Klaus Bohndorf

Osteochondritis (osteochondrosis) dissecans: A review and new MRI classification

Abstract. Osteochondritis (osteochondrosis) dissecans (OCD) is a common condition in children, adolescents, and young adults. Describing OCD together with osteochondral fractures and epiphyseal ossification disturbances and considering these three conditions as one entity has caused much confusion. Age distribution and localization combined with the radiologic and surgical presentation distinguishes these conditions. Osteochondritis dissecans represents an osseous lesion with secondary involvement of the overlying cartilage. Beginning as avascular osteonecrosis, OCD forms a transitional zone that harbors the potential of restoration with complete healing or progression to an osseous defect. Mechanical and traumatic factors are etiologically dominant in OCD, but a predisposition seems to be a contributing factor in some patients. Osteochondritis dissecans is generally diagnosed by conventional radiology. Its therapy is determined by the stage of the lesion and MRI will become the method of choice for staging. Intact cartilage, contrast enhancement of the lesion, and absent “cystic” defects are findings of MRI stage I and justify conservative therapy, obviating arthroscopy. Cartilage defect with or without incomplete separation of the fragment, fluid around an undetached fragment, and a dislodged fragment are MRI findings observed in stage II and require arthroscopy with possible intervention. Thus, MRI can noninvasively separate non-surgical from possibly surgical lesions and should replace diagnostic arthroscopy.

Imaging of acute injuries of the articular surfaces (chondral, osteochondral and subchondral fractures)

Abstract Fractures involving the articulating surfaces of bone are a common cause of chronic disability after joint injury. Acute fractures of the articular surface typically run parallel to the surface and are confined to the cartilage and/or the immediate subchondral cancellous bone. They should be distinguished from vertical or oblique bone fractures with intra-articular extension. This article reviews the mechanism of acute articular surface injuries, as well as their incidence, clinical presentation, radiologic appearance and treatment. A classification is presented based on direct inspection (arthroscopy) and imaging (especially MRI), emphasizing the distinction between lesions with intact (subchondral impaction and subchondral bone bruises) and disrupted (chondral, osteochondral lesions) cartilage. Hyaline cartilage, subchondral bone plate and subchondral cancellous bone are to be considered an anatomic unit. Subchondral articular surface lesions, osteochondral fractures and solely chondral fractures are different manifestations of impaction injuries that affect the articulating surface. Of the noninvasive imaging modalities, conventional radiography and MRI provide the most relevant information. The appropriate use of short tau inversion recovery, T1-weighted and T2-weighted (turbo) spin-echo as well as gradient-echo sequences, enables MRI to classify the various acute articular surface lesions with great accuracy and provides therapeutic guidance.

Hoffa's Fat Pad: Evaluation on Unenhanced MR Images as a Measure of Patellofemoral Synovitis in Osteoarthritis

OBJECTIVE The purpose of this study was to compare synovitis-like signal changes in Hoffas fat pad on unenhanced proton density-weighted fat-suppressed sequences with signal alterations in Hoffas fat pad and peripatellar synovial thickening on T1-weighted fat-suppressed contrast-enhanced sequences in patients with osteoarthritis. SUBJECTS AND METHODS Fifty patients with osteoarthritis of the knee participated in the study. MRI was performed with triplanar proton density-weighted fat-suppressed sequences and a sagittal T1-weighted fat-suppressed contrast-enhanced sequence. Signal intensity alterations in Hoffas fat pad were scored semiquantitatively on unenhanced and contrast-enhanced images by two radiologists in consensus. Peripatellar synovial thickness was measured on the T1-weighted fat-suppressed contrast-enhanced images in six locations. Agreement between scoring of signal changes on unenhanced and contrast-enhanced sequences was assessed with kappa statistics. The sensitivity, specificity, and accuracy of scoring of signal-intensity changes on unenhanced images were calculated with T1-weighted contrast-enhanced MRI as the reference standard. In addition, we also examined the relation between signal changes and summed synovial thickness using Spearmans rank correlation coefficient. RESULTS Agreement between unenhanced and contrast-enhanced MRI was fair to moderate (weighted kappa = 0.35 and 0.45). The sensitivity of signal intensity changes in Hoffas fat pad on proton density-weighted fat-suppressed images was high, but specificity was low. Correlations of signal intensity changes in Hoffas fat pad with synovial thickness were lower for unenhanced scans but all were statistically significant. CONCLUSION Signal intensity alterations in Hoffas fat pad on unenhanced images do not always represent synovitis but are a nonspecific albeit sensitive finding. Semiquantitative scoring of synovitis of the patellofemoral region in osteoarthritis ideally should be performed with T1-weighted contrast-enhanced sequences and should include scoring of synovial thickness.

Percutaneous core-needle biopsy of enlarged lymph nodes in the diagnosis and subclassification of malignant lymphomas.

Abstract The objective of this study was to evaluate the sensitivity and specificity of percutaneous core-needle biopsy of enlarged lymph nodes in the diagnosis and subclassification of malignant lymphomas. In a 1-year period 158 image-guided percutaneous core-needle biopsies of enlarged lymph nodes were performed on 149 consecutive patients using a Tru-cut needle fired by a biopsy gun. In 135 cases the biopsy findings could be confirmed by histologic examination of additional tissue samples (n = 59) or by correlation with the patients clinical and radiologic course (n = 76). The final diagnoses were malignant lymphoma in 65 cases, leukemic nodal infiltration in 2, nodal metastases from a solid tumor in 37 and benign changes or no evidence of malignancy in 31 cases. The core-needle biopsies correctly diagnosed 58 of 65 malignant lymphomas, corresponding to a sensitivity of 89 % and a specificity of 97 %. Fifty-five of the 58 (95 %) correctly diagnosed malignant lymphomas could be subclassified on the basis of the core-needle biopsy. Image-guided core-needle biopsy of enlarged lymph nodes with a Tru-cut needle is a useful method for the diagnosis and subclassification of malignant lymphomas.

Traumatic injuries: imaging of peripheral musculoskeletal injuries

Abstract. The current dominant role of conventional radiography must be reassessed at increasingly shorter intervals in view of the continuing emergence of new imaging modalities that are available to diagnose peripheral musculoskeletal injuries. In comparison with conventional radiography, digital radiographic techniques offer advantages for optimization of image quality and dose, such as a wider dynamic range and post-processing of images. Currently, digital luminescence radiography (storage phosphor radiography) is the most commonly used digital method for obtaining radiographs, using the established positioning projections and routines of the film-screen technique. A new process, radiography with flat-panel amorphous silicon detectors, is still under development. Computed tomography is a valuable tool for diagnosing injuries of the peripheral musculoskeletal system, especially when three-dimensional data sets are acquired; these allow reformating images in all planes desired (2D technique) or in a volumetric format (3D technique). Established indications for CT in the peripheral skeleton are hip fractures, wrist injuries and calcaneal fractures; however, CT may be used as a supplement to radiography in every region of the body. Sonography is beginning to play an increasingly important role in trauma. Muscle and tendon injuries are the most common indications, but worthwhile information can be gained of the shoulder, elbow, hip, and knee joints, supplementing conventional or digital radiography. Magnetic resonance imaging effectively visualizes traumatic changes of the skeleton and the peripheral soft tissues. It is the method of choice to detect occult fractures. It can be used to diagnose muscle and tendon injuries. Joint injuries, especially in the knee and the shoulder joint, are common indications for MRI in the posttraumatic setting.

Chronic recurrent multifocal osteomyelitis: a radiological and clinical investigation of five cases

Abstract Objective. To make a detailed evaluation of the clinical and radiological course of five children with chronic recurrent multifocal osteomyelitis (CRMO). Emphasis was laid on the correlation between clinical data and radiological findings. Design and patients. Clinical data, histology (n=11), bone scintigraphy (n=17), and the plain radiographs (n=198) of these patients were reviewed. The mean time of observation was 6.6 years (range 1–14.5 years). Thirty-two lesions seen at the time of primary diagnosis (n=22) or during the course of the disease (n=10) were evaluated. Twenty-seven foci were located in bone; in five cases the sacroiliac joints were involved. Results. Bone scintigrams showed nearly all foci (31/32) and were especially helpful in clinically asymptomatic lesions (14/32) or foci which were radiographically difficult to detect or not seen at all (8/32). Only 14 of 32 foci were locally symptomatic clinically. In all cases with a short interval (≤3 weeks) between the onset of local symptoms and evaluation by plain radiographs (n=5) osteolysis was shown without a sclerotic margin. All bone lesions with a longer duration of local symptoms (n=7) revealed a variable radiographic pattern: osteolysis with sclerotic rim in three, a mixed lytic-sclerotic lesion in three and pure sclerosis in one. In two cases low back pain could be ascribed to sacroiliitis. Conclusion. Only careful correlation between clinical, scintigraphy and radiographic features permits an accurate assessment of disease activity in CRMO. The bone lesions detected radiographically soon after the onset of symptoms resemble those of acute osteomyelitis.

Injuries at the articulating surfaces of bone (chondral, osteochondral, subchondral fractures and osteochondrosis dissecans)

Fractures involving the articulating surfaces of bone are a common cause of joint disability. Management options are as numerous as the terms used to describe these lesions. These terms include osteochondral, transchondral, flake or chip fractures as well as osteochondrosis (osteochondritis) dissecans. The understanding of these traumatic lesions and their sequelae has been increased by modern imaging technology, especially magnetic resonance imaging (MRI). This paper reviews the mechanism of these injuries, their incidence, clinical presentation, radiological appearance and the principles of their treatment. Hyaline cartilage, subchondral bone plate and subchondral cancellous bone have to be seen as an anatomic unity. Subchondrally located cancellous microfractures, osteochondral fractures and solely chondral fractures are different manifestations of impaction injuries at the articulating surfaces. We believe that osteochondrosis dissecans in most cases is also the result of undiagnosed injury at the articulating surface of bone.

Healing Predictors of Stable Juvenile Osteochondritis Dissecans Knee Lesions After 6 and 12 Months of Nonoperative Treatment

Background: Nonoperative treatment of stable juvenile osteochondritis dissecans (JOCD) lesions of the knee fails in up to 50% of cases. Healing predictors are needed to identify potential failures and thus determine treatment options. Purpose: A predictive model for healing potential after 6 and 12 months of nonoperative treatment of stable JOCD lesions based on sensitive magnetic resonance imagining (MRI) follow-up measurements was developed. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A retrospective cross-sectional study was conducted to analyze 62 white patients (76 stable JOCD lesions) who were initially treated by restriction of activity until they were free of pain. The primary end point was healing investigated on MRI with follow-up measurements after 6 and 12 months of nonoperative treatment. Multivariate logistic regression was used to determine the influence of age, sex, JOCD lesion size, clinical symptoms, and the occurrence of cystlike lesions (CLLs) on healing potential. Additionally, optimal prognostic cutoffs were defined to differentiate failures from nonfailures. Results: After 6 months of nonoperative treatment, 51 (67%) of 76 stable JOCD lesions showed no progression toward healing or showed signs of instability. Normalized lesion width and area and CLL occurrence differed significantly between failures and nonfailures (P < .05). A multivariate logistic regression best-predictors model that included age, CLL size, and normalized lesion width best predicted healing after 6 months and resulted in an area under the curve (AUC) of 0.779 (P < .001). A cutoff at 48% healing probability, as predicted by a nomogram based on age, normalized lesion width, and CLL size, differentiated failures from nonfailures (sensitivity, 60.0%; specificity, 83.7%). After 12 months, 37 lesions (49%) had progressed toward healing, and the sole observation of CLL size had the highest predictive validity (AUC, 0.766). The optimal cutoff was a healing probability of 61% (lesion size, 1.3 mm; sensitivity, 70.3%; specificity, 74.1%). Conclusion: A 6-month period of nonoperative treatment with or without casting might be appropriate if the healing potential is >48%. A 12-month period of nonoperative treatment may be successful if the CLL is <1.3 mm in length as assessed on MRI.

MRI, CT, US and ERCP in the evaluation of bile duct hamartomas (von Meyenburg complex): a case report

Abstract. A case of multiple bile duct hamartomas (von Meyenburg complex) of the liver accompanied by exudative and in part necrotizing pancreatitis is presented. Magnetic resonance imaging (fat suppressed, T2-weighted images with prolonged echo time) could exclude diffuse tumor infiltration of the liver, which had not been possible with CT, sonography, or ERCP. To our knowledge, no comparable case has been reported.

Two-dimensional MR angiography in the evaluation of abdominal veins with gradient refocused sequences.

The purpose of this study was to demonstrate the potential role of gradient refocused magnetic resonance imaging as an angiographic method in the evaluation of abdominal veins. Fifteen patients with different venous disorders were examined using first order motion refocused gradient echo sequences (fast low angle shot) in sequential section acquisition technique. Twelve patients had abdominal tumors and three idiopathic thrombosis of abdominal veins. Magnetic resonance was superior to indirect splenoportography and mesentericoportography in evaluation of the abdominal veins in 8 of 10 cases. It was also superior to ultrasound in 3 of 7 cases and to dynamic CT in 2 of 11 cases. This resulted from a higher intrinsic contrast between flowing blood and stationary tissue. It is concluded that two-dimensional gradient refocused imaging may be a valuable angiographic method in the evaluation of abdominal veins.