Multidetector computed tomography arthrography of the shoulder: diagnostic accuracy and indications.

BACKGROUND: The presence of subcutaneous implants, such as permanent defibrillators, is an absolute contraindication to the use of magnetic resonance imaging (MRI). Moreover, MRI is unadvisable in subjects with metallic hardware near the area of study, as artifacts generated by such materials distort image quality. PURPOSE: To evaluate the diagnostic accuracy and indications of arthrography with multidetector computed tomography arthrography (arthro-MDCT) of the shoulder in patients with absolute or relative contraindications to MRI and in patients with periarticular metal implants using diagnostic arthroscopy as the gold standard. MATERIAL AND METHODS: After intraarticular injection of iodixanol and volumetric acquisition, 70 shoulders in 70 patients (30 females, 40 males, age range 32-60 years) were examined with a 16-detector-row CT scanner. The patients had arthralgia but no radiologically detected fractures. They could not be studied by MRI because of absolute contraindications (subcutaneous electronic implants), surgical metal implants, or claustrophobia. In 28 of the 70 patients who had had previous shoulder surgery, the arthro-CT examination was preceded by an MRI on the same day. All examinations were interpreted by two experienced musculoskeletal radiologists. The findings were compared with arthroscopic findings carried out within 28 days of the CT study. RESULTS: In the 42 non-operated patients, the comparison between arthro-MDCT and arthroscopy showed sensitivity and specificity ranging between 87% and 100%. In the 28 operated shoulders, arthro-MDCT had an accuracy of 94% compared with 25% with MRI. Interobserver agreement was almost perfect (kappa=0.95) in the evaluation of all types of lesions, both on MDCT and MRI. When arthro-MDCT was compared with MRI in the postoperative patients by a McNemar test, a significant difference (P<0.05) was found between these two techniques. CONCLUSION: Arthro-MDCT of the shoulder is a safe technique that provides accurate diagnosis in identifying chondral, fibrocartilaginous, and intraarticular ligamentous lesions in patients who cannot be evaluated by MRI, and in patients after surgery.

Congenital anomalies and variations of the bile and pancreatic ducts: magnetic resonance cholangiopancreatography findings, epidemiology and clinical significance.

PURPOSE: The objective of this paper is to document the magnetic resonance cholangiopancreatography (MRCP) findings and the epidemiology of congenital anomalies and variations of the bile and pancreatic ducts and to discuss their clinical significance. MATERIALS AND METHODS: Three-hundred and fifty patients of both sexes (150 females, 200 males, age range 0-76 years, average age 38 years) underwent MRCP for clinically suspected lithiasic, neoplastic or inflammatory disease of the bile and pancreatic ducts. Patients were imaged with a 1.5-T superconductive magnet (Magnetom Vision, Siemens, Erlangen, Germany), a four-channel phased-array body coil, breath-hold technique, with multislice T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE), MIP reconstructions, and a single-shot T2-weighted turbo-spin-echo sequence rapid acquisition with relaxation enhancement (RARE) with different slice thicknesses. Studies in oncological patients were completed with fat saturation 3D T1 gradient-echo sequences during the intravenous injection of gadolinium diethylene triamine pentaacetate acid (DTPA) (0.2 ml/kg). RESULTS: MRCP demonstrated recurrent and therefore normal bile and pancreatic ducts in 57% of patients. In the remaining 42.3%, it documented anatomical variants (41%) and congenital anomalies (1.3%). Variants of the intrahepatic bile duct were seen in 21% of cases: crossover anomaly (6.7%), anterior branch of the right hepatic duct draining the IV and VII segments that flow together with the left bile duct (3.1%) and anterior and posterior branches of the right hepatic duct that flow together with the common hepatic duct (3.3%). Variants of the extrahepatic bile ducts were present in 8.8% of patients: low insertion of the cystic duct into the common hepatic duct (4.5%), emptying of the cystic duct into the right hepatic duct (2.7%) and a second-order large branch draining into the cystic duct (1.6%). MRCP identified a double gall bladder in 3% of patients and anatomical variants of the biliopancreatic system in 8.2%: pancreas divisum (5.2%) and a long sphincter of Oddi (3%). Finally, congenital anomalies were diagnosed in 1.3% of cases: bile duct cysts (0.3%), atresia of the bile ducts (0.3%) and multiple biliary hamartomatosis (0.7%). CONCLUSIONS: The congenital anomalies and anatomical variants of the bile and pancreatic ducts present a complex spectrum of frequent alterations, which are worthy of attention in both the clinical and surgical settings and are readily identified by MRCP.