Portal vein embolization with use of polyvinyl alcohol particles.

Preoperative portal vein embolization has been used as method of inducing compensatory hypertrophy in the future remnant liver since it was first described in the late 1980s. Many different vascular embolic agents have been successfully used for this procedure, and there is no general consensus regarding which is the best agent. Polyvinyl alcohol (PVA) particles commonly used for arterial embolization come in many sizes, are readily available, and are easy to administer via conventional catheters. We describe an easy, safe, and effective method of the use of PVA particles for portal vein embolization.

T-1 weighted sequences for hepatic MRI: re-evaluation using a phased array coil.

The purpose of this study was to compare three T1-weighted sequences for hepatic magnetic resonance (MRI) imaging with the use of a body phased array coil. Three different T1-weighted MR sequences were compared: a conventional spin echo (CSE); half-Fourier spin echo (HFSE), and a gradient recalled echo (GRE). Three independent reviewers compared the sequences both quantitatively and qualitatively. The T1-weighted GRE sequence scored highest for overall image quality (p < 0.001), lesion conspicuity (p = 0.012), and yielded the highest contrast to noise (C/N) values. GRE T1-weighted images are the best for hepatic MRI.

Echo-train STIR MRI of the liver: comparison of breath-hold and non-breath-hold imaging strategies.

The purpose of this study was to evaluate echo-train short inversion-time inversion recovery (STIR) sequences and compare the results obtained with breath-hold and non-breath-hold imaging strategies. Forty-one patients referred for hepatic magnetic resonance were imaged with both a breath-hold STIR (BH-STIR; acquisition time [TA] 16-20 seconds x 2) and a non-breath-hold STIR (NBH-STIR; TA 210-256 seconds). Quantitative analysis of the liver, spleen, and up to five hepatic lesions per patient was performed. Three blinded readers recorded the number of focal lesions depicted by each study and qualitatively evaluated overall image quality, lesion conspicuity, and image artifacts. The BH-STIR had greater sensitivity (98.8% vs. 91.6%) for detection of hepatic lesions than the NBH-STIR. The BH-STIR was statistically superior in four measures of image quality and had fewer image artifacts. The NBH-STIR images had statistically higher signal-to-noise (S/N, P < 0.001) and liver-lesion contrast-to-noise (C/N, P = 0.005) ratios. For the evaluation of focal hepatic lesions, a breath-hold echo-train STIR sequence provided superior overall image quality and allowed for detection of more lesions in a shorter amount of time than a non-breath-hold echo-train STIR sequence.

Rapid T2-weighted MR imaging of uterine leiomyoma and adenomyosis.

BACKGROUND: To compare three rapid T2-weighted pulse sequences with high-resolution turbo spin-echo (SE) magnetic resonance (MR) imaging for the diagnosis of leiomyoma and adenomyosis. METHODS: Eighteen patients referred for evaluation of suspected leiomyoma or adenomyosis underwent imaging at 1.5 T with a phased-array multicoil. Non-breath-hold, fat-saturated sagittal images of 4-7 mm, with equivalent voxel size, were obtained through the pelvis with the following three rapid pulse sequences: segmented, half-Fourier single shot turbo SE (HASTE), turboGRASE (TGSE) and turbo SE MR images. Mean acquisition times were 17 s (HASTE), 37 s (TGSE), and 42 s (turbo SE). These images were compared, in a blinded fashion, to high resolution turbo SE MR images, which are considered the "standard" for pelvic MRI. RESULTS: The three rapid pulse sequences, HASTE, TGSE and turbo SE, provided equivalent diagnostic information when compared with high-resolution turbo SE MR images. There was no significant difference in image quality, detection and localization of leiomyoma or in diagnosis of adenomyosis among the three rapid sequences. HASTE imaging demonstrated the least ghosting. CONCLUSION: Diagnostic T2-weighted images of benign uterine pathology may be obtained in as little as 17 s.

Suppression of venous signal in time-of-flight MR angiography of the lower extremities after administration of gadopentetate dimeglumine.

PURPOSE: To evaluate a magnetic resonance (MR) angiography time-of-flight technique that can effectively suppress venous signal after gadopentetate dimeglumine administration. MATERIALS AND METHODS: Twelve adult patients underwent MR angiography for the evaluation of peripheral vascular disease. Gradient-echo sequences were performed after the administration of 0.2 mmol/kg gadopentetate dimeglumine. Three sequences were compared: a nontriggered sequence; a gap sequence, an electrocardiographically triggered, segmented sequence with a 7-mm gap between saturation and imaging sections; and a no-gap sequence, a similar sequence as gap but with partially overlapping imaging and saturation sections. For each sequence, identical regions of interest were generated for arterial, venous, and background muscle tissue and noise. A paired Student t test was used to compare the signal-to-noise and contrast-to-noise ratios (C/Ns) among the sequences. In seven patients, the no-gap sequence was used to acquire MR angiograms of the distal lower extremities. RESULTS: The mean artery-muscle C/N was similar for the triggered sequences; both were statistically significantly greater than the ratios for the nontriggered sequence. Venous suppression was much better with the no-gap sequence. Overall, the best artery-vein C/N was also obtained with the no-gap sequence. MR angiograms with effective venous suppression could be obtained only with the no-gap sequence. CONCLUSION: Time-of-flight MR angiograms can be obtained with effective venous suppression after the administration of 0.2 mmol/kg gadopentetate dimeglumine.

Thoracic aorta: comparison of gadolinium-enhanced three-dimensional MR angiography with conventional MR imaging.

PURPOSE: To evaluate gadolinium-enhanced three-dimensional magnetic resonance (MR) angiography for thoracic aortic disease and to compare this technique with conventional thoracic MR imaging. MATERIALS AND METHODS: One hundred eight consecutive patients underwent 122 thoracic MR examinations, including conventional MR imaging followed by enhanced three-dimensional MR angiography. A gradient-echo sequence was used at 1.5 T (116 examinations) and 1.0 T (6 examinations) during infusion of 0.2 mmol/kg gadopentetate dimeglumine. Two independent readers (A and B), with varied experience in thoracic MR angiography, retrospectively evaluated the images for presence of aortic dissection, aneurysm, arch vessel disease, and protruding atheroma. Correlation with findings of surgery or other imaging modalities was available in 98 cases. RESULTS: Enhanced MR angiography was sensitive (92%-96%) and specific (100%) for acute and chronic aortic dissection (n = 26) and was as useful as conventional MR imaging in the diagnosis of aneurysm (n = 43) and arch vessel disease (n = 7). One of two intramural hematomas were overlooked at MR angiography by reader A, and both were overlooked by reader B. CONCLUSION: Enhanced three-dimensional MR angiography is a rapid and accurate imaging modality in diagnosis of thoracic aortic disease but is insensitive to intramural hematoma.

Hepatic arterial-phase dynamic gadolinium-enhanced MR imaging: optimization with a test examination and a power injector.

To optimize findings at dynamic gadolinium-enhanced hepatic magnetic resonance imaging in the hepatic arterial phase, a timing examination was performed after injection of a 0.5-mL timing bolus of gadopentetate dimeglumine. In the experimental group (n = 28), power injection was used and the imaging delay was determined in each patient on the basis of the results of the timing examination. In the control group (n = 28), hand injection and a fixed 20-second imaging delay were used. Arterial-phase examinations (defined as relative liver enhancement of not more than 30% of peak parenchymal enhancement) were successful in 26 (93%) experimental group patients and in 17 (61%) control group patients.

Breath-hold single-dose gadolinium-enhanced three-dimensional MR aortography: usefulness of a timing examination and MR power injector.

PURPOSE: To determine the usefulness of a timing examination performed with 1 mL gadopentetate dimeglumine administered with a magnetic resonance (MR) power injector at single-dose three-dimensional (3D) MR aortography. MATERIALS AND METHODS: 3D fast imaging with steady-state precession (repetition time [msec]/echo time [msec] = 5.0/2.0, with 50 degrees flip angle) was performed in 30 patients after administration of 0.1 mmol/kg gadopentetate dimeglumine. In 15 inpatients, a power injector was used and a timing examination was performed (experimental group). In 15 outpatients, manual injection was used and a timing examination was not performed (control group). In the timing examination, 1 mL gadopentetate dimeglumine was followed with 15 mL saline, both at 2 mL/sec, during axial turbo fast low-angle shot imaging (11/4.2/300 [inversion time ¿msec¿], with a 15 degrees flip angle); one image was obtained every 2 seconds for 60 seconds. Aortic signal-to-noise ratios (S/Ns) and contrast-to-noise ratios (C/Ns) were determined on images obtained in the two groups. RESULTS: In the timing examinations, aortic S/N increased significantly (902% +/- 517 [P < .001]) and was sufficient to help determine the timing of arterial enhancement. Findings on experimental images were superior to those on control images (S/N, 29.8 vs 20.5 [P = .003]; C/N, 23.8 vs 12.8 [P < .001], respectively). The time to perform procedures and calculations at the timing examination added a mean of 4.5 minutes to each examination. CONCLUSION: The combined use of a power injector and a timing examination improved S/Ns and C/Ns at breath-hold single-dose gadolinium-enhanced 3D MR aortography.

Dysplastic nodules and hepatocellular carcinoma: thin-section MR imaging of explanted cirrhotic livers with pathologic correlation.

PURPOSE: To evaluate detection and characterization of hepatocellular nodules in fresh whole explanted cirrhotic livers at thin-section magnetic resonance (MR) imaging. MATERIALS AND METHODS: T1-weighted spin-echo and T2-weighted fast spin-echo MR imaging (5-mm-thick sections) were performed in a head coil at 1.5 T in the whole cirrhotic livers of 28 consecutive patients within 4 hours of explantation. MR imaging findings were correlated with findings at pathologic examination, and new international terminology was used to classify the hepatocellular nodules. RESULTS: At pathologic examination, 42 suspect (other than regenerative) nodules were identified in 11 patients. MR imaging depicted 41 of 42 (98%) of these nodules (five of five hepatocellular carcinomas [HCCs {diameter, > or = 2 cm}], 10 of 10 small HCCs [diameter, < 2 cm], two of two dysplastic nodules with subfoci of HCC, three of three high-grade dysplastic nodules, and 21 of 22 low-grade dysplastic nodules. Lesions demonstrated the following combinations of signal intensity characteristics on thin-section T1- and T2-weighted images, respectively: HCC, hyperintense, hypointense (n = 3); hyperintense, hyperintense (n = 1); hypointense, isointense (n = 1). Small HCC, hyperintense, hypointense (n = 7); hypointense, hyperintense (n = 2); hyperintense, hyperintense (n = 1). Both dysplastic nodules with subfoci of HCC, hyperintense, hypointense. All seven nonsiderotic low-grade dysplastic nodules, hyperintense, hypointense. All 14 siderotic low-grade dysplastic nodules, hypointense, hypointense. All three high-grade dysplastic nodules, hyperintense, hypointense. CONCLUSION: The variable signal intensity characteristics of HCCs made reliable diagnosis impossible, but the thinsection unenhanced in vitro MR images were sensitive for detection of HCCs and dysplastic nodules in cirrhotic livers.

Off-hours interpretation of radiologic images of patients admitted to the emergency department: efficacy of teleradiology.

OBJECTIVE: The purpose of our study was to assess the efficacy of a commercially available digital teleradiology system in the off-site interpretation of radiologic studies performed in the emergency department. MATERIALS AND METHODS: Over a 6-month period, all radiologic studies performed at Roosevelt Hospital between the hours of midnight and 8 A.M. were digitized and then transmitted over a T1 fiberoptic link to the radiology department of St. Luke's Hospital, 4.8 km away. A total of 829 radiologic examinations were performed, 17 of which were lost to follow-up, leaving 812 studies available for review (693 plain radiographs, 118 CT exams, and one MR imaging study). The preliminary teleradiology interpretations were performed by a resident on duty (with between 1 and 3.5 years of training) using a commercially available teleradiology system (Vortech PDS; Kodak Health Imaging Systems Inc., Dallas, TX) at St. Luke's Hospital. This interpretation was compared with the official film interpretation (which was used as the gold standard) performed within 24 hr by a board-certified attending radiologist at Roosevelt Hospital. All studies with clinically significant discrepant interpretations were redigitized, and the digital images were reviewed by at least two attending radiologists. Side-by-side comparison was made with the original analog examinations to determine the source of the discrepancy. Discrepant images were then graded in conjunction with an attending physician from the emergency department to determine the clinical impact on patient management. RESULTS: Clinically significant discrepancies (those with the potential to affect patient management) in image interpretation were found in 38 cases (5% of the total). Of these 38 cases, three cases (0.4%) were due to an inadequate digital image while 14 (2%) were due to interobserver error. Two (0.2%) discrepancies were due to film reader error, and 19 (2%) were due to digital image reader error. Reasons for inadequate digital images included underpenetrated radiographs and drifting of the laser digitizer. CONCLUSION: Commercially available teleradiology equipment can be both reliably and effectively used for off-hours interpretation of radiologic studies made in the emergency department.