Klaus W. Preidler

Functional magnetic resonance imaging of human renal allografts during the post-transplant period: Preliminary observations

Graft dysfunction is a common occurrence during the first weeks following renal transplantation. The current study was designed to evaluate the potential of renal magnetic resonance (MR) perfusion imaging to differentiate acute allograft rejection (AAR) from acute tubular necrosis (ATN) during the post-transplant period. Twenty-three consecutive patients with clinically suspected ATN and/or AAR and eight consecutive control patients (asymptomatic, serum creatinine concentration < 1.5 mg/dL) underwent MR perfusion imaging of the renal allograft within 64 days after transplantation. Histopathology was obtained in all cases with clinical suspicion of ATN or AAR. Sixty sequential fast gradient-recalled-echo MR images were acquired in each patient after intravenous administration of gadolinium-DTPA (0.1 mmol/kg). Histopathology revealed 6 patients with pure AAR, 4 patients with a combination of AAR and ATN, 12 patients with ATN and 1 patient with normal findings. Kidney graft recipients with normal renal function showed a moderate increase in signal intensity (SI) of the renal cortex and medulla after administration of contrast agent followed by an immediate and short decrease in SI of the medulla (biphasic medullary enhancement pattern). The increase in cortical SI of patients with AAR was significantly smaller (61 +/- 4% increase above baseline) than that measured in normal allografts (136 +/- 9% increase above baseline) (p < 0.05) and patients with ATN (129 +/- 3% increase above baseline) (p < .05). Patients with ATN had a slightly delayed and diminished cortical enhancement and an uniphasic and lesser medullary enhancement pattern compared to that observed in normal allografts (p < 0.05). A close correlation (r = 0.72) was found between serum creatinine concentration levels and changes in SI. Thus, MR imaging results and histopathology were in agreement in 22 of 23 patients (96%). MR perfusion imaging of renal allografts can be used to noninvasively differentiate ATN from AAR during the post-transplant period, and may also be helpful in cases were covert AAR is superimposing ATN during a phase of anuria. Patients with ATN can be separated from normals in the majority of cases as reflected by an uniphasic medullary enhancement pattern.

Psoriatic Arthritis and Rheumatoid Arthritis: Findings in Contrast-Enhanced MRI

OBJECTIVE Our objective was to define typical MRI findings of the wrist and the hand in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA). MATERIALS AND METHODS Eighteen PsA and 21 RA patients with arthralgia of the wrist or hand joints underwent gadolinium-enhanced MRI of the wrist and hand. Two experienced radiologists interpreted abnormalities in consensus with respect to periarticular soft-tissue swelling, synovitis with or without effusion, periostitis, bone edema, bone erosions, bone cysts, and tenosynovitis. The distribution of the abnormalities also was evaluated. RESULTS Erosions were statistically more frequent in patients with RA (p < 0.05). Periostitis was statistically seen more frequently in patients with PsA (p < 0.05). No statistically significant difference was found in the frequency of synovitis, bone marrow edema, bone cysts, and tenosynovitis between the two groups (p > 0.05). The radiocarpal joint, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints were significantly affected more frequently in patients with RA than in patients with PsA (p < 0.05), whereas the proximal interphalangeal joints were significantly more frequently affected in patients with PsA (p < 0.05). CONCLUSION Periostitis and synovitis of the proximal interphalangeal joints are typical MRI findings in patients with PsA, whereas synovitis with erosions of the wrist, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints are typical findings in patients with RA.

Distribution Pattern of Computed Tomography Findings in Patients with Bronchiolitis Obliterans Organizing Pneumonia

RATIONALE AND OBJECTIVES The authors evaluated high-resolution computed tomography (HRCT) findings in 15 patients with biopsy-proven bronchiolitis obliterans organizing pneumonia (BOOP). Special attention was paid to lobar distribution to establish a predominant distribution pattern for this disease. SUBJECTS AND METHODS Fifteen patients (average age, 61.8 years) with BOOP underwent computed tomography examinations. The examination technique included a slice thickness of 4 mm with a 4-mm interval; matrix size was 256 x 256 pixels. In all patients, additional HRCT images with a 2-mm slice thickness and a 10-mm interval (matrix, 512 x 512 pixels) were obtained. Interpretation included assessment of pulmonary, pleural, and mediastinal involvement. Special attention was paid to the distribution pattern of pulmonary abnormalities. RESULTS High-resolution computed tomography in all patients demonstrated areas of air space consolidation in a multifocal but peripheral distribution. The right lower lobe was involved in 60% of the patients, the left lower lobe in 53%, the middle and right upper lobes in 20%, and left upper lobe in 23%. Five patients had ground-glass opacities in addition to the areas of air space consolidation, with the incidence in these patients being 100% in the right lower lobe. 80% in the left lower and middle lobes, 60% in the right upper lobe, and 20% in the left upper lobe. Nodules were found in two patients, and the left lower and middle lobes were affected in both. In one patient, the right lower lobe was affected. The interstitium was thickened in 66%, with axial involvement in 20%, septal thickening in 30%, and peripheral regions affected in 50%. Bronchiectasis was present in 60% of all patients studied, predominantly located in the lower lobes. CONCLUSION Bronchiolitis obliterans organizing pneumonia presents a predominant peripheral, bilateral, and nonsegmental distribution, with the lower and middle lobes affected more than the upper lobes.

Diagnostische Wertigkeit von Nativröntgen, Computer- und Magnetresonanztomographie beim akuten Hyperflexionstrauma des FußesEine prospektive klinische Studie

ZusammenfassungUm zufriedenstellende Ergebnisse in der Behandlung von akuten Hyperflexionstraumen des Fußes erzielen zu können, ist eine exakte Primärdiagnostik zwingend erforderlich, da Verletzungen des Tarsometatarsalgelenkes (Lisfranc-Gelenks) bei alleiniger Verwendung konventioneller Röntgendiagnostik häufig übersehen werden. Ziel vorliegender prospektiver Studie war es, die diagnostische Kapazität von Nativröntgen, CT und MRT in der klinischen Anwendung beim akuten Fußtrauma zu vergleichen.Dazu wurden 75 konsekutive Patienten nach akutem Hyperflexionstrauma (Niedrigenergietrauma) des Fußes in die Studie eingeschlossen. Es handelte sich um 47 Männer und 28 Frauen mit einem Durchschnittsalter von 38 Jahren. Es wurden primär a.-p., seitliche und 45°-Schrägaufnahmen sowie Belastungsaufnahmen im Seitenvergleich angefertigt. Des Weiteren wurden eine Computer- und eine Magnetresonanztomographie durchgeführt.Durch die Nativröntgenaufnahmen konnten 48 metatarsale und 24 tarsale Frakturen sowie Störungen des Gelenksalignments bei 17 Patienten festgestellt werden. Die Belastungsaufnahmen erbrachten keine Erweiterung der Diagnose. Computertomographisch wurden 86 metatarsale und 74 tarsale Frakturen, sowie 31 Fälle von Sub- bzw. Luxationen im Lisfranc-Gelenk und 4 knöcherne Avulsionen des Lisfranc-Ligaments diagnostiziert. Die Magnetresonanztomographie konnte 85 metatarsale und 100 tarsale Frakturen, sowie 31 Alignmentstörungen des Lisfranc-Gelenks und 22 komplette oder partielle Rupturen des Lisfranc-Bands diagnostizieren.Die vorliegende Studie zeigte die klare Überlegenheit von Computer- und Magnetresonanztomographie, verglichen mit der konventionellen Röntgendiagnostik in der Evaluation von knöchernen und ligamentären Verletzungen des Lisfranc-Gelenks. Deshalb muss die Forderung nach Durchführung einer erweiterten Diagnostik beim Hyperflexionstrauma des Fußes gestellt werden.AbstractIn order to gain satisfying results in the treatment of acute hyperflexion trauma to the foot, it is absolutely necessary to achieve an exact primary diagnosis because injuries to the tarsometatarsal joint are frequently missed primarily. Aim of this prospective clinical study was to evaluate the diagnostic reliability of conventional radiography, CT and MRI compared to each other.75 consecutive patients after hyperflexion trauma to the foot were included. There were 47 males and 28 females with a mean age of 38 years. After admittance, pa-, lateral and 45° oblique radiographs were taken as well as stress views in comparison to the contralateral foot. Furthermore, CT and MRI were performed in any patient.By conventional radiography, 48 metatarsal and 24 tarsal fractures were diagnosed as well as 17 cases of malalignment of the Lisfranc joint. Stress radiographies were not able to provide a more accurate diagnosis. By CT scans, however, 86 metatarsal and 74 tarsal fractures were detected. Moreover, we found malalignment in 31 and bony avulsions of Lisfrancs ligament in 4 patients. By MRI, finally, 85 metatarsal, 100 tarsal fractures and 31 cases of malalignment were diagnosed. Additionally, partial or complete tears of Lisfrancs ligament were depicted in 22 patients.The present study could clearly show the superiority of CT and MRI to conventional radiography in diagnosis of bony and ligamentous disorders of the Lisfranc joint. Therefore, extended diagnosis has to be demanded in all cases of hyperflexion trauma to the foot.

Echo-enhanced Doppler sonography of focal nodular hyperplasia of the liver.

Lesions of focal nodular hyperplasia are hypervascular, benign focal liver lesions whose differentiation from other focal liver lesions is of significant clinical relevance. The purpose of this study was to investigate the echo‐enhancing agent SHU 508A (Levovist) in the evaluation of focal nodular hyperplasia with Doppler sonography. We examined 49 patients with 71 lesions of focal nodular hyperplasia in the liver with gray scale and power Doppler sonography. In all patients Levovist was administered intravenously in a concentration of 300 to 400 mg galactose per milliliter. Visualization of the feeding vessels and the vascularity of the lesions were evaluated, and the resistive indices in the feeders and the hepatic arteries were assessed. In comparison with unenhanced power Doppler sonography, echo‐enhanced power Doppler sonography yields a higher sensitivity in the detection of the feeding artery (97% versus 82%) in focal nodular hyperplasia and in the depiction of the radial vascular architecture in such lesions, especially those located in the left lobe of the liver. Lesions less than 3 cm in diameter do not consistently show a characteristic vascular architecture with echo‐enhanced Doppler sonography. The resistive index of the tumor‐feeding artery (mean, 0.51 +/‐ 0.09) is significantly (P < 0.0001) lower than that of the hepatic artery (mean, 0.65 +/‐ 0.06) and decreases as the size of the focal nodular hyperplasia increases. The administration of Levovist may improve the signal‐to‐noise ratio and thus visualization of the vascular architecture in focal nodular hyperplasia. Lesions located in the left lobe of the liver, which commonly are subject to disturbing motion artifacts in color Doppler sonography, will significantly benefit from the administration of Levovist. Echo‐enhanced power Doppler sonography, however, is not capable of depicting a characteristic vascular pattern in small (< or = 3 cm) lesions of focal nodular hyperplasia that would guarantee a specific diagnosis.

Routine Use of Three-Dimensional Contrast-Enhanced Moving-Table MR Angiography in Patients with Peripheral Arterial Occlusive Disease: Comparison with Selective Digital Subtraction Angiography

PurposeTo compare the diagnostic accuracy of contrast-enhanced (CE) three-dimensional (3D) moving-table magnetic resonance (MR) angiography with that of selective digital subtraction angiography (DSA) for routine clinical investigation in patients with peripheral arterial occlusive disease.MethodsThirty-eight patients underwent CE 3D moving-table MR angiography of the pelvic and peripheral arteries. A commercially available large-field-of-view adapter and a dedicated peripheral vascular phased-array coil were used. MR angiograms were evaluated for grade of arterial stenosis, diagnostic quality, and presence of artifacts. MR imaging results for each patient were compared with those of selective DSA.ResultsTwo hundred and twenty-six arterial segments in 38 patients were evaluated by both selective DSA and MR angiography. No complications related to MR angiography were observed. There was agreement in stenosis classification in 204 (90.3%) segments; MR angiography overgraded 16 (7%) segments and undergraded 6 (2.7%) segments. Compared with selective DSA, MR angiography provided high sensitivity and specificity and excellent interobserver agreement for detection of severe stenosis (97% and 95%, κ = 0.9 ± 0.03) and moderate stenosis (96.5% and 94.3%, κ = 0.9 ± 0.03).ConclusionCompared with selective DSA, moving-table MR angiography proved to be an accurate, noninvasive method for evaluation of peripheral arterial occlusive disease and may thus serve as an alternative to DSA in clinical routine.

Magnetic resonance imaging of Achilles tendon in patients with rheumatoid arthritis.

RATIONALE AND OBJECTIVES The authors characterize the appearance of the Achilles tendon in patients with rheumatoid arthritis and differentiate this appearance from degenerative tendinopathy in patients with chronic pain of the heel using magnetic resonance (MR) imaging. METHODS Thirty patients with rheumatoid arthritis and 28 patients with chronic pain of the heel underwent MR imaging of the ankle and foot. Three radiologists independently assessed the MR images with respect to size, shape, and intratendinal signal characteristics of the Achilles tendon. The Achilles tendon was considered abnormal on MR imaging when intratendinous signal alterations or an anteroposterior measurement greater than 8 mm was seen. Physical examination of the Achilles tendons was accomplished in both groups. Operation confirmed the diagnosis of 13 patients in the second group with chronic pain of the heel. RESULTS The Achilles tendon of 83% of patients with rheumatoid arthritis demonstrated various intratendinous patterns (longitudinal, reticular, nodular) of intermediate signal intensity on all pulse sequences on MR imaging. Ninety percent of patients with rheumatoid tendinopathy showed no enlargement of the anteroposterior diameter of the Achilles tendon. In addition, all patients with rheumatoid arthritis had findings compatible with an inflammation of the retrocalcaneal bursa on MR imaging, whereas none of the patients with tendinopathy associated with chronic heel pain had retrocalcaneal bursitis. All patients, however, had enlargement of the anteroposterior diameter of the Achilles tendon. Seventy-nine percent showed various intratendinous lesions of intermediate signal intensity on all pulse sequences. Twenty-one percent of patients had an enlargement of the Achilles tendon without intratendinous changes. CONCLUSIONS Rheumatoid tendinopathy can be distinguished from degenerative tendinopathy in patients with chronic pain of the heel with MR imaging. Inflammation of the retrocalcaneal bursa and the absence of enlargement of the tendon combined with the presence of intratendinous signal alterations are characteristic findings of rheumatoid tendinopathy.

Ultrafast Computed Tomography and Three-Dimensional Image Processing of CT Sialography in Patients with Parotid Masses Poorly Defined by Magnetic Resonance Imaging

The purpose of this study was to determine the efficacy of ultrafast computed tomography (UF CT) in patients with parotid masses poorly defined by magnetic resonance imaging (MRI) and to evaluate the diagnostic potential of three-dimensional (3-D) UF CT sialography when compared with conventional CT sialograms. Thirteen patients with clinical suspicion of a parotid mass, in whom MRI was degraded by motion, underwent UF CT of the parotid region. Two radiologists independently assessed the CT and MR with respect to tumor localization, intraglandular tumor location, tumor margin characteristics, and infiltration of surrounding tissue. In 9 patients, CT sialography was performed using 3-D image processing. Anatomical details and pathologic findings were assessed by three readers using a numerical grad and compared with the findings derived from conventional CT sialography. Histopathologic specimens were obtained in all cases and correlated with the radiographic findings in a consensus manner following the blinded interpretations. UF CT and (suboptimal) MRI provided the same diagnostic information for the evaluation of tumor localization, and intraglandular location. UF CT was superior to MRI in the detection of tumor infiltration, and definition of tumor margins in 2 cases (15%), resulting in a substantial difference in treatment. Three-dimensional CT sialography offered significant improvement in demonstration of anatomic detail (2.5 +/- 0.2 vs 1.5 +/- 0.1, respectively) and pathologic findings (2.6 +/- 0.1 vs 1.3 +/- 0.2, respectively) when compared with conventional CT sialography. UF CT is a viable alternative in uncooperative patients with parotid masses. UF CT 3-D sialography has the potential to allow more precise pre-surgical planning and contributes to the diagnosis and therapy planning of parotid masses.

Breast MRI used as a problem-solving tool reliably excludes malignancy

PURPOSE To evaluate the diagnostic performance of breast MRI if used as a problem-solving tool in BI-RADS 0 cases. MATERIAL AND METHODS In this IRB-approved, single-center study, 687 women underwent high-resolution-3D, dynamic contrast-enhanced breast magnetic resonance imaging (MRI) between January 2012 and December 2012. Of these, we analyzed 111 consecutive patients (mean age, 51 ± 12 years; range, 20-83 years) categorized as BI-RADS 0. Breast MRI findings were stratified by clinical presentations, conventional imaging findings, and breast density. MRI results were compared to the reference standard, defined as histopathology or an imaging follow-up of at least 1 year. RESULTS One hundred eleven patients with BI-RADS 0 conventional imaging findings revealed 30 (27%) mammographic masses, 57 (51.4%) mammographic architectural distortions, five (4.5%) mammographic microcalcifications, 17 (15.3%) ultrasound-only findings, and two palpable findings without imaging correlates. There were 15 true-positive, 85 true-negative, 11 false-positive, and zero false-negative breast MRI findings, resulting in a sensitivity, specificity, PPV, and NPV of 100% (15/15), 88.5% (85/96), 57.7% (15/26), and 100% (85/85), respectively. Breast density and reasons for referral had no significant influence on the diagnostic performance of breast MRI (p>0.05). CONCLUSION Breast MRI reliably excludes malignancy in conventional BI-RADS 0 cases resulting in a NPV of 100% (85/85) and a PPV of 57.7% (15/26).

Rate of Malignancy in MRI-Detected Probably Benign (BI-RADS 3) Lesions

OBJECTIVE The purpose of this study was to evaluate the malignancy rate in MRI-detected probably benign (BI-RADS 3) lesions in women without a history of breast cancer. MATERIALS AND METHODS In this study, 1265 patients underwent breast MRI during a 7-year period. One hundred and eight (8.5%) patients with a nonpalpable breast lesion classified as BI-RADS 3 at MRI and with a needle biopsy or adequate follow-up of at least 24 months were included. Statistical analysis included calculation of the negative predictive value with its 95% CI. RESULTS Of 108 lesions, 107 (99.1%) were correctly assessed as probably benign, resulting in a negative predictive value of 99.1% (95% CI, 94.99-99.98%). Histopathology was requested by the patient or referring physician in 44 patients. Of these, 43 (39.8%) lesions were classified as benign and one (0.9%) as malignant. There were no changes evident in any of the remaining 64 (59.2%) lesions during follow-up (range, 2-9 years). CONCLUSION In MRI-detected probably benign (BI-RADS 3) lesions, the malignancy rate is low and within the accepted cancer rate for mammographically or sonographically detected BI-RADS 3 lesions. Short-term follow-up MRI at intervals of 6, 12, and 24 months in MRI BI-RADS 3 lesions remains a strong tool with which to detect suspicious lesions. Interval changes in size, morphology, or enhancement are regarded as indicative of malignancy.