Three-dimensional gadolinium-enhanced MR angiography of the thoracic aorta.

OBJECTIVE: Our objective was to evaluate image quality and preliminary clinical experience with three-dimensional gadolinium-enhanced MR angiography of the thoracic aorta. SUBJECTS AND METHODS: Ninety patients with suspected thoracic aorta pathology underwent 97 MR examinations at 1.5 T with a 4-min, three-dimensional spoiled gradient-echo techniques. Gadolinium infusion was timed for maximum arterial contrast during acquisition of the central portion of K-space. No ECG gating or breath-holding was used. All MR examinations were evaluated retrospectively for intravascular signal-to-noise ratio (SNR). In 30 of the 90 patients, results from surgery (n = 11), angiography (n = 12), or both (n = 7) were available. Four radiologists who were unaware of the angiographic or surgical findings assessed each of these 30 examinations for three types of pathology: dissection, coarctation, or aneurysm. The observers also assessed aortic branch vessel patency and vascular anomalies in the 19 patients who had angiographic correlation. RESULTS: Image quality (determined as SNR) was highest in the aortic arch, upper descending thoracic aorta, and upper abdominal aorta. We saw a small reduction in the SNR in the ascending aorta and lower descending thoracic aorta (p < .0001), attributable to cardiac and respiratory motion. Image quality was not affected by slow flow. MR imaging correctly diagnosed pathology in all 30 patients with angiographic or surgical correlation, including eight dissections, three coarctations, and 10 aneurysms. The type of the dissection was correctly determined in all eight patients. Stenoses of major branch vessel origins were detected with a sensitivity of 90% (95% bayesian confidence interval, 99-63%) and a specificity of 96% (95% bayesian confidence interval, 99-89%) in the 19 patients with angiographic correlation. Five vascular anomalies, including an aberrant right subclavian artery, a bovine arch, and three accessory renal arteries, were correctly identified. CONCLUSION: Three-dimensional gadolinium-enhanced MR angiography has the potential to accurately diagnose aortic dissection, coarctation, and aneurysm. It does not require ECG gating or breath-holding and thereby extends the diagnostic utility of MR imaging for the thoracic aorta.

Gadolinium-enhanced magnetic resonance angiography of abdominal aortic aneurysms.

PURPOSE: The objective of this study was to assess the usefulness of gadolinum-enhanced magnetic resonance angiography (MRA) for defining anatomic features relevant to performing aortic surgery for aneurysmal disease. METHODS: Anatomic data defined by MRA, including abdominal aortic aneurysm (AAA) size and character, as well as the status of the celiac, mesenteric, renal, and iliac arteries, were correlated with angiography, ultrasonography, computed tomography, or operative data in 43 patients. Five MRA sequences were obtained in an hour-long examination optimized for aortoiliac, splanchnic, and renal artery imaging at 1.5 T in a body coil. Four of the sequences were performed during or after infusion of gadolinium to improve image quality. RESULTS: MRA correctly defined the maximum aneurysm diameter, as well as its proximal and distal extent in all patients. MRA detected 33 of 35 significant stenoses among 153 splanchnic, renal, or iliac branches examined (sensitivity = 94% and specificity = 98%). MRA did not resolve the degree of aortic branch stenotic disease sufficiently to precisely grade its severity. MRA did not reliably define the status of the inferior mesenteric artery, lumbar arteries or internal iliac arteries. One ruptured AAA and one inflammatory AAA were correctly diagnosed by MRA. No patient had a contrast reaction or contrast-induced renal toxicity related to administration of gadolinium. CONCLUSION: Gadolinium-enhanced MRA of AAA provides appropriate, essential anatomic information for aortic reconstructive surgery in a 1-hour examination devoid of contrast-related renal toxicity or catheterization-related complications attending conventional arteriography.

Ovarian vein thrombosis in oncology patients: CT detection and clinical significance.

During a 13-month period, ovarian vein thrombosis (OVT) was detected with CT in six patients with malignant tumors, five of whom were receiving high-dose chemotherapy at the time of diagnosis. None of these patients belonged to previously recognized risk groups. Unlike most patients with postpartum or postoperative OVT, only one of our patients was symptomatic, and none had related CT findings, such as uterine enlargement or other enhancing pelvic masses. Patients with malignant tumors, particularly those undergoing chemotherapy, are at risk for developing OVT. As OVT is often asymptomatic in these patients, and thrombus may resolve without treatment, anticoagulation may not be routinely necessary.

Inhibition and enhancement of skin tumors in mice by dimethyl sulfoxide depending on method of application.

The role of dimethyl sulfoxide [(DMSO) CAS: 67-68-5] in experimental tumorigenesis was investigated because of conflicting reports in the literature ranging from inhibition to no effect to enhancement. With the use of numbers of skin tumors produced on the back of the mouse following topical applications of carcinogenic agents as the variable and with acetone serving as the control solvent, the following results were obtained: When DMSO was the solvent for benzo[a]pyrene (CAS: 50-32-8) in the single-stage model (C3H mice), tumor numbers doubled. When DMSO was the solvent for 7,12-dimethylbenz[a]anthracene (CAS: 57-97-6) serving as initiator in the two-stage model (CD-1 mice), tumor numbers were unaffected. In the two-stage model, when DMSO was the solvent for the potent promoter phorbol-12-myristate-13-acetate [(PMA) CAS: 16561-29-8] or was applied to skin at the initiation site (the back) before PMA, tumor numbers were reduced to one-third of control. However, when DMSO was applied before PMA to the abdomen, a site remote from initiation, tumor numbers doubled. Enhancement of PMA appears to be unique. Recognition that diverse effects can occur depending on the method of application of DMSO may help to decipher the conflicting literature on its relation to tumorigenesis, could be of value in probing the mechanism of tumor promotion, and might signal further caution in its clinical use.

Inhibitory effect of toluene on tumor promotion in mouse skin.

In the two-stage mouse model for skin tumorigenesis with phorbol-12-myristate-13-acetate (PMA) as promoter, topical application of 40 microliters of toluene 2X/week at the initiation/promotion site (the back) reduced the average number of tumors/mouse (ANT/M) to approximately one-fourth that of controls. Control procedure involved initiation of C3H mice with benzo[a]pyrene (BaP) and CD-1 mice with 7,12-dimethylbenz[a]anthracene (DMBA) followed by promotion with from 1 to 5 micrograms PMA in 40 microliters acetone 2X/week. Forty microliters of toluene 2X/week per se was a weak promoter (6-13% of control ANT/M), and produced mild skin irritation at the application site but behavior and body weights were normal. The toluene inhibition of tumorigenesis was not a direct chemical action on PMA since similar effects occurred whether toluene was the vehicle for PMA or whether it was applied up to 1 day before PMA (i.e., prepromotion). Prepromotion with acetone had no effect on tumorigenesis, substantiating its use as control vehicle and suggesting that the toluene inhibition was a specific tissue reaction. The inhibitory effect appeared to be on PMA promotion rather than on initiation since toluene and acetone produced similar numbers of tumors when used as the vehicle for BaP or DMBA in two-stage or BaP in single-stage trials. The inhibition was not permanent since tumorigenesis returned to control rates 2-3 weeks after prepromotion with toluene ceased but promotion with PMA in acetone continued. Toluene may be unique among reported promotion inhibitors in that it is a widely used commercial chemical which sometimes serves as a vehicle in cancer-screening trials. Since its metabolism is reasonably well defined, it may be of value in exploring further the process of tumor promotion.