Acute endometriosis-related sigmoid perforation in pregnancy- case report.

BACKGROUND: An acute abdomen is an emergency that requires accurate diagnosis and prompt treatment. In pregnancy, the process is even more challenging and sometimes the radiological findings are unclear. Moreover, endometriosis- related complications are rare, especially in previously unknown endometriosis. CASE PRESENTATION: We report on a case of acute endometriosis-related sigmoid perforation during pregnancy (34 weeks of gestation) due to a previously unknown deep intestinal infiltrating endometriosis with focal ulceration of the affected colonic mucosa. CONCLUSIONS: Despite the low relative risk, clinicians should be aware of possible endometriosis-associated complications in pregnancy with potentially life-threatening events, even in previously unknown endometriosis. Further studies should evaluate intestinal complications during pregnancy in relation to previous treatment of intestinal endometriosis (conservative vs. surgical).

Systematic analysis of parameters predicting pathological axillary status (ypN0 vs. ypN+) in patients with breast cancer converting from cN+ to ycN0 through primary systemic therapy (PST).

Optimization of axillary staging among patients converting from clinically node-positive disease to clinically node-negative disease through primary systemic therapy is needed. We aimed at developing a nomogram predicting the probability of positive axillary status after chemotherapy based on clinical/pathological parameters. Patients from study arm C of the SENTINA trial were included. Univariable/multivariable analyses were performed for 13 clinical/pathological parameters to predict a positive pathological axillary status after chemotherapy using logistic regression models. Odds ratios and 95%-confidence-intervals were reported. Model performance was assessed by leave-one-out cross-validation. Calculations were performed using the SAS Software (Version 9.4, SAS Institute Inc., Cary, NC, USA). 369 of 553 patients in Arm C were included in multivariable analysis. Stepwise backward variable selection based on a multivariable analysis resulted in a model including estrogen receptor (ER) status (odds ratio (OR) 3.916, 95% confidence interval (CI) 2.318-6.615, p < 0.001), multifocality (OR 2.106, 95% CI 1.203-3.689, p = 0.0092), lymphovascular invasion (OR 9.196, 95% CI 4.734-17.864, p < 0.001), and sonographic tumor diameter after PST (OR 1.034, 95% CI 1.010-1.059, p = 0.0051). When validated, our model demonstrated an accuracy of 70.2% using 0.5 as cut-point. An area under the curve of 0.81 was calculated. The use of individual parameters as predictors of lymph node status after chemotherapy resulted in an inferior accuracy. Our model was able to predict the probability of a positive axillary nodal status with a high accuracy. The use of individual parameters showed reduced predictive performance. Overall, tumor biology was the strongest parameter in our models.

Tissue expanders: early experience of a novel treatment option for perineal herniation.

PURPOSE: Acquired perineal hernias through the reconstructed pelvic floor can complicate radical pelvic operations including abdominoperineal resection of rectum. Operative intervention is indicated for symptomatic hernias. There is a lack of consensus as to the best operative technique. Here we present a novel method for repairing perineal herniation using saline-filled tissue expanders. METHODS: Perineal hernia repair may be affected either via an abdominal or via a perineal approach. After adhesiolysis to remove small bowel from the pelvis, a Natrelle™ 150SH tissue expander (Allergan Inc., California, USA) or Siltex™ Round Becker (Mentor Medical Systems, Holland) of appropriate size is inserted in the pelvis and the button placed in a subcutaneous pocket in the perineal skin. The tissue expander is then filled with saline until it fills the true anatomical pelvis without bladder compression. The volume may be increased or decreased postoperatively by accessing the subcutaneous button. RESULTS: We have performed this procedure in three patients with some success, all of whom have experienced symptomatic relief. The tissue expander may subsequently be removed without recurrence of symptoms, due to the fibrous capsule which forms. One patient required re-operation to elevate a herniating tissue expander. The tissue expander was removed earlier than anticipated to avoid deep pelvic infection in another. CONCLUSION: Our early experience suggests that using saline-filled tissue expanders to fill dead space in the pelvis after radical surgery may prove to be a valuable approach to perineal herniation, particularly if adjuvant radiotherapy is planned.

Relevance and methods of interventional breast sonography in preoperative axillary lymph node staging.

Reduction of therapy-induced morbidity is an important goal for the improvement of the quality of breast cancer treatment. The introduction of sentinel lymph node biopsy (SLNB) significantly contributed to the reduction of surgery-induced morbidity in the shoulder-arm region. However, a clinically positive nodal status is still considered a contra-indication for SLNB. The current data constellation clearly shows that the clinical and also the sonographic malignancy assessment is insufficient for the accurate identification of the nodal status. A merely clinical and/or image-based appraisal of the axillary lymph node status would lead to overtreatment due to unnecessary axillary dissection in approximately 40 % of patients. In order to reduce the rate of unnecessary axillary dissection (AD), pretreatment interventional clarification is necessary to provide more detailed information about the histological condition of the lymph node. Comparing the currently available methods, fine needle aspiration (FNA) is the best in terms of cost and time requirement, practicability and complication rate. However, considering the sensitivity, it is inferior to ultrasound-guided core needle biopsy (CNB). Thus, a negative FNA outcome requires further clarification, which possibly can be performed with CNB. With a specificity of nearly 100 % and therefore a low rate of false positive cases for FNA, complete AD can be indicated by a positive FNA result. In the context of the interventional procedure, it must be stressed that FNA requires a high level of expertise on the part of both the examiner and the cytologist. The prerequisite for optimal interventional diagnostics of lymph nodes is an adequate sonographic assessment on the basis of standardized sonomorphological criteria.

[Performance of a newly developed clip (Tumark Professional) for MRI-guided lesion localization after MRI-guided vacuum-assisted biopsy--first results]. / Einsatz eines speziellen Clips (Tumark Professional) zur postinterventionellen Markierung suspekter Mammaläsionen nach MRT-gestützter Vakuumbiopsie--erste Ergebnisse.

PURPOSE: Evaluation of a newly developed Clip (Tumark Professional) for MRI-guided lesion localization after MRI-guided vacuum-assisted biopsy (VAB) with regard to the exactness of positioning, migration, and visibility on mammography (MG), ultrasound (US) and MR imaging (MRI). MATERIALS AND METHODS: 27 consecutive patients with 29 suspicious breast lesions detected with MRI were prospectively evaluated. The location of the lesion was determined with Tumark (Somatex, Teltow, Germany) after MRI-guided VAB. The distance between the clip and lesion was measured via MRI. The qualitative visibility of the clip was assessed by means of a 5-point scale from very good (1 point) to not visible (5 points). The analysis was performed for MG, US and MRI separately. Clip movement was measured via MG. RESULTS: 9 lesions were malignant (31%). All but one lesion (96%) were able to be localized exactly with a clip-lesion distance of < or = 10 mm. The Tumark was visible in 27 cases (93.1%) in US and in 25 cases (86.2%) in MRI. The visibility of the clip was moderate for both modalities (mean 3.2 points). Its visibility in MG was always very good (1 point). The clip position was stable at the time of short term follow-up (1 - 7 months; mean deviation 4.5 mm). CONCLUSION: Precise positioning of the Tumark Professional is usually possible. The clip is mostly visible in US. At the time of short-term follow-up, there was no relevant movement. Therefore, Tumark seems to be suitable for MRI-guided lesion localization after MRI-guided VAB of suspicious breast lesions. Further improvement of US visibility would be beneficial.

[Mystery of alar ligament rupture: value of MRI in whiplash injuries--biomechanical, anatomical and clinical studies]. / Mysterium Ligamentum alare Ruptur: Stellenwert der MRT-Diagnostik des Schleudertraumas--biomechanische, anatomische und klinische Studien.

PURPOSE: Whiplash injury of the cervical spine is a frequent issue in medical expertise and causes enormous consequential costs for motor insurance companies. Some authors accuse posttraumatic changes of alar ligaments to be causative for consequential disturbances. MATERIALS AND METHODS: Review of recent studies on biomechanics, anatomical and clinical MR imaging. RESULTS: Biomechanical experiments can not induce according injuries of alar ligaments. Although MRI provides excellent visualization of alar ligaments, the range of normal variants is high. CONCLUSION: Biomechanical studies give no evidence of alar ligament involvement in whiplash disease. Using MRI, signal alterations of alar ligaments can hardly be differentiated from common normal variants. Functional MRI provides no diagnostic yield.

Should 3K zoom function be used for detection of pneumothorax in cesium iodide/amorphous silicon flat-panel detector radiographs presented on 1K-matrix soft copies?

The purpose of the study was to evaluate observer performance in the detection of pneumothorax with cesium iodide and amorphous silicon flat-panel detector radiography (CsI/a-Si FDR) presented as 1K and 3K soft-copy images. Forty patients with and 40 patients without pneumothorax diagnosed on previous and subsequent digital storage phosphor radiography (SPR, gold standard) had follow-up chest radiographs with CsI/a-Si FDR. Four observers confirmed or excluded the diagnosis of pneumothorax according to a five-point scale first on the 1K soft-copy image and then with help of 3K zoom function (1K monitor). Receiver operating characteristic (ROC) analysis was performed for each modality (1K and 3K). The area under the curve (AUC) values for each observer were 0.7815, 0.7779, 0.7946 and 0.7066 with 1K-matrix soft copies and 0.8123, 0.7997, 0.8078 and 0.7522 with 3K zoom. Overall detection of pneumothorax was better with 3K zoom. Differences between the two display methods were not statistically significant in 3 of 4 observers (p-values between 0.13 and 0.44; observer 4: p = 0.02). The detection of pneumothorax with 3K zoom is better than with 1K soft copy but not at a statistically significant level. Differences between both display methods may be subtle. Still, our results indicate that 3K zoom should be employed in clinical practice.

[Hereditary motor and sensory neuropathy (HMSN) with hypertrophy of the cauda equina and concomitant demyelinating white matter lesions]. / Hereditäre motorische und sensorische Neuropathie mit Hypertrophie der Cauda equina und demyelinisierenden Läsionen der weissen Substanz.

Hereditary motor and sensory neuropathy (HMSN) is thought to almost exclusively affect the peripheral nervous system. We report the case of a 48-year-old patient with a longstanding history of HMSN type I who developed signs and symptoms of a cauda equina compression and of a central nervous system relapsing-remitting demyelinating white matter disease. Gross enlargement of the cauda equina fibers was detected by MR imaging of the lumbar spine. Cranial MR imaging revealed demyelinating white matter lesions. This case suggests that peripheral neuropathic mechanisms may also affect the central myelin in HMSN type I.

[Estimation of diffuse bone marrow infiltration of the spine in multiple myeloma: correlation of MRT with histological results]. / Beurteilbarkeit diffuser Knochenmarksinfiltrationen der Wirbelsäule bei multiplem Myelom: Korrelation von MRT-Befunden mit der Histologie.

PURPOSE: To determine the detection of diffuse bone marrow infiltration with MRI in comparison with histopathological findings. MATERIALS AND METHODS: MRI was performed on 45 patients with histologically proven multiple myeloma and on 30 healthy individuals. Three experienced radiologists read separately Tl-weighted SE sequences, STIR sequences and the combination of Tl-weighted SE and STIR sequences of the spine. Additionally, Tl-weighted SE sequences were obtained after gadolinium administration and the percentage increase in signal intensity was calculated. Bone marrow histology was used as gold standard for assessing the grade of infiltration. A dichotomous decision (infiltration yes/no) was made when assessing the MRI examinations. RESULTS: For the visual detection of diffuse infiltration, the best sensitivity was found with Tl-weighted SE sequences, achieving 71 % on average. The specificity was 89 %. The STIR sequences showed a sensitivity of 61 % and a specificity of 98 %, and the combination of Tl-weighted/STIR-sequences achieved a sensitivity of 65 % and a specificity of 94 %. In comparison with the histological findings, the sensitivity of the Tl-weighted sequences was 35 % for low-grade, 89 % for moderate and 100 % for high-grade infiltration. The application of contrast material with calculation of the percentage signal increase improved the detection by 7 %. CONCLUSION: The sensitivity of the visual detection of diffuse multiple myeloma with unenhanced MRI is limited for low-grade or moderate infiltration, whereas the sensitivity for high grade infiltration is reliable. The specificity is high and the diagnostic confidence improves after application of contrast material with calculation of the percentage increase in signal intensity.

Diagnosis of adnexal torsion in the third trimester of pregnancy: a case report.

The diagnosis of adnexal torsion is difficult to establish on the basis of symptoms, physical findings, or radiologic techniques. If possible, in pregnancy the diagnostic workup should avoid any risk of drug administration, and the indication for a surgical intervention needs to be severe. Between 10% and 20% of ovarian torsions are associated with pregnancy, but adnexal torsion in the third trimester is rare. We present the case of a 22-year-old female presenting with a sudden onset of severe right lower quadrant abdominal pain associated with nausea and vomiting. The presumptive diagnosis was appendicitis. Transvaginal sonography showed some free fluid in the pouch of Douglas, but could not define the accurate diagnosis. In transabdominal ultrasound, a predominantly hyperechogenic mass containing small cysts was found in the right lower abdomen. No blood flow within the mass was detected with color and power Doppler sonography. With ultrasound, the anatomic relation of the mass could not be precisely identified. Magnetic resonance imaging clearly delineated the mass, which was due to enlargement of the right ovary, with predominately hyperintense signal containing small areas with hypointense lesions in T2-weighted images, a potential sign of hemorrhagic infarction. The mesovarium was hyperintense in T2-weighted images and also enlarged. The left ovary seemed to be normal. Due to the displacement of the ovaries in the second and third trimesters, the diagnostic workup is very largely restricted when using transvaginal ultrasound. Especially in pregnancy, it is mandatory to obtain a reliable diagnosis to reduce any risk to the fetus. Our case report indicates that the combination of magnetic resonance imaging and Doppler sonography fulfills these requirements and allows for accurate and fast diagnosis of adnexal torsion.

MR-imaging changes of musculoskeletal soft-tissue sarcomas associated with neoadjuvant chemotherapy and hyperthermia.

PURPOSE: To evaluate early changes in musculoskeletal soft-tissue sarcomas under neoadjuvant chemotherapy combined with regional hyperthermia (RHT). PATIENTS AND METHODS: Nineteen consecutive patients with high-grade soft-tissue sarcomas of the musculoskeletal system were treated with neoadjuvant chemotherapy combined with RHT. Patients were imaged, using a high field MR-scanner, before onset of therapy, immediately after one and after four cycles of therapy. The images were evaluated for volume reduction and development of tumour necrosis. In addition, side effects such as surrounding soft-tissue oedema, bleeding and muscle or bone marrow necrosis were analysed. RESULTS: Tumour volume reduction was significant after the completion of neoadjuvant therapy (mean 49%, range 5-91%; (p < 0.001). Extent of tumour necrosis was also significantly different before (mean 22%) and after therapy (mean 58%, p < 0.001). Three patients showed strong tumour necrosis already after one cycle of treatment. Tumour volume reduction was not associated with the extent of pre-existing necrosis or necrosis development. The extent of tumour volume before start of therapy did not affect volume reduction or necrosis induction after therapy. Reduction of tumour oedema was significant after therapy (p < 0.001). No side effects were observed during thermochemotherapy. CONCLUSION: Neoadjuvant chemotherapy combined with RHT resulted in significant tumour volume reduction and induction of tumour necrosis, which can be detected early and monitored closely with MRI.

[The roentgenmorphologic aspects of symptomatic calcifications in patients with calcifying tendinitis of the shoulder: determination of intra- and interobserver variabilities of Gärtner's classification]. / Die röntgenmorphologische Gestalt symptomatischer Verkalkungen bei Tendinosis calcarea der Schulter. Bestimmung der Intra- und Interobservervariabilitäten der Klassifikation nach Gärtner.

AIM OF THE STUDY: The roentgenologic morphology of symptomatic calcified deposits of the rotator cuff can be classified according Gärtner. This classification influences therapeutic procedures and prognosis of clinical outcome in these patients. In the present study intraoberserver-reproducibility and interobserver-reliability of Gärtner's classification were tested. METHODS: Plane radiographs of 100 patients with calcifications of the supraspinatus tendon were classified according the criteria of Gärtner by 6 independent observers twice within 4 months. Intraoberserver-reproducibility and interobserver-reliability were calculated by means of Cohen's kappa-index. RESULTS: kappa-values of intraoberserver-reproducibility had a mean of 0.4208 (SD 0.1299), kappa-values of interobserver-reliability were 0.490 for the first and 0.474 for the second classification. CONCLUSIONS: Determination of intraoberserver-reproducibility gave insufficient to satisfactory results, interobserver-reliability was sufficient. The clinical use of Gärtner's classification to plan therapeutic procedures or to determine clinical prognosis in patients with calcifying tendinitis can be recommended only with limitations.

Influence of extracorporeal shock-wave application on normal bone in an animal model in vivo. Scintigraphy, MRI and histopathology.

There is little information about the effects of extracorporeal shock-wave application (ESWA) on normal bone physiology. We have therefore investigated the effects of ESWA on intact distal rabbit femora in vivo. The animals received 1500 shock-wave pulses each of different energy flux densities (EFD) on either the left or right femur or remained untreated. The effects were studied by bone scintigraphy, MRI and histopathological examination. Ten days after ESWA (0.5 mJ/mm2 and 0.9 mJ/mm2 EFD), local blood flow and bone metabolism were decreased, but were increased 28 days after ESWA (0.9 mJ/mm2). One day after ESWA with 0.9 mJ/mm2 EFD but not with 0.5 mJ/mm2, there were signs of soft-tissue oedema, epiperiosteal fluid and bone-marrow oedema on MRI. In addition, deposits of haemosiderin were found epiperiosteally and within the marrow cavity ten days after ESWA. We conclude that ESWA with both 0.5 mJ/mm2 and 0.9 mJ/mm2 EFD affected the normal bone physiology in the distal rabbit femur. Considerable damaging side-effects were observed with 0.9 mJ/mm2 EFD on periosteal soft tissue and tissue within the bone-marrow cavity.

Chest imaging with flat-panel detector at low and standard doses: comparison with storage phosphor technology in normal patients.

The purpose of this study was to evaluate the performance of standard-dose and low-dose cesium iodide (CsI)-doted amorphous silicon (a-Si) flat-panel detector technology (FDT) as compared with storage-phosphor technology (SPT) in the depiction of relevant anatomical structures in chest radiography. In 75 patients referred for thoracic CT, digital chest radiographs were randomly obtained with either SPT at a standard dose (speed class S400, n=25), standard-dose FDT (S400, n=25) or FDT at a low dose (S800, n=25). Five radiologists evaluated the visibility of eight pulmonary and mediastinal anatomical structures using a five-point rating scale. To determine statistically significant differences between the three groups, the Mann-Whitney U-test was employed. No statistically significant differences were found in the depiction of eight criteria between SPT and standard-dose or low-dose FDT chest radiographs. The performance of FDT S400 was equal to SPT for most criteria and better for retrocardiac structures and soft tissue. FDT S800 was inferior to both SPT and FDT S400. Standard-dose FDT is equivalent to SPT in the depiction of relevant anatomical structures of the chest. Our results also indicate that a dose reduction of 50% with FDT may result in small but not significant decrease of image quality.

[Differentiation of benign osteoporotic and neoplastic vertebral compression fractures with a diffusion-weighted, steady-state free precession sequence]. / Differenzierung osteoporotischer und tumoröser Wirbelkörperfrakturen mit einer diffusionsgewichteten steady-state free precession-sequenz.

PURPOSE: To evaluate the diagnostic accuracy of a diffusion-weighted, steady-state free precession (SSFP) sequence for the differentiation of acute benign osteoporotic and neoplastic vertebral compression fractures. METHODS: 85 patients with 102 vertebral compression fractures were examined with MR imaging using a spine array surface coil (Siemens, Vision, 1.5 Tesla). The following sequences were performed in sagittal orientation: T1-weighted spin echo (SE), short-tau inversion recovery (STIR) and a diffusion-weighted SSFP sequence (TR = 25 msec, diffusion pulse length delta = 3 msec). The SSFP images were evaluated qualitatively on a 5-grade scale from strongly hypointense to strongly hyperintense. Quantitative analysis was performed with region of interest measurements (ROI) and calculation of a bone marrow ratio. RESULTS: 60 fractures were due to osteoporosis and 42 fractures were caused by malignancy. "Hyperintensity" in a vertebral fracture on a SSFP sequence provided a sensitivity of 100 % and a specificity of 93 %. The positive predictive value was 91 %, the negative predictive value was 100 %. Quantitative analysis of the bone marrow ratio showed a statistically significant difference between the osteoporosis and the tumor group (p < 0.001). The mean value for the osteoporotic fractures was - 0.32 (SD 0.33) and + 2.07 (SD 1.37) for the tumor group. CONCLUSION: The SSFP sequence provides a high accuracy in the differentiation of benign osteoporotic and neoplastic vertebral compression fractures.

Cervical spine: postmortem assessment of accident injuries--comparison of radiographic, MR imaging, anatomic, and pathologic findings.

PURPOSE: To assess the ability of postmortem radiography and magnetic resonance (MR) imaging to depict occult cervical spine injuries as compared with anatomic and pathologic findings. MATERIALS AND METHODS: The cervical spines of 10 adult accident victims underwent radiography and MR imaging, with T1-weighted, fast spin-echo T2-weighted, and four gradient-echo pulse sequences. The frozen specimens were cut into 3-mm-thick slices (sagittal plane) and photographed, and microfocus radiographs were obtained. Imaging findings were compared with the anatomic and pathologic findings. RESULTS: Eight of the 10 specimens had 28 posttraumatic lesions: three fractures (two missed at the initial MR imaging reading), 10 facet joint capsule lesions with bleeding, five soft-tissue and ligament lesions, eight disk lesions, and two spinal cord lesions. Radiography depicted one lesion (4%). Two partial ruptures of the anterior annulus fibrosus were depicted at only MR imaging. Initially, 11 of 28 lesions were detected on MR images; retrospectively, 17 of 28 lesions were correlated with anatomic findings. CONCLUSION: Soft-tissue and intervertebral disk and ligament injuries account for 89% (25 of 28) of posttraumatic cervical spine lesions detected on postmortem images. Occult lesions, including apophyseal joint injuries, were found in clinically noninjured cervical spines. MR imaging was limited in the depiction of discrete lesions when T1-weighted non-fat-saturated, fast spin-echo T2-weighted, and gradient-echo pulse sequences were used.

Case-oriented computer-based-training in radiology: concept, implementation and evaluation.

BACKGROUND: Providing high-quality clinical cases is important for teaching radiology. We developed, implemented and evaluated a program for a university hospital to support this task. METHODS: The system was built with Intranet technology and connected to the Picture Archiving and Communications System (PACS). It contains cases for every user group from students to attendants and is structured according to the ACR-code (American College of Radiology) 2. Each department member was given an individual account, could gather his teaching cases and put the completed cases into the common database. RESULTS: During 18 months 583 cases containing 4136 images involving all radiological techniques were compiled and 350 cases put into the common case repository. Workflow integration as well as individual interest influenced the personal efforts to participate but an increasing number of cases and minor modifications of the program improved user acceptance continuously. 101 students went through an evaluation which showed a high level of acceptance and a special interest in elaborate documentation. CONCLUSION: Electronic access to reference cases for all department members anytime anywhere is feasible. Critical success factors are workflow integration, reliability, efficient retrieval strategies and incentives for case authoring.

Assessment of the position of the distal portion of the ulna in lateral projection radiographs of the wrist: analysis of the influence of pronation-supination and flexion-extension on the pisoscaphoid and the ulnotriquetral distances: a cadaver study.

RATIONALE AND OBJECTIVES: Accurate assessment of the distal radioulnar joint is of paramount importance for the detection of possible dislocation or subluxation. Using a cadaveric model, the authors attempted to establish a quantitative method that would allow identification of normal and abnormal distal radioulnar joint anatomy on well-positioned and rotated conventional radiographs. METHODS: Four cadaveric wrists, in which subsequent sectioning confirmed the absence of disease, and one cadaveric wrist with a circumscribed lesion of the triangular fibrocartilaginous complex were studied. Defined movements in flexion and extension (+/- 10 degrees, 20 degrees, 30 degrees ) and in pronation and supination (+/- 10 degrees, 20 degrees, 30 degrees ) as well as combined flexion/extension and pronation/supination were performed. The ulnotriquetral and the pisoscaphoid distances were assessed in each position. Correlation with cryosections was achieved. RESULTS: A strong linear correlation between the degree of pronation or supination and the pisoscaphoid and ulnotriquetral distances was noted. Flexion and extension produced no significant effect on the pisoscaphoid distance, but a defined shift of the ulnotriquetral distance occurred with increasing flexion and extension. CONCLUSIONS: If all parameters are taken into account, this correlation aids in estimating the degree of possible malpositioning of the wrist during radiography and the degree of subluxation of the distal radioulnar joint. Tabular data with parameters to correct for instances of malrotated images and to estimate the extent of dislocation or malrotation of the distal radioulnar joint are provided.

[Benign bone-forming tumors]. / Gutartige knochenbildende Tumoren.

Benign bone-forming tumors include osteomas, enostomas, osteoid osteomas, and osteoblastomas. These lesions are often characterized by typical imaging findings on radiographs, CT and MR imaging studies. Radiologic findings and additional clinical information allow for a specific diagnosis in most cases. This review article emphasizes the radiological patterns of benign bone-forming tumors as well as their epidemiological, clinical, and pathological characteristics. In addition, minimally invasive interventional procedures for the therapy of osteoid osteoma are reviewed.