Subtraction imaging: applications for nonvascular abdominal MRI.

OBJECTIVE: In this article we will illustrate the role of subtraction imaging for abdominal MRI applications. CONCLUSION: Subtraction imaging has multiple applications for imaging the mediastinum, abdomen, and pelvis. Removing any preexisting signal of T1 unenhanced images causes contrast enhancement within a mass to become more conspicuous on subtracted sequences. This is helpful when evaluating a lesion with high signal on unenhanced T1-weighted sequences, where visual detection of enhancement can be difficult on conventional MRI

Spectrum of CT findings in rupture and impending rupture of abdominal aortic aneurysms.

Prompt diagnosis of rupture and impending rupture of abdominal aortic aneurysms is imperative. The computed tomographic (CT) findings of ruptured abdominal aortic aneurysms are often straightforward. Most ruptures are manifested as a retroperitoneal hematoma accompanied by an abdominal aortic aneurysm. Periaortic blood may extend into the perirenal space, the pararenal space, or both. Intraperitoneal extravasation may be an immediate or a delayed finding. Discontinuity of the aortic wall or a focal gap in otherwise continuous circumferential wall calcifications may point to the location of a rupture. There usually is a delay of several hours between the initial intramural hemorrhage and frank extravasation into the periaortic soft tissues. Contained or impending ruptures are more difficult to identify. A small amount of periaortic blood may be confused with the duodenum, perianeurysmal fibrosis, or adenopathy. Imaging features suggestive of instability or impending rupture include increased aneurysm size, a low thrombus-to-lumen ratio, and hemorrhage into a mural thrombus. A peripheral crescent-shaped area of hyperattenuation within an abdominal aortic aneurysm represents an acute intramural hemorrhage and is another CT sign of impending rupture. Draping of the posterior aspect of an aneurysmal aorta over the vertebrae is associated with a contained rupture

Spontaneous isolated dissection of the celiac artery: CT findings in adults.

OBJECTIVE: Our objective was to describe the CT features of spontaneous isolated celiac artery dissection in a series of six otherwise healthy patients with acute abdominal pain. CONCLUSION: Although once believed rare, isolated spontaneous celiac artery dissection should be considered in the diagnosis of acute abdominal pain, especially in middle-aged adults

Cardiac MRI evaluation of hypertrophic cardiomyopathy: left ventricular outflow tract/aortic valve diameter ratio predicts severity of LVOT obstruction.

PURPOSE: To evaluate if left ventricular outflow tract/aortic valve (LVOT/AO) diameter ratio measured by cardiac magnetic resonance (CMR) imaging is an accurate marker for LVOT obstruction in patients with hypertrophic cardiomyopathy (HCM) compared to Doppler echocardiography. MATERIALS AND METHODS: In all, 92 patients with HCM were divided into three groups based on their resting echocardiographic LVOT pressure gradient (PG):(nonobstructive, n = 31),rest, \u3e30 mmHg after provocation (latent, n = 29), and \u3e30 mmHg at rest (obstructive, n = 32). The end-systolic dimension of the LVOT on 3-chamber steady-state free precession (SSFP) CMR was divided by the end diastolic aortic valve diameter to calculate the LVOT/AO diameter ratio. RESULTS: There were significant differences in the LVOT/AO diameter ratio among the three subgroups (nonobstructive 0.60 ± 0.13, latent 0.41 ± 0.16, obstructive 0.24 ± 0.09, P \u3c 0.001). There was a strong linear inverse correlation between the LVOT/AO diameter ratio and the log of the LVOT pressure gradient (r = -0.84, P \u3c 0.001). For detection of a resting gradient \u3e30 mmHg, the LVOT/AO diameter ratio the area under the receiver operating characteristic (ROC) curve was 0.91 (95% confidence interval [CI] 0.85-0.97). For detection of a resting and/or provoked gradient \u3e30 mmHg, the LVOT/AO diameter ratio area under the ROC curve was 0.90 (95% CI 0.84-0.96). CONCLUSION: The LVOT/AO diameter ratio is an accurate, reproducible, noninvasive, and easy to use CMR marker to assess LVOT pressure gradients in patients with HCM