had an abnormally thick wall noted on MRV. MRV measurements of average vein size were intermediate between that of the in situ and distended vein and correlated most closely with the distended vein (R = 0.74, P < 0.001). The superficial and deep femoral veins and lesser saphenous veins were routinely visualized by MRV; thus a complete map of all available vein was obtained by a single study. It is concluded that MRV is an accurate method of venous imaging as confirmed by findings at operative exploration. This new technique holds promise as a noninvasive method for evaluation of the venous system and warrants further investigation.

Coronary Artery Bypass↗
PubMed1994

Peripheral vascular surgery with magnetic resonance angiography as the sole preoperative imaging modality.

PURPOSE: Magnetic resonance angiography (MRA) is a developing technique that provides arteriograms without the risks associated with iodinated contrast and arterial puncture or the expense of hospitalization. Prior reports have demonstrated the accuracy of peripheral vessel MRA for evaluation of the aorta through pedal vessels. This study sought to determine whether vascular reconstructions could be planned and accomplished on the basis of MRA alone. METHODS: Eighty consecutive candidates for bypass with ischemic rest pain or tissue loss were studied with preoperative outpatient MRA of the juxtarenal aorta through the foot. Confirmation of MRA findings was provided by intraoperative intraarterial pressure measurements for proximal vessels and postbypass arteriography for the runoff. Life-table analysis of graft patency and limb salvage was performed. RESULTS: Two patients could not tolerate MRA and required contrast arteriography, but all others underwent reconstructive procedures on the basis of MRA alone (11 aortobifemoral, 67 infrainguinal). Intraoperative findings regarding suitability of inflow and outflow vessels confirmed the accuracy of the MRAs in every case. MRA indicated that none of the patients undergoing infrainguinal bypass had significant inflow occlusive disease, and this was confirmed at operation with pressure measurements of inflow vessels that were always within 10 mm Hg (peak systolic) of systemic pressure. The results of intraoperative completion arteriography and preoperative MRAs were identical for all but two patients who had minor discrepancies. All aortobifemoral reconstructions remained patent, and all limbs remained intact. The infrainguinal reconstructions had an 84% limb salvage rate and 78% primary graft patency rate at 21 months. Comparison of charges for patients undergoing preoperative MRA versus contrast angiography showed a cost savings of $1288 for each patient treated with preoperative MRA alone. CONCLUSIONS: MRA is a noninvasive, cost-effective outpatient imaging technique that, if properly performed and interpreted, is sufficient for planning peripheral bypass procedures. Its use may supplant contrast arteriography in many patients.

Adult↗
PubMed1994

Evaluation of renal artery stenosis by magnetic resonance angiography.

BACKGROUND: Accurate identification of patients with surgically correctable renovascular hypertension has been difficult by noninvasive means. Advances in the technique of magnetic resonance angiography (MRA) have begun to provide detailed, accurate imaging of the vascular system. This study reports our recent experience in the evaluation of the renal arteries by this technique. METHODS: MRA and contrast arteriography were performed in 32 arteries (16 adult patients) for evaluation of hypertension, abdominal aortic aneurysm, mesenteric vascular disease, and aorto-iliac occlusive disease. Luminal diameter reduction (%) was determined from two-dimensional time-of-flight (TOF) axial images. Contrast arteriography served as the gold standard for comparison. RESULTS: Contrast arteriography revealed a 50% or greater stenosis in 11 of 32 vessels studied (34%). As a screening test for detection of greater than 50% diameter reduction, MRA had a sensitivity of 91%, a negative predictive value of 94%, and an overall accuracy of 81%. Linear regression analysis demonstrated significant correlation between MRA and arteriographic measurements (r = 0.8; P < 0.001). CONCLUSIONS: This study demonstrates the ability of MRA to accurately assess the main renal arteries for the presence of critical stenosis. This noninvasive evaluation compares well with conventional angiography and may have increasing application in the screening of patients with suspected renovascular disease.

Adult↗
PubMed1994

Magnetic resonance angiography of the aorta, iliac, and femoral arteries.

BACKGROUND: Successful management of patients with peripheral vascular disease requires detailed vascular imaging, usually performed by contrast arteriography. Recently, magnetic resonance angiography (MRA) has been shown to be a noninvasive technique with greater sensitivity than contrast arteriography for detecting distal runoff vessels in patients with peripheral arterial occlusive disease. However, to supplant the need for contrast arteriography and provide a completely noninvasive evaluation of patients with occlusive disease, accurate imaging of the inflow vessels and the runoff vessels is necessary. METHODS: We used both conventional arteriography and MRA in preoperative studies of the aorta, iliac, and femoral vessels of 47 patients. Conventional arteriography and MRA studies were compared for their ability to detect vessel patency and the presence of hemodynamically significant stenoses. Independent interventional plans were developed based on the information provided by each technique. The findings of conventional and MRA studies were verified by intraoperative arteriography or direct operative exploration. RESULTS: Results of the two studies were identical in 41 (87%) of 47 patients or 600 (98%) of 614 segments imaged. MRA accurately detected patent and occluded arterial segments (sensitivity 99.6%, specificity 100%, positive predictive value 100%, negative predictive value 98.6%) and hemodynamically significant stenoses. Therapeutic plans based on either MRA or conventional arteriography were identical for each patient. CONCLUSIONS: MRA provides comparable results to contrast arteriography in the proximal arterial system and superior results for imaging the distal vasculature. This noninvasive technique may replace contrast arteriography in a large number of patients in the future.

Adult↗