Gadolinium-enhanced MR angiography: artifacts and pitfalls.
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Adult↗
Biomedical subjects
N M Rofsky
Publications and source records attributed to N M Rofsky.
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.
Artifacts↗
Single-dose breath-hold gadolinium-enhanced three-dimensional MR angiography of the renal arteries.
PURPOSE: To evaluate the quality of single-dose breath-hold three-dimensional (3D) magnetic resonance (MR) angiography of the renal arteries optimized with a 1-mL test bolus timing examination. MATERIALS AND METHODS: Three-dimensional spoiled gradient-echo imaging (3.8-4.2/1.3-1.7 [repetition time msec/echo time msec], 25 degrees-40 degrees flip angle) was performed in 60 patients after administration of gadopentetate dimeglumine (average dose, 0.11 mmol/kg). Synchronization of contrast material administration with data acquisition was achieved with a 1-mL test dose of contrast material to estimate patient circulation parameters. Image quality was assessed by using contrast-to-noise (CNR), relative vascular enhancement, and venous-to-arterial enhancement ratios and subjective scoring of arterial and venous enhancement. The effect of the contrast material injection rate and the influence of breath holding during the timing examination also were examined. RESULTS: Overall, of 60 studies, 58 were diagnostic and 56 demonstrated excellent arterial enhancement. Venous enhancement was seen in eight studies. The average aortic relative vascular enhancement (+/- SD) was 14.6 +/- 5.9, with an aorta-to-inferior vena cava (IVC) CNR of 69.7 +/- 43.9. The IVC-to-aorta venous-to-arterial enhancement ratio averaged 0.08 +/- 0.16. There was no significant difference in image quality based on injection rates or the performance of breath holding during the timing examination (P > .1). CONCLUSION: Breath-hold gadolinium-enhanced renal MR angiography free of venous enhancement can be performed consistently and reliably with 20 mL of contrast material when studies are synchronized to patient circulation time by using a timing examination.
Contrast Media↗
Abdominal MR imaging with a volumetric interpolated breath-hold examination.
PURPOSE: To compare a T1-weighted, three-dimensional (3D), gradient-echo (GRE) sequence for magnetic resonance (MR) imaging of the body (volumetric interpolated breath-hold examination, or VIBE) with a two-dimensional (2D) GRE breath-hold equivalent. MATERIALS AND METHODS: Twenty consecutive patients underwent 1.5-T MR imaging. The examinations included pre- and postcontrast (20 mL gadopentetate dimeglumine) fat-saturated 2D GRE breath-hold imaging and fat-saturated volumetric interpolated breath-hold imaging before, during (arterial phase), and after injection, with thin (2-mm source images) and thick (8-mm reconstruction images) sections. The three images were compared qualitatively and quantitatively (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]). RESULTS: Qualitatively, the 2-mm source images had poorer pancreatic edge definition on precontrast images compared with the other two data sets (P < .05). On gadolinium-enhanced images, scores for clarity of pancreatic edge, number of vessels visualized, and arterial ghosting were significantly lower for the postcontrast 2D GRE images. Quantitatively, SNR measurements in the liver, aorta, and renal cortex on pre- and postcontrast images were significantly higher for the 8-mm reconstruction images than for the 2D GRE or 2-mm source images (P < .05). Aorta-to-fat CNR was significantly higher on the 8-mm reconstruction images. CONCLUSION: Fat-saturated volumetric interpolated breath-hold images have quality comparable to that of conventional fat-saturated 2D GRE images.
Abdomen↗
Thoracic aorta: rapid black-blood MR imaging with half-Fourier rapid acquisition with relaxation enhancement with or without electrocardiographic triggering.
PURPOSE: To evaluate and compare findings for thoracic aortic disease with three black-blood magnetic resonance (MR) pulse sequences: half-Fourier rapid acquisition with relaxation enhancement (RARE), with and without electrocardiographic (ECG) triggering, and ECG-triggered turbo spin echo (SE). MATERIALS AND METHODS: Axial black-blood MR images of the chest acquired at 1.5 T with a phased-array coil were obtained in 38 consecutive patients referred for evaluation of thoracic aortic disease. ECG-triggered and nontriggered half-Fourier RARE images were compared with T1-weighted ECG-triggered turbo SE images. Two readers independently scored images for each of the following parameters: ghosting artifacts; clarity of the mediastinum, cardiac chambers, and aortic wall; conspicuity of abnormality; intraluminal signal void uniformity; and overall image quality. RESULTS: Both half-Fourier RARE sequences outperformed the turbo SE sequence for all measured parameters. Scores for the ECG-triggered half-Fourier RARE sequence were significantly (P < .05) higher than those for the nontriggered version for clarity of the mediastinum and aortic wall, conspicuity of any abnormality other than aortic dissection, and overall image quality. Mean acquisition times for the ECG-triggered (48 seconds) and nontriggered (30 seconds) sequences were significantly shorter than that for the turbo SE sequence (2 minutes 20 seconds). CONCLUSION: Rapid black-blood half-Fourier RARE sequences, with or without ECG triggering, can replace ECG-triggered turbo SE sequences for evaluation of thoracic aortic disease.
Adult↗
Three-dimensional gadolinium-enhanced MR venographic evaluation of patency of central veins in the thorax: initial experience.
PURPOSE: To assess the usefulness of three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) venography for evaluation of thoracic central veins. MATERIALS AND METHODS: A retrospective study included 15 patients who underwent 3D gadolinium-enhanced subtraction MR venography with a spoiled gradient-echo sequence before and at multiple times after intravenous administration of 30-40 mL of contrast material. Maximum intensity projection and multiplanar reconstruction images were used to categorize central veins as patent, occluded, or narrowed. Results were compared with findings (in 12 patients) at conventional venography (n = 3), attempted central venous catheter placement (n = 3), or surgery (n = 6). Medical records were retrospectively reviewed to determine if patient care was affected by MR venographic findings. RESULTS: By using MR venograms, an appropriate vessel could be identified for successful placement of a catheter, indwelling venous access device, or arteriovenous hemodialysis graft in all nine patients in whom placement was attempted. MR venography also was predictive of unsuccessful hemodialysis catheter placement in one patient. Conventional venographic findings confirmed MR venographic findings in three patients; in a fourth patient, conventional venography was unsuccessful due to inadequate access. MR venographic findings influenced treatment in 14 patients. CONCLUSION: On the basis of these initial results, 3D gadolinium-enhanced MR venography may facilitate comprehensive evaluation of abnormalities of the central veins in the thorax, particularly with regard to selection of venous access sites.
Adult↗
Thoracic aorta: comparison of single-dose breath-hold and double-dose non-breath-hold gadolinium-enhanced three-dimensional MR angiography.
OBJECTIVE: The purpose of this study was to compare single-dose (0.1 mmol/kg) breath-hold gadolinium-enhanced three-dimensional (3D) MR angiography and double-dose (0.2 mmol/kg) non-breath-hold 3D MR angiography for evaluation of thoracic aortic disease. MATERIALS AND METHODS: Twenty-five patients referred for MR evaluation of the thoracic aorta underwent non-breath-hold gadolinium-enhanced 3D MR angiography on a 1.5-T scanner with standard gradients (TR/TE, 21/6; flip angle, 30 degrees) during slow infusion of a double dose of gadopentetate dimeglumine using a body coil. Subsequently, the same patients underwent breath-hold MR imaging with high-performance gradients (TR/TE, 5/2; flip angle, 30 degrees-50 degrees), a timing examination, and power injection of a single dose of gadolinium. For both studies, quantitative signal-to-noise measurements were obtained for the ascending thoracic, descending thoracic, and abdominal aorta. Three observers retrospectively evaluated each examination for degree of enhancement of the aorta, pulmonary arteries, and systemic veins; motion artifacts; and overall image quality. RESULTS: Single-dose breath-hold gadolinium-enhanced 3D MR angiography showed greater signal-to-noise ratio, fewer motion artifacts, and better overall image quality (p < .05) than the non-breath-hold double-dose technique. The single-dose technique also showed significantly better qualitative enhancement of the aortic root and ascending aorta (p < .05) and less enhancement of the pulmonary arteries, renal veins, and left internal jugular vein (p < .05). CONCLUSION: Optimized single-dose breath-hold gadolinium-enhanced 3D MR angiography is superior to double-dose non-breath-hold 3D MR angiography for evaluation of thoracic aortic disease.
Adolescent↗
Improved gadolinium-enhanced subtraction MR angiography of the femoropopliteal arteries: reintroduction of osseous anatomic landmarks.
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Aged↗
Magnetic resonance angiography of the hand. A review.
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Axillary Artery↗
Appendicitis: the impact of computed tomography imaging on negative appendectomy and perforation rates.
OBJECTIVES: The purposes of this study were to investigate the use of computed tomography (CT) imaging in patients with suspected acute appendicitis and to evaluate the impact of CT on negative appendectomy and perforation rates. In patients clinically diagnosed of acute appendicitis the reported overall negative appendectomy rate is about 15-20%; 10% in men and 25-45% in women of childbearing age. This is associated with a perforation rate of 21-23%. METHODS: This is a retrospective analysis of 146 consecutive patients presenting with clinical symptoms suspicious of appendicitis over a 2-yr period in whom CT examinations were performed before therapy was instituted. The overall negative appendectomy and perforation rates were calculated for the entire group, as well as for the 54 women aged 15-50 yr in the childbearing cohort. RESULTS: The negative appendectomy rate was 4% in 122 patients operated on and the perforation rate was 22%. Among 36 women 15-50 yr of age operated on, the negative appendectomy rate was 8.3% and the perforation rate was 19%. Surgery was avoided in 24 patients, 18 of whom were women of childbearing age. CONCLUSIONS: The judicious use of CT imaging in patients with equivocal clinical presentation suspected of having appendicitis led to a significant improvement in the preoperative diagnosis. It resulted in a substantial decrease in the negative appendectomy rate compared to previously published reports, without incurring an increase in the perforation rate.
Acute Disease↗
Gadolinium-enhanced MR angiography of the carotid arteries: a small step, a giant leap?
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Carotid Arteries↗
Dysplastic nodules in cirrhotic liver: arterial phase enhancement at CT and MR imaging--a case report.
In a 65-year-old woman with cirrhosis, biphasic helical computed tomography (CT) and multiphase gadolinium-enhanced magnetic resonance (MR) imaging depicted 11 hepatic nodules that enhanced homogeneously during the hepatic arterial phase. At pathologic examination, all lesions were dysplastic nodules with unpaired hepatic arteries within. Hepatic arterial phase enhancement of cirrhotic nodules at CT and MR imaging is not diagnostic of hepatocellular carcinoma but may occur in dysplastic nodules. Results of a single biopsy yielding hepatocellular carcinoma may not be applicable to other nodules that enhance similarly.
Aged↗
Non-small cell lung carcinoma: usefulness of unenhanced helical CT of the adrenal glands in an unmonitored environment.
PURPOSE: To evaluate routine non-contrast material-enhanced helical computed tomography (CT) of the adrenal glands in patients with non-small cell lung carcinoma to facilitate characterization of adrenal masses detected in an unmonitored environment (i.e., the radiologist on duty did not look at the acquired images before the patient left the scanner). MATERIALS AND METHODS: One hundred consecutive patients with non-small cell lung carcinoma were referred for CT evaluation of the chest; chest and abdomen; or chest, abdomen, and brain. All underwent unenhanced CT of the adrenal glands before the requested CT examination. The morphologic features, size, and attenuation values of the adrenal masses were calculated. Attenuation values of adrenal masses from prior imaging, if available, were compared with those at follow-up imaging to classify these masses. Variable unit cost increase in obtaining these additional images was estimated. RESULTS: Fifteen adrenal masses were identified in 13 patients. In one patient, bilateral ill-defined adrenal masses were present. In 12 patients, 13 masses were sharply circumscribed: Seven were less than 10 HU and six were 20 HU or greater at unenhanced CT. Nine of these 12 patients received iodinated contrast material. Without the unenhanced CT, 10 adrenal masses in these nine patients would have been indeterminate for malignancy. In six of these nine patients, the adrenal mass was the only potential site of metastatic disease. The unenhanced CT data helped classify three of these masses as benign-10 HU or less- and three as indeterminate-greater than 10 HU. CONCLUSION: Unenhanced CT of the adrenal glands can prospectively characterize adrenal masses and obviate further examination in patients with lung carcinoma.
Adrenal Gland Neoplasms↗
MR angiography of the aortic arch vessels and upper extremities.
MR angiography of the aortic arch vessels and upper extremities is a noninvasive alternative to conventional catheter angiography without the risks of stroke or the potential toxicity of iodinated contrast. The use of optimized, breath hold gadolinium-enhanced three-dimensional MR angiography provides excellent image quality with the capability of display options not available with conventional angiography. This article demonstrates the utility of this new technique in the diagnosis of congenital and acquired conditions of the supraaortic vascular system.
Aneurysm↗
MR angiography of the aortoiliac and femoropopliteal vessels.
The variety of MR angiography strategies can be applied to the evaluation of vascular disease in the aortoiliac and femoropopliteal vessels. When used appropriately, a combination of these strategies can be offered to patients with peripheral vascular disease as a safe and effective alternative to conventional angiography for planning treatment options. This article presents the clinical issues, MR techniques, and the results of relevant studies in a detailed manner pertinent to accomplishing diagnostic MR angiography in the aortoiliac and femoropopliteal segments.
Aorta, Abdominal↗
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.
Aged↗
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.
Adolescent↗
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.
Adolescent↗