MR urography versus retrograde pyelography/ureteroscopy for the exclusion of upper urinary tract malignancy.

AIM: To evaluate the diagnostic performance of magnetic resonance urography (MRU) versus retrograde pyelography and/or ureteroscopy (RPU) in the detection of upper urinary tract neoplasms. MATERIALS AND METHODS: This retrospective study included 35 patients with suspected upper urinary tract malignancy who underwent MRU and RPU within 6-months in our institution during the study period (February 2002 to January 2007). MRU and RPU reports were reviewed and results recorded. For each patient, the urinary tract was sub-divided into four regions for analysis: left kidney/renal pelvis, left ureter, right kidney/renal pelvis, and right ureter. MRU and RPU results for each patient were compared to a reference standard and the diagnostic performance of both techniques was compared. RESULTS: A total of 113 regions were analysed on MRU and 90 regions on RPU. Nineteen neoplasms were identified. Sensitivity, specificity, positive predictive value, and negative predictive value for the detection of urinary tract neoplasms were 63, 91, 60, and 92% for MRU, respectively, and 53, 97, 83, and 88% for RPU, respectively. These differences were not statistically significant (p>0.05). CONCLUSION: The high negative predictive value of MRU in the present series supports its use as a non-invasive screening examination for excluding the presence of upper urinary tract malignancy.

Surgical repair of type A aortic dissection by the circulatory arrest-graft inclusion technique in sixty-six patients.

During an 8-year period (1984 to 1991) 66 patients (mean age 59 years, range 26 to 84 years) with type A aortic dissection (60 ascending aorta tears, 6 arch tears; 35 acute, 31 chronic) had surgical repair by a continuous suture-graft inclusion technique. Hypothermic circulatory arrest (16 degrees C) was used in 58 patients (35/35 acute, 23/31 chronic; mean arrest time 26 minutes, range 10 to 55 minutes). Fifty-two patients had hemiarch repair and 6 had total arch replacement. Aortic valve disease necessitated treatment in 38 patients (1 valved conduit, 20 valve replacements, 17 valve repairs). Recently 11 patients had valve repair by reconstruction of the native aortic root, by means of techniques similar to those used for homograft valve insertion. Operative mortality was 9% (14% acute, 3% chronic). Stroke occurred in 2 patients (3%) and was fatal in both. Variables suggestive of increased operative risk by univariate analysis were acuteness (p = 0.12), visceral ischemia (p = 0.12), and preoperative shock (p = 0.13). No variable was significant by multivariate analysis. Overall actuarial survival at 48 months was 77%, with 3 late deaths from a ruptured distal aneurysm. Late computed tomography or magnetic resonance imaging scan was done in 28 patients at a mean interval of 33 months. These studies identified 1 patient with a pseudoaneurysm requiring reoperation and 3 patients with contained flow between the graft and the wrap. Three patients required late operation: 1 for pseudoaneurysm, 1 for arch dissection, and 1 for repair of a distal aneurysm.

Use of gadolinium-DTPA-enhanced MRI to characterize renal mass in patient with renal insufficiency.

A patient with chronic renal insufficiency was found to have an indeterminate renal mass after renal ultrasound, non-contrast CT, and non-contrast MRI studies. The mass was correctly diagnosed as an enhancing tumor with gadolinium-DTPA-enhanced magnetic resonance imaging.

Magnetic resonance imaging with magnetic resonance cholangiopancreatography accurately predicts resectability of pancreatic carcinoma.

Accurate preoperative staging of pancreatic malignancy aids in directing appropriate therapy and avoids unnecessary invasive procedures. We evaluated the accuracy of magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) in determining resectability of pancreatic malignancy. Twenty-one patients with suspected pancreatic malignancy underwent dynamic, contrast-enhanced breath-hold MRI with MRCP prior to surgical evaluation. Results of this study were correlated with operative results and pathologic findings. The sensitivity, specificity, and accuracy of MRI with MRCP in detecting a mass, determining the nature of the mass, and predicting lymph node involvement and resectability were determined. MRI with MRCP correctly identified the presence of a pancreatic mass in all 21 of these patients. Following pathologic correlation, it was determined that MRI with MRCP was 81% accurate in determining the benign or malignant nature of the pancreatic mass and 43% accurate in predicting lymph node involvement. In predicting resectability, MRI with MRCP had a sensitivity of 100%, specificity of 83%, positive predictive value of 94%, negative predictive value of 100%, and accuracy of 95%. MRI with MRCP is an accurate, noninvasive technique in the preoperative evaluation of pancreatic malignancy. Information obtained from MRI with MRCP including identification of a mass and predicting tumor resectability may be of value in staging and avoiding unnecessary invasive diagnostic procedures in patients with pancreatic cancer.

Magnetic resonance cholangiopancreatography accurately predicts the presence or absence of choledocholithiasis.

Accurate common bile duct (CBD) imaging in patients with biliary calculi is an important determinant of specific therapy. Noninvasive methods to evaluate calculi in the CBD have limited accuracy and rely mainly on ultrasonography and computed tomography. Magnetic resonance cholangiopancreatography (MRCP) is a new noninvasive modality available to evaluate the biliary system. This study was undertaken to assess the accuracy of MRCP in predicting the presence or absence of CBD stones in patients at increased risk for choledocholithiasis. The medical records of 48 patients with a final diagnosis of biliary calculous disease undergoing MRCP between November 1995 and April 1997 were retrospectively reviewed. Three groups were identified: choledocholithiasis (n = 19), gallstone pancreatitis (n 5 11), and uncomplicated cholelithiasis (n = 18). In all patients the presence or absence of CBD calculi, as determined by MRCP, was correlated with the final diagnosis obtained from endoscopic retrograde cholangiopancreatography (ERCP) (n = 19), intraoperative cholangiography (n = 6), CBD exploration (n = 13), or clinical follow-up (n = 10). Sensitivity, specificity, and accuracy of MRCP were determined. The major clinical indications for MRCP in the 48 patients ware abnormal liver function tests followed by hyperamylasemia. Twenty patients were diagnosed with CBD stones and 28 were not. MRCP correctly predicted the presence of CBD stones in 19 of 20 patients and failed to detect CBD stones in one patient with gallstone pancreatitis. MRCP incorrectly predicted the presence of CBD stones in 3 of 28 patients ultimately found to have gallstones and no CBD stones. MRCP correctly predicted the absence of CBD stones in the other 25 patients including 10 patients with gallstone pancreatitis. Overall, MRCP had a sensitivity of 95%, a specificity of 89%, and an accuracy of 92%. MRCP is an accurate, noninvasive test for evaluating the CBD duct for the presence or absence of calculi in patients suspected of having CBD stones. Our data support the use of MRCP in the preoperative evaluation of these patients as findings may influence therapeutic decisions.

Cystic tumors of the pancreas: the radiologist.

In this article, the author reviews the effect of contemporary imaging techniques on the diagnosis of various pancreatic neoplasms. Histologic detail and the relationship to other means of diagnosis are included.

MR imaging of the pancreas.

Current MR imaging technology offers the surgeon diagnostic information about pancreatic diseases. This article reviews the basics of MR imaging formation and the rationale for the different types of imaging sequences that comprise a comprehensive pancreaticobiliary examination. Clinical examples include evaluation of pancreatic neoplasms, acute and chronic pancreatitis, and congenital abnormalities.

Effect of magnetic resonance exposure combined with gadopentetate dimeglumine on chromosomes in animal specimens.

RATIONALE AND OBJECTIVES: We tested for the presence of a form of unstable chromosomal damage--anaphase bridges--that might result from the combined exposure to gadopentetate dimeglumine and magnetic resonance (MR) imaging in rats. METHODS: Fifty-four male Sprague-Dawley rats, along with appropriate controls, were exposed either to MR imaging alone, gadopentetate dimeglumine alone, or a combination of the two. After exposure, partial hepatectomies were performed to induce a vigorous mitotic response in the regenerating liver stump. Twenty-eight to 30 hr after partial hepatectomy, tissue specimens from regenerating liver were removed and analyzed microscopically for the presence of anaphase bridges. RESULTS: No anaphase bridges were detected in any of the animals, including those exposed to gadopentetate dimeglumine and MR imaging. CONCLUSION: Using anaphase bridge formation as an indicator, exposure to MR imaging alone, gadopentetate dimeglumine alone, or a combination of the two under the conditions used in this experiment did not cause detectable unstable chromosomal damage.

MR angiography of the hand and wrist.

MR angiographic techniques that visualize the arterial anatomy of the hand and wrist currently are available. Further refinements are necessary to ensure that diagnostic studies are routine. In my experience, the most detailed anatomy is obtained with gadolinium-enhanced 3-D sequences. The specific role of MR angiography of the hand and wrist has yet to be defined. Currently, it is used in my practice as a screen for certain vascular disorders and in those patients in whom the risk/benefit considerations of conventional arteriography are deemed unacceptable to the referring surgeon. Future applications may include a quantitative component. This information could prove beneficial in the serial follow up of patients with vasospastic disorders that require intermittent vasodilator therapy. It is hoped that quantitative information might provide a means to direct therapy prior to the onset of debilitating symptoms. Clinical efficacy must be established with comparative studies to the reference standard of conventional angiography. If reliable MR angiography can be obtained with sufficient information for clinical decision making, it is likely that it will have a cost and safety advantage over conventional angiography.

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.

Techniques for liver MR imaging.

MR imaging provides exquisite, versatile, and unique soft tissue contrast, which allows for an effective evaluation of a wide range of liver disorders. A careful selection of imaging strategies can yield a comprehensive assessment of the liver in a reasonable examination time. Recent advances in MR hardware and software allow for rapid acquisition times that can bypass many of the motion artifacts that previously posed limitations to abdominal MR imaging. The ability to obtain artifact-free images with sufficient contrast-to-noise ratios across a broad range of techniques is now feasible with rapid scanning. This capability has emerged as the result of the implementation of high-performance gradient systems and localized phased-array body coils. In this article, the authors review the current status of MR imaging strategies for the evaluation of the liver, with an emphasis on the use of fast scanning techniques.

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.

MR imaging in the evaluation of small (< or =3.0 cm) renal masses.

The use of MR imaging in evaluating renal tumors has expanded beyond the established utility for patients with renal insufficiency and allergy to iodinated contrast. MR imaging is increasingly relied on for the evaluation of small renal lesions. The use of gadolinium chelate contrast agents, high performance MR systems, and optimized techniques is essential. This article details our experience using MR to evaluate small renal tumors and reviews the clinical issues pertinent to the management of these lesions.

Mangafodipir trisodium injection (Mn-DPDP). A contrast agent for abdominal MR imaging.

Mangafodipir trisodium (Mn-DPDP) is one of several recently developed targeted hepatobiliary agents. Contrast-to-noise measurements have shown favorable results for Mn-DPDP-enhanced MR as compared with nonenhanced T1- and T2-weighted images. An improved capability for lesion detection and the ability to characterize tumors of hepatocellular origin have been demonstrated. The prolonged enhancement obtained with Mn-DPDP provides an extended window of time during which effective contrast is maintained as compared with traditional extracellular contrast agents. This report details the experimental and initial clinical experience with Mn-DPDP-enhanced MR imaging of the abdomen.

Volumetric MR imaging of the liver and applications.

Recent improvements in MR technology have enabled the development of volumetric three-dimensional (3D) imaging methods for fat-suppressed T1-weighted images of the entire upper abdomen with pixel sizes of approximately 2 mm in all dimensions and with acquisition times of less than 25 seconds for breath-hold imaging. When performed with a timing scheme, dynamic contrast-enhanced volumetric imaging of the liver can be performed with selective imaging during the arterial phase and portal venous phase of enhancement. The volumetric data sets can be reconstructed in any oblique plane, enabling improved detection, localization, and characterization of small liver lesions. The combination of high-resolution isotropic pixels and accurate timing also permits angiographic reconstructions of the 3D images, producing MR angiography and venography that can be useful in therapeutic planning, such as for catheter-based interventions or surgical resections or transplantation. Additionally, with use of a hepatobiliary contrast agent such as mangafodipir, T1-weighted volumetric MR cholangiography can be performed in patients with nonobstructed systems for depiction of intrahepatic biliary anatomy.

CT and MRI of diffuse liver disease.

CT and MRI contribute important information to the clinical evaluation of diffuse liver disease. In some cases, these modalities can establish a diagnosis that was not ascertained histologically, which is often the case when sampling errors prevent a definitive tissue diagnosis. Characteristic alterations of liver attenuation on CT, signal changes on MRI, and morphological changes appreciated with both modalities can be used to diagnose fatty infiltration, some parenchymal deposition diseases, and cirrhosis. Furthermore, hepatocellular disease can be confirmed in the setting of indeterminate clinical and laboratory findings. Significant overlap in the imaging findings of this wide range of disorders continues to limit specificity; however, at a minimum, these techniques provide a rapid means to a noninvasive evaluation that often guides clinical decisions. Faster scanning techniques available with CT and MRI may provide additional information by assessing contrast dynamics. This review of CT and MRI in diffuse liver disease considers the diagnostic utility and clinical implications of these modalities. Pathological findings relevant to imaging considerations are discussed.

Arteriovenous malformation in a patient with Bannayan--Zonana syndrome.

Bannayan-Zonana syndrome (BZS) is a genetic disorder with autosomal dominant inheritance characterized by macrocephaly and multiple hamartomas of mesodermal origin. Here we present a patient with BZS manifested by many of the classic features, as well as a high-flow upper extremity arteriovenous malformation (AVM). Although this rare syndrome was initially described in 1971, to our knowledge, this is the first report showing an association of AVM with BZS and the first report of this syndrome in the radiologic literature.

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.

Atypical presentation of dissection of the ascending aorta in young men with cystic medial necrosis: MR findings.

Dissection of the ascending aorta is usually associated with severe chest and/or back pain. We describe three young men, with pathologically proven cystic medial necrosis, who presented with atypical clinical symptoms and ascending aortic dissection diagnosed by MR imaging and surgery. Patients with cystic medial necrosis and aortic dissection may not present with a classic acute chest pain syndrome.

Comparison of contrast enhanced CT and Mn-DPDP enhanced MRI for detection of focal hepatic lesions. Initial findings.

Twenty-nine patients with known or suspected focal hepatic disease were evaluated in a retrospective multi-institutional study comparing T1-weighted manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis (phosphate) (DPDP) enhanced magnetic resonance imaging (MRI) with dynamic sequential bolus contrast enhanced computed tomography (DBCT) for the detection of focal liver lesions. The patients were divided into four dose groups, receiving 3, 5, 8, or 10 mumol/kg of Mn-DPDP, delivered either via intravenous bolus (0.25 ml/sec) or infusion (1 ml/sec). Each of three readers, with varying levels of expertise in interpreting hepatic MRI and CT studies, identified more lesions on the Mn-DPDP enhanced MRI than the contrast enhanced CT images. Mn-DPDP enhanced MRI depicted the presence of extensive metastatic disease not seen with DBCT in three patients with fatty liver. The most experienced MRI reader saw more lesions per patient on the Mn-DPDP enhanced MRI than with DBCT, while the opposite held true for the most experienced CT reader. The best single exam for detection of hepatic lesions may be determined by the experience of the reader.