Limited abdominal MRI in the evaluation of acute right upper quadrant pain.

BACKGROUND: We investigated whether limited abdominal magnetic resonance imaging (MRI) is as effective as transabdominal ultrasound (US) in evaluating patients presenting with acute right upper quadrant pain. METHODS: Twenty-four patients underwent evaluation with a limited abdominal MRI using single-shot fast spin-echo sequences and a right upper quadrant US within 24 h. Two MRI and two US readers independently evaluated the images for gallstones, gallbladder wall thickness, pericholecystic fluid, acute cholecystitis, visualization of the common bile duct, and requests for further imaging. US and MRI findings were compared. Surgical pathology was the gold standard. RESULTS: MRI and US demonstrated no statistically significant difference in the diagnosis of gallbladder wall thickening, the presence of gallstones or pericholecystic fluid, or the diagnosis of acute cholecystitis (p > 0.05). The sensitivity of both for acute cholecystitis was 50%, with specificities of 89% and 86% for US and MRI, respectively. US readers more frequently requested additional tests and displayed more variability in whether they could adequately see the common bile duct. CONCLUSION: Limited MRI is equivalent to US in diagnosing gallstones, gallbladder wall thickening, pericholecystic fluid, and acute cholecystitis in patients presenting with symptoms of acute right upper quadrant pain. Especially in sonographically challenging patients, limited MRI may provide a faster, easier method of diagnosis.

Technique for blood conservation in ABIOMED BVS 5000 ventricular assist device exchange.

We describe a technique for blood conservation when ABIOMED BVS 5000 blood pumps require exchange because of thrombus formation in the blood pumps. The technique is simple in concept but requires careful planning and coordination between surgeon and perfusionist.

MRI of the female pelvis.

MRI is a proven modality to evaluate the female pelvis. Excellent soft tissue contrast, sensitivity for the detection of fluid, and the multiplanar imaging capabilities of MR allow noninvasive demonstration of normal anatomy and pathological processes. Most female pelvic MRI studies are performed to answer specific questions and must, therefore, follow carefully developed protocols, which are discussed in this article. The principal MRI techniques and strategies outlined in this work include: (1) the evaluation of reproductive dysfunction, anatomic variants; (2) specific obstetrical applications; (3) oncologic evaluation and tumor staging; (4) problem solving (i.e., the characterization of abnormalities detected by ultrasound); and (5) the evaluation of urethral disease.

Innominate vein cannulation for venous drainage in minimally invasive aortic valve replacement.

Minimally invasive aortic valve or aortic root replacement may be carried out through a mini-hemisternotomy. Venous cannulation of the right atrium may be difficult, at best, and obstruct the limited operative field. We have carried out cannulation of the innominate vein with 25F or 27F thin-walled femoral venous cannulae in 20 patients. Transesophageal echocardiographic guidance is invaluable in safely passing the guidewire and subsequently the cannula into the right atrium. This approach results in an unobtrusive method of complete intrathoracic cannulation through a mini-hemisternotomy with the risks of femoral cannulation.

Renal artery stenosis: evaluation with conventional angiography versus gadolinium-enhanced MR angiography.

PURPOSE: To evaluate the interobserver and intermodality variability of conventional angiography and gadolinium-enhanced magnetic resonance (MR) angiography in the assessment of renal artery stenosis. MATERIALS AND METHODS: Fifty-four patients underwent conventional angiography and gadolinium-enhanced three-dimensional gradient-echo MR angiography. Three angiographers blinded to each other's interpretations and the MR angiographic findings assessed the conventional angiograms for renal artery stenosis. Similarly, three blinded MR imagers evaluated the MR angiograms. RESULTS: Interobserver variability for the degree of renal artery stenosis in the 107 kidneys evaluated was not significantly different between the two modalities. The mean SD of the degree of stenosis was 6.9% at MR angiography versus 7.5% at conventional angiography (alpha < or = .05, P > .05). In 70 kidneys (65%), the average degree of stenosis reported by the readers for the two modalities differed by 10% or less. In 22 cases (21%), the degree of stenosis was overestimated with MR angiography by more than 10% relative to the results of conventional angiography. In 15 cases (14%), the degree of stenosis was underestimated with MR angiography by more than 10%. CONCLUSION: Gadolinium-enhanced MR angiography permits evaluation of renal artery stenosis with an interobserver variability comparable with that of conventional angiography.

Gadolinium-enhanced breathhold three-dimensional time-of-flight renal MR angiography in the evaluation of potential renal donors.

PURPOSE: To evaluate the utility of gadolinium-enhanced three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) of the renal arteries in the evaluation of potential renal donors. MATERIALS AND METHODS: Fifty consecutive patients underwent gadolinium-enhanced 3D-TOF MRA of the renal arteries as part of their evaluation as possible renal donors. All imaging was performed on a 1.5-T system with use of a torso phased-array coil. Conventional T1-weighted axial spin-echo and T2-weighted axial fast spin-echo imaging was performed to evaluate the renal parenchyma. Coronal dynamic MRA was performed during bolus injection of 40 mL of gadolinium with use of a 3D-TOF sequence requiring a breathhold of approximately 30 seconds. Maximum-intensity-projection reconstructions were obtained of the renal arterial and venous anatomy. All studies were prospectively evaluated by a single radiologist experienced with body MRA. Intraoperative findings were used as the reference standard in 35 patients. To evaluate interobserver variability, each examination was evaluated for image quality, renal artery number, and anatomy by two radiologists experienced with MRA and blinded to the other's interpretations and surgical results. RESULTS: Ninety-eight percent of all MRAs were graded as diagnostic quality (Kappa value = 0.38; P < .05). Multiple renal arteries were identified in 29 (29%) of 100 kidneys. Four of 50 patients studied (8%) had renal parenchymal abnormalities identified with MR imaging. Sensitivity and specificity for accessory renal artery detection was 71% and 95%, respectively. Overall, accuracy for MRA in determining renal artery number was 90%. CONCLUSION: Gadolinium-enhanced breathhold 3D-TOF renal MRA is sufficient to assess the renal arteries in potential donors.

MR imaging of the adrenal glands and kidneys.

MR imaging of the adrenal glands and kidneys can completely and accurately assess these organs for a variety of abnormalities. One of the major strengths of MR imaging of the adrenal glands is the ability of chemical shift imaging to determine the presence of intracellular lipid, thus enabling distinction of benign adrenal adenomas from other adrenal masses. The multiplanar imaging capability of MR can assist in determining the origin of large retroperitoneal masses. MR imaging of the kidneys has many applications, including staging of renal cell carcinomas and evaluating the renal vasculature. Gadolinium is a safe and non-nephrotoxic contrast agent that can be used to evaluate the kidneys in patients with renal compromise. The many advances and current research being performed in the rapidly expanding field of abdominal MR make performing these cases both exciting and challenging.

Magnetic resonance imaging of the female pelvis.

Evaluation of pelvic pathology is an important part of most radiology practices. Magnetic resonance imaging (MRI) has proven itself to be a useful and cost-effective method in evaluating many of these diseases. This article reviews appropriate MR imaging techniques and findings of common gynecologic disorders. Uterine pathology is categorized into congenital anomalies, benign lesions (leiomyomas, adenomyosis, endometrial polyps, and nabothian cysts), and malignancies (endometrial and cervical carcinoma). Adnexal pathology reviewed includes endometriosis, polycystic ovaries, teratomas, and benign and malignant ovarian epithelial tumors.

Gadolinium-enhanced ultrafast three-dimensional spoiled gradient-echo MR imaging of the abdominal aorta and visceral and iliac vessels.

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.

Magnetic resonance angiography of the aortic arch.

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.

Breath-hold ultrafast three-dimensional gadolinium-enhanced MR angiography of the aorta and the renal and other visceral abdominal arteries.

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.