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Purpose: To prospectively assess patient response (after 12 months) to magnetic resonance (MR) imaging-guided focused ultrasound surgery in treatment of uterine leiomyomas by using two treatment protocols., Materials and Methods: This prospective clinical trial was approved by institutional review boards and was HIPAA compliant. After giving informed consent, patients with symptomatic leiomyomas were consecutively enrolled and treated at one of five U.S. centers by using an original or a modified protocol. Outcomes were assessed with the symptom severity score (SSS) obtained at baseline and 3, 6, and 12 months after treatment. Adverse events (AEs) were recorded. Statistical analysis included Student t test, Fisher exact test, analysis of covariance, Spearman correlation, and logistic regression., Results: One hundred sixty patients had a mean SSS of 62.1 +/- 16.3 (standard deviation) at baseline, which decreased to 35.5 +/- 19.5 at 3 months (P<.001) and to 32.3 +/- 19.8 at 6 months (P<.001) and was 32.7 +/- 21.0 at 12 months (P<.001). Ninety-six patients (mean age, 46.0 years +/- 4.6) were treated with an original protocol, and 64 (mean age, 45.9 years +/- 3.9) were treated with a modified protocol. Patients in the modified group had a significantly greater SSS decrease at 3 months (P=.037) than those in the original group, and 73% of those in the original group and 91% of those in the modified group reported a significant decrease in SSS (of 10 points or greater) at 12 months. No serious AEs were recorded. Fewer AEs were reported in the modified group than in the original group (25% vs 13% reporting no event). Of evaluable patients, fewer in the modified group chose alternative treatment (28%) than in the original group (37%)., Conclusion: MR imaging-guided focused ultrasound surgery results in symptomatic improvement, sustained to 12 months after treatment. Treatment with a modified protocol results in greater clinical effectiveness and fewer AEs., ((c) RSNA, 2007)

Purpose: To determine the diagnostic performance of functional magnetic resonance cholangiography (fMRC) for the evaluation of anatomic and functional biliary disorders., Materials and Methods: At 1.5 T, 39 MR examinations with conventional MRC and mangafodipir trisodium-enhanced fMRC were retrospectively reviewed by three observers who recorded anatomic (duct dilation, stricture, filling defects) and functional (cholecystitis, obstruction) abnormalities in three modes: MRC alone, fMRC alone, and MRC and fMRC images together (combined-MRC). Performance was determined by comparing findings with each mode to findings of invasive cholangiography (IC) and surgery., Results: Among 75 biliary segments (correlated with IC), the sensitivity/specificity for diagnosing dilation (N = 41) with MRC was 95%/97%; with fMRC, 90%/100%; with combined-MRC, 100%/97%. For stricture (N = 7), the sensitivity/specificity of MRC was 86%/98%; of fMRC, 43%/100%; of combined-MRC, 86%/100%. For filling defects (N = 9), the sensitivity/specificity of MRC was 91%/98%; of fMRC, 82%/100%; of combined-MRC, 91%/100%. For diagnosing obstruction (N = 9), the sensitivity/specificity of MRC, fMRC, and combined-MRC were 89%/100%, 100%/100%, and 100%/100%, respectively. For surgically proven cholecystitis (N = 13), positive predictive values for diagnosing acute/chronic cholecystitis for MRC were 33%/40%; for fMRC, 100%/50%; for combined-MRC, 100%/50%., Conclusion: Although single-shot fast spin echo (SSFSE)-MRC is valuable, the addition of fMRC increased diagnostic performance for functional biliary disorders., (Copyright 2003 Wiley-Liss, Inc.)

Purpose: To compare the safety and effectiveness of an undiluted direct injection of ferumoxides with those of a diluted slow infusion of ferumoxides during 30 minutes in patients with known liver lesions or in those suspected of having them., Materials and Methods: Two hundred thirty-three patients at 16 institutions were randomized to receive either an undiluted direct injection of 0.56 mg of iron per kilogram of body weight of ferumoxides administered during 2 minutes (2 mL/min) or a diluted slow infusion administered during 30 minutes. Safety was assessed with monitoring for adverse events and laboratory tests. For sensitivity, specificity, and accuracy analysis, two independent blinded observers identified and classified lesions as benign or malignant with precontrast images and with pre- and postcontrast images combined., Results: There was no statistically significant difference in adverse events in the group with direct injection compared with those in the group with infusion (21 [18%] of 114 patients vs 19 [17%] of 112 patients, respectively). No serious adverse events were observed. The most common adverse events in the group with direct injection versus the group with infusion were headache (five [4%] of 114 vs three [3%] of 112, respectively) and back pain (five [4%] of 114 vs three [3%] of 112, respectively). Overall, in 68 (62%) of 109 patients with direct injection and 71 (66%) of 108 patients with infusion, additional magnetic resonance (MR) imaging information was obtained after ferumoxides administration (P =.67). Sensitivity, specificity, and accuracy for the diagnosis of malignancy were significantly improved by adding images obtained after ferumoxides administration to the images obtained before contrast agent administration (P <.05 for all comparisons)., Conclusion: Direct injection of ferumoxides has safety and effectiveness profiles similar to those of slow infusion of the agent. Further findings indicate that the addition of ferumoxides increases the sensitivity and specificity of hepatic MR evaluation when compared with unenhanced MR imaging., (Copyright RSNA, 2003.)

Purpose: To assess whether measuring the pattern of pancreatic enhancement on gadolinium chelate dynamic magnetic resonance imaging (MRI) is helpful for diagnosis of suspected early or mild chronic pancreatitis., Materials and Methods: In this retrospective study, 24 patients with suspected early or mild chronic pancreatitis, classified by imaging criteria of equivocal chronic pancreatitis (ultrasound, computed tomography [CT] or ERCP) grading, had dynamic MRI that included unenhanced, arterial dominant, early venous, and late venous phases of contrast enhancement. Twenty patients without pancreatic diseases also had the dynamic sequence as a control group. The signal intensity was measured at the pancreatic head, body, and tail on all phases, and for each, the signal intensity ratio (SIR, the signal intensity in postcontrast divided by that in precontrast) was calculated. Two radiologists independently reviewed the images of the patients with suspected early or mild chronic pancreatitis for pancreatic morphologic abnormalities without knowing the results of signal intensity measurements., Results: On unenhanced images, there was no significant difference of signal intensity between control and pancreatitis groups (P < 0.05). In the pancreatitis group, but not in the control group, the unenhanced signal intensity of the pancreatic head and body were significantly higher than that of the tail (P < 0.05). In the control group, the greatest enhancement (highest SIR) after injection was in the arterial phase (1.89 +/- 0.31), significantly higher than that in the early venous phase (1.68 +/- 0.17, P < 0.01) and in the late venous phase (1.61 +/- 0.15, P < 0.001). The pancreatitis group, however, had an arterial phase SIR (1.65 +/- 0.23) that was significantly lower than its early venous phase SIR (1.75 +/- 0.22, P < 0.05) and lower than the arterial phase SIR of the control group (P < 0.01). The presence of an SIR less than 1.73 in the arterial phase and/or a delayed peak enhancement after contrast agent administration had a sensitivity and specificity of diagnosing early or mild chronic pancreatitis of 92% and 75%, respectively. This sensitivity was significantly higher than the sensitivity of 50% for diagnosis based on morphologic abnormalities (P < 0.05)., Conclusion: Measuring pancreatic signal intensity on gadolinium chelate dynamic MRI is helpful for diagnosing early or mild chronic pancreatitis, especially before apparent pancreatic morphologic or signal intensity changes are present., (Copyright 2002 Wiley-Liss, Inc.)

Objective: To study the MR appearance of lymph nodes in relation to activity of chronic active hepatitis C, we correlated the findings on MR imaging with a histologic grading of the activity level., Materials and Methods: Fifty patients with chronic active hepatitis C, who had MR imaging examinations and a related histology report from a liver biopsy obtained within 1 month of the MR imaging were chosen from our radiology database and studied retrospectively. All patients were examined over a 4-year period at a single institution to detect cirrhosis or hepatocellular carcinoma. We divided the 50 patients into the mild, moderate, or severe activity groups, according to their histology reports. Two radiologists, unaware of the histologic classifications, individually reviewed the MR images to observe the perihepatic locations, number, size (defined as the sum of the length-by-width products of the largest three nodes), and intensity of the lymph nodes relative to the spleen. The clinical records of the patients were reviewed to check the results of their liver function tests. The lymph node findings on MR imaging were compared with the histologically confirmed activity level of chronic hepatitis C., Results: Forty-four (88.0%) of 50 patients had perihepatic lymph nodes larger than 5 mm on MR images, including 64.2% (9/14) of the patients with mild activity, 96.3% (26/27) of the patients with moderate activity, and 100% (9/9) of the patients with severe activity (p = 0.0034). The average number +/- the standard deviation (SD) of perihepatic lymph nodes was 2.5 +/- 1.8 in patients with mild activity, 5.6 +/- 2.2 in patients with moderate activity, and 8.3 +/- 3.5 in patients with severe activity (p = 0.0001). The average size (+/- SD) of the lymph nodes was 151.0 +/- 104.9 mm(2) in the mild activity group, 366.8 +/- 143.0 mm(2) in the moderate activity group, and 488.2 +/- 244.8 mm(2) in the severe activity group (p = 0.0001). On fat-saturated fast spin-echo T2-weighted MR images, the average number (+/- SD) of hyperintense nodes was 0.17 +/- 0.25 in the mild activity group, 1.7 +/- 0.80 in the moderate activity group, and 2.4 +/- 0.60 nodes in the severe activity group (p = 0.0001). No relationship between histologic activity and results from liver function tests was found., Conclusion: MR imaging depicts perihepatic lymph nodes in most patients with chronic hepatitis C. Lymph node number, size, and hyperintensity were related to the activity of chronic hepatitis C, but the results of liver function tests were not.

Purpose: To evaluate single-shot fast spin-echo (SE) magnetic resonance (MR) imaging for depiction of pancreatic cysts in a large number of patients and to analyze cyst prevalence with respect to patient age and sex and other clinical information., Materials and Methods: Single-shot fast SE images of the pancreas were obtained in 1,444 patients. The images were reviewed for presence of pancreatic cysts, which were classified as simple and nonsimple types, and cyst diameters were measured. kappa statistic, Fisher exact, McNemar Q, and Pearson product moment correlation tests were performed., Results: Two hundred eighty-three (19.6%) patients had at least one pancreatic cyst. The prevalence of pancreatic cysts increased with age (r = 0.96). The percentages of male and female patients with pancreatic cysts (20.4% vs 18.8%) were not significantly different. Two hundred seventy-one (18.8%) patients had simple cysts, and 147 (10.2%) had nonsimple cysts. Of 283 patients with pancreatic cysts, 158 (55.8%) had only one pancreatic cyst. The number of patients with multiple cysts increased with age after 70 years. Four hundred fifteen (83.8%) cysts were 10 mm in diameter or smaller; 56 (11.3%), 11-20 mm in diameter; and 24 (4.9%), 21 mm in diameter or larger. Sixteen (5.7%) patients with pancreatic cysts had malignant pancreatic tumors, and 75 (26.5%) patients had pancreatitis., Conclusion: The prevalence of pancreatic cysts at single-shot fast SE MR imaging-especially cysts with a diameter smaller than 10 mm-is similar to that of pancreatic cysts at autopsy and higher than that of pancreatic cysts at transabdominal ultrasonography. Prevalence is especially high in patients with pancreatitis., (Copyright RSNA, 2002)

We present a case of spontaneous rupture of hepatocellular carcinoma (HCC) with poor liver function which was treated by transcatheter arterial embolization (TAE). The patient's bilirubin value was 3.8 mg/dL. The tumor was fed by the right renal capsular artery according to selective arteriography. It was subsequently treated by TAE. With successful TAE, no hepatic failure was related to the treatment. We believe that if tumors are fed only by extrahepatic collateral vessels, TAE may be an effective treatment even in patients with poor liver function.

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.

As a preliminary study, we measured the necrosis of advanced hepatocellular carcinoma (HCC) by volume histogram after systemic chemotherapy and correlated it with clinical data. Five patients with advanced HCC secondary to chronic hepatitis and cirrhosis underwent pretreatment and posttreatment MR examination on a 1.5 T MR scanner following systemic chemotherapy. MR sequences included dynamic enhanced fast spoiled gradient echo 3D images. Clinical response to chemotherapy, as determined by MR images, was measured as changes of both the total tumor volume and the percent of tumor necrosis by volume histogram algorithm. Four of five patients had clinical improvement. Three of these patients had no or minimal change of tumor volume; however, there was an increase in tumor necrosis in follow-up MR image. One patient of five with no change in tumor necrosis had no response and died at 3 months. Serial MR images showed increased irregular necrosis of advanced HCC after systemic chemotherapy, but stable volume, in patients who responded clinically to systemic chemotherapy.

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.

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.

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.

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.

Gadolinium-enhanced ultrafast three-dimensional (3D) spoiled gradient-echo magnetic resonance (MR) imaging is a noninvasive method for evaluating the abdominal aorta and the visceral and iliac vessels. With an enhanced gradient system, 20-48 sections can be obtained during a single 18-32-second patient breath hold. The 3D volume obtained from a single acquisition can be reformatted at a workstation and the vascular anatomy viewed in any projection and with a variety of section thicknesses, making this MR imaging technique particularly useful in the evaluation of aberrant arteries, vascular stenoses, aneurysms, and dissection flaps. Gadolinium-enhanced ultrafast 3D spoiled gradient-echo MR imaging has been used instead of or in addition to conventional contrast material-enhanced MR angiography in patients who have chronic symptoms of mesenteric ischemia, who have abdominal aortic aneurysms, or who are at risk for iodinated contrast material-related renal dysfunction. This technique shows great promise for accurate and noninvasive evaluation of the abdominal aorta and the visceral and iliac vessels.

A single coronary artery is a rare cause of cardiac ischemia, congestive heart failure, and sudden death. We report the second known antemortem diagnosis of a single right coronary artery supplying the entire myocardium.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Unlabelled: Magnetic resonance angiography (MRA) provides detailed morphologic and flow information that demonstrates complex changes at sites of percutaneous transluminal angioplasty (PTA) and atherectomy. The purpose of this study is to examine the appearance of the vessel by MRA in the initial post-procedural and early follow-up periods., Methods: MRA was performed to evaluate 35 infrainguinal endovascular procedures (20 patients), including PTA (20), atherectomy (4), and combination PTA/atherectomy (11). MRA imaging was performed within 24 hours of the procedure and at a mean follow-up interval of 3.5 months (range 1-8)., Results: Abnormalities in the immediate post-procedural MRA were seen in 55% of the PTA group and 93% of the atherectomy group (p = 0.04). Importantly, three of 35 lesions (9%) were shown by MRA to harbor > 50% stenoses despite angiographically "successful" procedures. Follow-up MRA showed abnormalities in 25% of those undergoing PTA, and in 67% of those with atherectomy (p = 0.01). At the time of follow-up MRA, four areas showed > 50% stenosis and four areas showed occlusion, revealing unfavorable outcomes in 22%., Conclusions: MRA provides a detailed noninvasive image of the sites of endovascular interventions and reveals vessel wall abnormalities not appreciated by conventional arteriography. Continued observation may allow prediction of segments at increased risk for restenosis.

Purpose: Contrast venography is the gold standard for diagnosis in deep venous thrombosis (DVT); however, this technique is invasive and requires the use of potentially hazardous contrast agents. Although duplex Doppler ultrasonography is accurate in the evaluation of lower extremity DVT, it is less accurate in the assessment of the pelvic and intraabdominal veins. Magnetic resonance venography (MRV) has recently been developed, and our purpose was to determine whether MRV could accurately demonstrated DVT when compared with duplex scanning and contrast venography., Methods: Eighty-five patients underwent contrast venography and MRV from the inferior vena cava to the popliteal veins to rule out DVT. Thirty-three of these patients also underwent duplex scanning. Blinded readings of these studies were compared for the presence or absence and extent of venous thrombosis., Results: DVT was documented by contrast venography in 27 (27%) venous systems. Results of MRV and contrast venography were identical in 98 (97%) of 101 venous systems, whereas results of duplex scanning and contrast venography were identical in 40 (98%) of 41 venous systems. All DVTs identified by contrast venography were detected by MRV and duplex scanning. The discrepancies were due to false-positive MRV (3) and duplex scanning (1) results. When compared with contrast venography, MRV had a sensitivity of 100%, specificity of 96%, positive predictive value of 90%, and negative predictive value of 100%. For duplex scanning the sensitivity was 100%, specificity was 96%, positive predictive value was 94%, and negative predictive value was 100%., Conclusions: It is concluded that MRV is an accurate noninvasive venographic technique for the detection of DVT.

Purpose: To prospectively evaluate three magnetic resonance (MR) imaging techniques for detection of pulmonary embolism., Materials and Methods: Eighteen patients in whom the presence of acute or chronic pulmonary emboli was suspected underwent examination with the following pulse sequences: cardiac-gated spin echo, cine spatial modulation of magnetization, and two-dimensional time-of-flight pulmonary breath-hold (PBH) MR angiography. Three radiologists independently and blindly reviewed each case and graded a total of 518 arterial segments for each pulse sequence with a continuous scale of 0%-100% for likelihood of pulmonary embolism., Results: The overall sensitivity of PBH MR angiography for detection of acute pulmonary emboli was 0.85; for chronic emboli, which were smaller in anteroposterior (AP) diameter, the overall sensitivity was 0.42. Emboli larger than 1 cm in AP diameter were typically identified with > 75% confidence with all pulse sequences., Conclusion: Acute pulmonary emboli greater than 1 cm in AP diameter were as accurately identified on PBH MR angiograms obtained in 15 seconds as they were on MR images obtained with longer pulse sequences not dependent on breath holding.

Magnetic resonance angiography (MRA) has recently been shown to be more sensitive than contrast arteriography in the detection of patent distal runoff vessels. This study compares MRA and contrast arteriography in evaluating the severity of stenotic lesions in peripheral arteries, which has not been previously investigated. Forty-eight arterial stenoses (19 patients) were identified, from the distal aorta through the crural vessels. Contrast arteriograms (anterioposterior projection) and MRA axial images were used to measure stenoses. Interobserver agreement of arteriogram readings was excellent (average weighted k = 0.87). Measurements of degree of stenosis as evaluated by MRA and contrast arteriography were analyzed by linear regression and Spearman rank correlation, which showed a high degree of correlation between the two diagnostic modalities (r = 0.83, p < 0.001; rs = 0.84, p < 0.001). These observations suggest that MRA is accurate in the evaluation of peripheral arterial stenosis when compared with the "gold standard" contrast arteriogram. In addition, MRA cross-sectional images provide information beyond that of conventional arteriography, showing details of plaque eccentricity and vessel wall characteristics. In the future, MRA may supplant diagnostic contrast arteriography for many patients.

Purpose: Recent papers have hypothesized that diamagnetic effects of clotting and conformational changes in aging red blood cells immobilize the hemoglobin protein and thus are responsible for the marked hypointensity of acute hematomas on T2-weighted spin-echo MR images. To test that hypothesis, the authors evaluated 24 hemorrhagic components of intracranial hemorrhagic lesions using accepted criteria based on spin-echo images as the definitions of the stage of the hemorrhage., Methods: As a measure of the effects of macromolecular (hemoglobin protein) immobility, magnetization transfer contrast was elicited using a pulsed saturation magnetization transfer experiment. The apparent magnetization transfer contrast (AMTC) was determined by comparing the signal intensities of saturated with unsaturated images and quantified for acute isolated hemorrhages, acute nonisolated hemorrhagic lesions, and subacute-to-chronic hemorrhages., Results: The AMTC of isolated acute hemorrhage was significantly less than that of normal, white matter and gray matter, indicating the lack of significant magnetization transfer and therefore the lack of effects of restriction of hemoglobin mobility on the signal intensity of acute hemorrhage. Acutely hemorrhagic tissue (nonisolated acute hemorrhage) has significantly more AMTC than isolated acute hemorrhage, but still not exceeding that of brain parenchyma., Conclusion: This in vivo data concurs with in vitro data and reinforces the concept that the marked hypointensity of acute hematomas is mainly a magnetic susceptibility effect.

When failure of vein grafts is due to technical error it is usually observed in the early postoperative period. In this review we describe late failure of five bypass grafts as a result of entrapment of the vein graft caused by an improperly placed tunnel from the femoral to the popliteal artery. Vein graft entrapment may either produce no symptoms or eventually lead to limb ischemia. Pulses and pressures that vary with flexion and extension maneuvers should alert the clinician to the possibility of an entrapment syndrome. The characteristic arteriographic findings observed in these patients include an aberrant course of the vein graft outside the anatomic course of the popliteal artery and position-dependent compression of the graft. The ability of magnetic resonance angiography to demonstrate the arteriographic appearance of the graft as well as the precise location of the compression and to identify structures involved in the entrapment, make it a valuable noninvasive tool in the preoperative assessment of these patients. Treatment options include division of the gastrocnemius muscle, division of the vein graft, or replacement of the vein graft. Familiarity with vein graft entrapment should facilitate its recognition. Careful placement of bypass grafts along the anatomic course of the popliteal artery within the popliteal space will prevent this complication.

In the first phase of this study, seven healthy subjects underwent examination with two-dimensional time-of-flight (TOF) magnetic resonance (MR) angiography to develop a protocol for evaluation of peripheral arterial vasculature from the infrarenal aorta to the foot. In the second phase, 73 patients with symptomatic peripheral vascular disease underwent examination with both conventional contrast material-enhanced arteriography and two-dimensional TOF MR angiography to evaluate the clinical usefulness of MR angiography. Postinterventional and intraoperative angiography or direct surgical exploration was the standard of reference. In 32 patients, discrepancies occurred between findings on arteriograms and those on MR angiograms; most of these discrepancies were caused by improved depiction of runoff vessels on MR angiograms. The demonstration with MR angiography of blood vessels not seen on conventional arteriograms, unidentified stenoses, or misidentified blood vessels altered surgical management in 12 patients (16%). Metal-clip artifacts obscured clinically important disease on MR angiograms in two patients. It is concluded that two-dimensional TOF MR angiography is very useful in preoperative assessment of patients with severe peripheral vascular disease.

Nonrigid connectors have been advocated for fixed partial dentures. However, space limitations may require overreduction of the preparation or overcontouring of the retainer to place the keyway within the retainer wall. An inverted orientation of the nonrigid connector can resolve these problems. With this design, the key is attached to the distal surface of the mesial retainer in a dual-abutment fixed partial denture, and the keyway is incorporated in the mesial surface of the pontic. This inverted orientation offers several advantages with few disadvantages.

The objective of this study was to measure marginal fit of castable ceramic versus gold crowns. Full veneer gold and ceramic crowns were made on Ivorine dies. Crowns were cemented, embedded, sectioned faciolingually and mesiodistally, and photographed for measurement of absolute marginal discrepancies (cavosurface angle to casting margin) to evaluate fit. Results revealed no statistically significant differences in fit among four locations around the margins of either ceramic or gold crowns. There was no statistically significant difference in the combined absolute marginal discrepancy (fit) between ceramic and gold crowns. The variance of the combined absolute marginal discrepancy (fit) of the ceramic crowns was significantly different than that of the gold crowns (p = 0.01 level). The standard deviation (variability) of the gold crowns was more than twice that of the ceramic crowns. Randomized block ANOVA demonstrated statistically significant differences among individual gold crown specimens, but none among individual ceramic crown specimens.

Eighteen patients with soft tissue masses underwent integrated magnetic resonance imaging (MRI) and phosphorus spectroscopy (31P-MRS) to evaluate benign and malignant tumor morphology and metabolism. Spectra from soft tissue tumors had a significantly higher proportion of phosphate in the low-energy portion of the 31P spectrum (P less than 0.001) with a concomitant decrease in phosphocreatine (P less than 0.01) compared with 31P spectra from normal muscle. Malignant tumors had a mean pH of 7.35 +/- 0.13 which was greater than that of muscle tissue with a mean pH of 7.08 +/- 0.07 (P less than 0.001). All tumors had greater relative levels of phosphomonoesters, inorganic phosphate, and phosphodiesters compared with those in muscle tissue but considerable variability among tumors was noted due to tumor size, extent of tumor necrosis, and muscle contamination. Integrated MRI/MRS studies are necessary to provide exact localization of the tumor and a more correct interpretation of the 31P-MRS data.

Twenty-three patients with bone and soft tissue tumors were studied with combined magnetic resonance (MR) imaging and spectroscopy. The MR examinations were utilized to determine the size, internal characteristics, and relationships of the tumor to the surrounding tissues. They also determined the optimal placement of the surface coil. The surface coil profile was the localization technique utilized. Four patients were also studied with one-dimensional chemical shift localization. Tumors were grouped according to histologic type, degree of muscle contamination, size, and extent of necrosis. Quantitative comparison among the groups was carried out by comparing the mean ratios of the low-energy phosphate portion of the spectra [phosphomonoester (PME), Pi, phosphodiester (PDE)] to beta-nucleotide triphosphate (NTP). Tumor spectra typically showed a relative elevation in PME, Pi, and PDE and a relative decrease in phosphocreatinine. No characteristic spectra were observed for individual tumor types. Contamination of the tumor spectra from surrounding muscle impaired interpretation of the spectral data. Tumor size and extent of necrosis were important determinants of the relative degree of abnormally elevated metabolite peaks (PME, Pi, PDE). A trend toward a higher mean PME/beta-NTP ratio was observed among high-grade lesions. Combined MR imaging and spectroscopy is a useful way to study tumor metabolism. Muscle contamination is a significant problem in analysis of the spectra. Better localization techniques are required.

We have studied the effects of two diuretics, selective for renal cortical (furosemide) and inner medullary (vasopressin antagonist) water handling, in rat kidney at 1.5 T and find that furosemide completely dissipates the cortical-inner medullary T2 gradient whereas the vasopressin antagonist has little effect. This phenomenon appears to be related to changes in luminal water content. We also demonstrate the feasibility of obtaining live mouse kidney images with a resolution of 100 x 100 x 700 micrometers at 9.4 T.

It is a requirement of many localized NMR spectroscopy experiments, such as DRESS, that collection of the free induction decay be delayed a significant time after the middle of the last pulse. This leads to distortion of the spectra and seriously impedes the retrieval of quantitative information from these spectra. A technique is described in which a correction function is derived from the convoluted spectrum and is used to produce a spectrum with much reduced distortion from which quantitative information may easily be obtained by conventional techniques.

The terminology describing "fit" and the techniques used for measuring fit vary considerably in the literature. Although fit can be most easily defined in terms of "misfit," there are many different locations between a tooth and a restoration where the measurements can be made. In this work, the measurements of misfit at different locations are geometrically related to each other and defined as internal gap, marginal gap, vertical marginal discrepancy, horizontal marginal discrepancy, overextended margin, underextended margin, absolute marginal discrepancy, and seating discrepancy. The significance and difference in magnitude of different locations are presented. The best alternative is perhaps the absolute marginal discrepancy, which would always be the largest measurement of error at the margin and would reflect the total misfit at that point.

A model of radiation injury to the brain was developed in the cat. Definite radiation changes were demonstrated at magnetic resonance (MR) imaging in four of six cats. These changes consisted of high-intensity abnormalities on images obtained with a long repetition time (TR) and a long echo time (TE), which were initially noted 208-285 days after irradiation. These changes were associated with gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) enhancement on short TR and inversion-recovery (IR) pulse sequences. Gd-DTPA enhancement and the high intensity on the long TR/TE images were identified at the same time and became more prominent throughout the study. Chemical-shift imaging and phosphorus spectroscopy demonstrated no notable changes despite clear-cut MR evidence of abnormalities. Sodium imaging was positive in one case. Correlation of MR and pathologic findings revealed areas of radiation necrosis and wallerian degeneration that corresponded to areas of Gd-DTPA enhancement on short TR and IR images and to areas of high intensity on long TR/TE images. Peripheral to the areas of Gd-DTPA enhancement were nonenhanced zones of high-signal-intensity abnormality on long TR/TE images, which represented regions of demyelination without necrosis. Gd-DTPA-enhanced proton imaging was the most sensitive method for detecting radiation damage in this animal model.