QCT-based finite element models predict human vertebral strength in vitro significantly better than simulated DEXA.

SUMMARY: While dual energy X-ray absorptiometry (DXA) is considered the gold standard to evaluate fracture risk in vivo, in the present study, the quantitative computed tomography (QCT)-based finite element modeling has been found to provide a quantitative and significantly improved prediction of vertebral strength in vitro. This technique might be used in vivo considering however the much larger doses of radiation needed for QCT. INTRODUCTION: Vertebral fracture is a common medical problem in osteoporotic individuals. Bone mineral density (BMD) is the gold standard measure to evaluate fracture risk in vivo. QCT-based finite element (FE) modeling is an engineering method to predict vertebral strength. The aim of this study was to compare the ability of FE and clinical diagnostic tools to predict vertebral strength in vitro using an improved testing protocol. METHODS: Thirty-seven vertebral sections were scanned with QCT and high resolution peripheral QCT (HR-pQCT). Bone mineral content (BMC), total BMD (tBMD), areal BMD from lateral (aBMD-lat), and anterior-posterior (aBMD-ap) projections were evaluated for both resolutions. Wedge-shaped fractures were then induced in each specimen with a novel testing setup. Nonlinear homogenized FE models (hFE) and linear micro-FE (µFE) were generated from QCT and HR-pQCT images, respectively. For experiments and models, both structural properties (stiffness, ultimate load) and material properties (apparent modulus and strength) were computed and compared. RESULTS: Both hFE and µFE models predicted material properties better than structural ones and predicted strength significantly better than aBMD computed from QCT and HR-pQCT (hFE: R² = 0.79, µFE: R² = 0.88, aBMD-ap: R² = 0.48-0.47, aBMD-lat: R² = 0.41-0.43). Moreover, the hFE provided reasonable quantitative estimations of the experimental mechanical properties without fitting the model parameters. CONCLUSIONS: The QCT-based hFE method provides a quantitative and significantly improved prediction of vertebral strength in vitro when compared to simulated DXA. This superior predictive power needs to be verified for loading conditions that simulate even more the in vivo case for human vertebrae.

Musculoskeletal imaging with a prototype photon-counting detector.

OBJECTIVE: To test a digital imaging X-ray device based on the direct capture of X-ray photons with pixel detectors, which are coupled with photon-counting readout electronics. METHODS: The chip consists of a matrix of 256 × 256 pixels with a pixel pitch of 55 µm. A monolithic image of 11.2 cm × 7 cm was obtained by the consecutive displacement approach. Images of embalmed anatomical specimens of eight human hands were obtained at four different dose levels (skin dose 2.4, 6, 12, 25 µGy) with the new detector, as well as with a flat-panel detector. RESULTS: The overall rating scores for the evaluated anatomical regions ranged from 5.23 at the lowest dose level, 6.32 at approximately 6 µGy, 6.70 at 12 µGy, to 6.99 at the highest dose level with the photon-counting system. The corresponding rating scores for the flat-panel detector were 3.84, 5.39, 6.64, and 7.34. When images obtained at the same dose were compared, the new system outperformed the conventional DR system at the two lowest dose levels. At the higher dose levels, there were no significant differences between the two systems. CONCLUSION: The photon-counting detector has great potential to obtain musculoskeletal images of excellent quality at very low dose levels.

Validation for 2D/3D registration. I: A new gold standard data set.

PURPOSE: In this article, the authors propose a new gold standard data set for the validation of two-dimensional/three-dimensional (2D/3D) and 3D/3D image registration algorithms. METHODS: A gold standard data set was produced using a fresh cadaver pig head with attached fiducial markers. The authors used several imaging modalities common in diagnostic imaging or radiotherapy, which include 64-slice computed tomography (CT), magnetic resonance imaging using T1, T2, and proton density sequences, and cone beam CT imaging data. Radiographic data were acquired using kilovoltage and megavoltage imaging techniques. The image information reflects both anatomy and reliable fiducial marker information and improves over existing data sets by the level of anatomical detail, image data quality, and soft-tissue content. The markers on the 3D and 2D image data were segmented using ANALYZE 10.0 (AnalyzeDirect, Inc., Kansas City, KN) and an in-house software. RESULTS: The projection distance errors and the expected target registration errors over all the image data sets were found to be less than 2.71 and 1.88 mm, respectively. CONCLUSIONS: The gold standard data set, obtained with state-of-the-art imaging technology, has the potential to improve the validation of 2D/3D and 3D/3D registration algorithms for image guided therapy.

[Radiological normal anatomy of the larynx and pharynx and imaging techniques]. / Radiologische Normalanatomie des Larynx und Pharynx sowie bildgebende Techniken.

The larynx and the pharynx represent anatomically as well as functionally a very complex organ which serves as an airway and a nutrition channel. Knowledge of anatomy and anatomical topography is therefore a fundamental basis for the evaluation of any pathological process. Beside the clinical examination and endoscopy performed by ear, nose and throat specialists, imaging techniques play a crucial role in pre-therapeutic and post-therapeutic diagnostics. The radiologist employs a conventional x-ray swallow examination, as well as contrast-enhanced multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), positron emission tomography (PET) and positron emission tomography-computed tomography (PET-CT), depending on the medical problem in question. The following article demonstrates the functional and especially the structural anatomy of the larynx and the pharynx. Furthermore, the broad range of imaging techniques in clinical use is discussed.

Correction to: Analysis and quantification of bone healing after open wedge high tibial osteotomy.

Correction to: Wien Klin Wochenschr 2019 https://doi.org/10.1007/s00508-019-01541-8The original version of this article unfortunately contained a mistake. The presentation of Tab. 4 was incorrect. The corrected table is given below.The original article has been ….

A rare reason for the end of a career in competitive tennis.

Stress fractures are reported in adolescents taking part in high standard sports and they are associated with specific sites for stress fractures. The first rib is also affected in rowers and ball throwing sports. This report describes the complications of such a case in a competitive tennis player at international level practicing 5 times a week with far-reaching consequences. Due to constant load dependent pain in the region of the right shoulder, standard diagnosis, X-ray, magnetic resonance imaging (MRI) and a computed tomography (CT) scan with 3-D reconstruction were done, showing a pseudoarthrosis of the first rib. Therefore, further treatment was conservative without pain relieve. At follow-up 5 years after onset of symptoms the patient did not play tennis, he did not complain pain, but control imaging still showed a pseudoarthrosis of the first rib. Our case shows that it is important, when treating shoulder pain in the overhead athlete, to think of the possibility of a stress fracture.

Validity of sentinel lymph node (SLN) detection following adjuvant radiochemotherapy (RCT) in head and neck squamous cell carcinoma (HNSCC).

The effect of preoperative radio chemotherapy on lymphatic drainage and intraoperative gamma probe-guided sentinel lymph node detection has yet not been investigated. In this study, we study 13 patients with SCC. Sentinel lymph node (SLN) imaging of the patients was performed using SPECT-CT. Special care was taken to use identical injection sites for both studies. Imaging comprised planar and SPECT, iterative reconstruction and were viewed with the co-registered CT image. The results were validated by comparison with the histological results of intraoperative gamma probe detection and histology of the completed neck dissection. Identical SLNs were found in 6/13 patients. In 2/13 cases SLN biopsies were false-negative. In 4/13 patients preoperative SLN imaging identified more/additional nodes than the initial imaging, whereas fewer nodes were seen in 3/13 patients. Neither the primary tumor site nor the TNM stage was predictive for changes in the lymphatic drainage pattern. No constant effect of irradiation could be demonstrated. Preoperative radio chemotherapy has an unpredictable influence on the lymphatic drainage pattern in HNSCC. Consequently, the intraoperative gamma probe-guided sentinel lymph node detection after radio chemotherapy does not reveal the SLN of carcinogenesis. Thus, we advise fused functional/anatomical imaging (SPECT-CT) before and after radiochemotherapy if the SLN concept is utilized in HNSCC.

[Diagnostic imaging in pregraduate integrated curricula]. / Radiologie in einem prägraduellen problembasiert-integrierten Medizincurriculum.

Pregraduate medical curricula are currently undergoing a reform process that is moving away from a traditional discipline-related structure and towards problem-based integrated forms of teaching. Imaging sciences, with their inherently technical advances, are specifically influenced by the effects of paradigm shifts in medical education. The teaching of diagnostic radiology should be based on the definition of three core competencies: in vivo visualization of normal and abnormal morphology and function, diagnostic reasoning, and interventional treatment. On the basis of these goals, adequate teaching methods and e-learning tools should be implemented by focusing on case-based teaching. Teaching materials used in the fields of normal anatomy, pathology, and clinical diagnosis may help diagnostic radiology to play a central role in modern pregraduate curricula.

[Computer assisted radiological diagnostics of arthritic joint alterations]. / Computerassistierte radiologische Diagnostik arthritischer Gelenkveränderungen.

Computer assisted diagnosis (CAD) schemes are currently used in the field of musculoskeletal diseases to quantitatively assess vertebral fractures, joint space narrowing, andr erosion. Most systems work semi-automatically, i.e. they are operator dependent in the selection of anatomical landmarks. Fully automatic programs are currently under development. Some CAD products have already been successfully used in clinical trials.

Dose classification scheme for computed tomography of the paranasal sinuses.

PURPOSE: The purpose of this study was to define objective and reproducible standards for the quality of CT images as a function of radiation doses and therapeutic validity. MATERIALS AND METHODS: CT images of the paranasal sinuses of 145 patients (77 female, 68 male; 5-83 years old; mean age, 39.9 years) were classified both subjectively (with a view toward their validity for the planning of functional endoscopic sinus surgery, FESS) and objectively by defining the pixel noise (the standard deviation, STD, of the CT number) in a homogeneous region of interest (ROI), centered on the M. masseter and on the frontal lobe. These measurements were then compared to measurements obtained from scan images of a water-filled Perspex phantom. RESULTS: The pixel noise measured in the phantom images was nearly identical to the respective values on the M. masseter on the patient images. The use of an edge-enhancing reconstruction algorithm and low-dose protocols, with a pixel noise amounting to 70-90 Hounsfield Units (HU), are indicated for children, chronic sinusitis, and septum deviation, while standard protocols, with a pixel noise of 50-70 HU, are recommended for the preoperative planning and postoperative control of FESS. The pixel noise for high-dose protocols is less than 50 HU; nonetheless, such protocols should generally be avoided. CONCLUSION: The pixel noise measured in a water-filled Perspex phantom is indicative of the clinical potential and image quality of paranasal sinus CT scans. Alternatively, the M. masseter can be chosen as an ROI to measure the pixel noise in order to obtain a rough estimate of the image quality or radiation dose class.

[The role of projectional radiography in the detection of primary malignant and indeterminate bone neoplasms]. / Detektion von primär malignen und intermediären Knochentumoren: Wertigkeit der Projektionsradiographie.

PURPOSE: To evaluate the role of projectional radiography in the detection of primary and potentially malignant bone neoplasms. MATERIALS AND METHODS: We retrospectively reviewed the images and medical records of 80 patients (42 male, 38 female; range: 6 to 73 years; mean: 33 years) with pathologically proven primary or indeterminate bone tumors. RESULTS: The most common symptom was local pain (84 %). In 69 of 80 patients (86 %), projectional radiography was the first imaging modality, which correctly identified the malignant character of the bone lesion in 60 of these 69 patients (87 %). In 2 patients, bone neoplasms were overlooked due to diagnostically inadequte image quality. The false-diagnosis rate was not significantly different between board-certified radiologists working in hospitals and radiologists in outpatient facilities (p > 0.05). Bone tumors predominantly affecting adults, such as chondrosarcomas, needed a longer time for the diagnosis than bone tumors mainly found in childhood, such as osteosarcomas. The median age of patients with delayed imaging work-up because of attempted conservative therapy (45 years +/- 20 years) was significant higher than the median age of patients with immediate radiographic work-up (27 years +/- 16 years). CONCLUSION: Projectional radiography is the most common initial imaging method for bone pain and continues to play an important role to reduce the time gap between first onset of symptoms and definitive treatment. In unremitting focal bone pain, bone neoplasms should be taken into consideration not only in children but also in patients beyond adolescence.

High turnover bone disease following lung transplantation.

Recipients of lung transplants are at very high risk for significant bone loss. Nevertheless, data on bone disease after lung transplantation are still limited. We, therefore, retrospectively evaluated the data of 33 patients surviving at least 1 year after lung transplantation (LTx) who were seen in our outpatient clinic for osteologic evaluation. Results of clinical evaluations, radiographs, and dual-energy X-ray absorptiometry (DXA) were related to each other, to clinical variables, and to serum levels of osteocalcin, parathyroid hormone (PTH), and 25-hydroxyvitamin D: 14 of 33 patients (42%) had vertebral fractures, 9 of whom were diagnosed within 2 years after transplantation. Bone mineral density values (DXA) were markedly decreased and predictive of compression fractures. 25-Hydroxyvitamin D levels were low in 13 patients (39%) and PTH was elevated in 7 (21%). Despite corticosteroids and low 25-hydroxyvitamin D, serum osteocalcin was elevated in 12 patients (36%). This was only partially explained by hyperparathyroidism, low sex hormones, and impaired renal function, and may partly be caused by cyclosporin A. We thus conclude that severe symptomatic bone disease is common in lung transplant recipients and due to a complex situation including high turnover bone loss and hypovitaminosis D. DXA can be used to estimate fracture risk for individual patients.

Technetium-99m-MIBI in primary and recurrent head and neck tumors: contribution of bone SPECT image fusion.

UNLABELLED: We prospectively investigated 200 patients with the clinical suspicion for head and neck tumors. The final diagnoses were 94 primary and 56 (37 confirmed, 19 excluded) recurrent squamous cell carcinomas (SCCs), 3 primary and 7 (4 confirmed, 3 excluded) recurrent adenoid cystic carcinomas (ACCs), 6 non-Hodgkin's lymphomas, 10 distant metastases, 6 other malignancies, 10 inflammatory and 8 other nonmalignant conditions. METHODS: Bone (600 MBq 99mTc-3,3-diphosphono-1,2-propane dicarboxylic acid tetrasodium salt) and hexakis-2-methoxyisobutyl isonitrile (MIBI) (600 MBq 99mTc-MIBI) SPECT were both performed under identical conditions (triple-head gamma camera; ultra-high-resolution, parallel-hole collimators; three-dimensional postfiltering) and judged independently and after superimposition. The results were compared to the results of biopsy, surgery and CT. RESULTS: The overall sensitivity/specificity of MIBI was 90%/78% for tumor detection and 90%/95% for the identification of malignant lymph node involvement (CT: 79%/66%, respectively 90%/79%). In the subgroup of recurrent SCC and ACC the sensitivity/specificity for tumor detection was 95%/71% for MIBI versus 78%/68% for CT. The isolated assessment of bone SPECT had a sensitivity/specificity of 100%/17% for osseous tumor spread. Image fusion of MIBI and bone SPECT differentiated between regio-local bone involvement and inflammatory changes and increased the specificity of bone SPECT to 100% in primary staging. Tumor size, stage, histology and pretreatment had no statistically significant effect on tracer uptake or diagnostic utility of scintigraphy. CONCLUSION: We propose the combined 99mTc-MIBI and bone ultra-high resolution SPECT as a highly useful imaging approach in the primary and secondary staging in patients with suspected malignancies in the head and neck region. The high specificity for malignancies in the head and neck region may be used in the differential diagnosis between head and neck malignancies and inflammatory disease in patients with the accidental finding of enlarged lymph nodes and no clinical signs of a primary tumor. Image fusion with bone scanning is mandatory for the topographical orientation and increases the specificity of bone scanning to differentiate between inflammatory or malignant causes of increased bone metabolism.

Subchondral bone and cartilage disease: a rediscovered functional unit.

The role of subchondral bone in the pathogenesis of cartilage damage has likely been underestimated. Subchondral bone is not only an important shock absorber, but it may also be important for cartilage metabolism. Contrary to many drawings and published reports, the subchondral region is highly vascularized and vulnerable. Its terminal vessels have, in part, direct contact with the deepest hyaline cartilage layer. The perfusion of these vessels accounts for more than 50% of the glucose, oxygen, and water requirements of cartilage. Bony structure, local metabolism, hemodynamics, and vascularization of the subchondral region differ within a single joint and from one joint to another. Owing to these differences, repetitive, chronic overloading or perfusion abnormalities may result in no pathological reaction at all in one joint, while in another joint, these same conditions may lead to osteonecrosis, osteochondritis dissecans, or degenerative changes. According to this common etiological root, similar pathological reactions beginning with marrow edema and necrosis and followed by bone and cartilage fractures, joint deformity, and insufficient healing processes are found in osteonecrosis, osteochondritis dissecans, and degenerative disease as well.

Vascular reconstruction for limb salvage in sarcoma of the lower extremity.

OBJECTIVES: To examine the patency and limb-salvage characteristics of vascular reconstruction in patients with sarcomas of the lower extremity who had been treated with limb-preserving resection and to examine patient survival during a long follow-up period. DESIGN: Retrospective cohort study. SETTING: University hospital, tertiary referral center. PATIENTS: From 1984 to 1992, 14 patients underwent limb-preserving resection of sarcomas in the proximal lower extremity, with 20 vascular reconstructions performed. OUTCOME MEASURES: Color Doppler scans documented patency of the vascular reconstructions. Clinical evaluation included functional results in terms of limb movement and quality of life. Local tumor control and systemic recurrence were examined by repeated radiologic examination. Overall survival as well as time and cause of death were assessed. RESULTS: A total of 13 patients had patent vascular grafts, while the venous graft became occluded in 1 patient. Limb function was rated as excellent or good in 9 patients, as fair in 3, as poor in 1, and could not be clinically estimated in 1. Postoperative thrombosis of the venous graft was detected in 3 patients and was effectively managed by thrombectomy in 2. Three patients underwent reoperation because of hematoma or complications caused by local infection. The tumor endoprosthesis had to be replaced in 3 patients. During follow-up periods that ranged from 15 to 132 months (mean, 55 months), 4 patients died. In all of these patients the cause of death was systemic recurrence in the lung. Two additional patients developed pulmonary metastases, but at the time of this report, they were still alive as long as 132 months after operative resection or chemotherapy. No local recurrence was found. CONCLUSION: Limb-preserving resection of sarcoma of the lower extremity can be performed with satisfactory function of the limb maintained, even if it becomes necessary to resect the femoral vessels. Autologous venous graft for vascular reconstruction is the treatment of choice. In spite of the high incidence of metastases, considerable long-term survival is possible.

Importance of subchondral bone to articular cartilage in health and disease.

The almost absolute barrier to diffusion of nutrients between articular cartilage and subchondral bone does not exist. These anatomic regions represent a functional unit. Repetitive overloading in degenerative disease leads primarily to lesions in the subchondral region (including vessels), which in turn impede flow of nutrition to articular cartilage. As a result, in degenerative joint disease the subchondral region shows reactive enhanced vascularization and heightened metabolism with insufficient repair. In aging, however, vascularization and metabolism are decreased; no repair takes place. In many cases, MRI allows visualization of these subchondral abnormalities. It also demonstrates the basic similarities of degenerative osteoarthritis, osteochondritis dissecans, and avascular necrosis. These different entities may have the same basic etiology but with different disease severity.

Magnetic resonance imaging of the postoperative knee.

Due to the recent development of arthroscopic techniques in meniscal surgery and anterior cruciate ligament reconstruction, an increasing number of postoperative patients are referred for a magnetic resonance examination of the knee because of recurrent injury. Contrary to the nonoperative patient, T2-weighted sequences and, in unequivocal cases, magnetic resonance arthrography play the most important role in the evaluation of a possible meniscal retear. In patients with anterior cruciate ligament reconstruction, the changes of the magnetic resonance appearance of the anterior cruciate ligament graft during the first year after surgery must be considered in the diagnosis of retears. Recent developments in articular cartilage defect repair and the possible role of magnetic resonance imaging in the follow-up are discussed.

A case of aneurysmal bone cyst in father and son.

The authors report a familial case of primary aneurysmal bone cyst in father and son, affecting both at the same location at nearly the same age. This fact again raises the speculation of a genetic link as another factor in the pathogenesis of aneurysmal bone cyst.

Degenerative Achilles tendon disease: assessment by magnetic resonance and ultrasonography.

As Magnetic Resonance (MR) imaging and Ultrasound (US) allow the evaluation of soft-tissue structures not previously possible with other imaging techniques, a clinical study has been undertaken to determine the value of these two modalities in the detection of lesions in the Achilles tendon (AT), other than acute total rupture. Seven healthy subjects and 28 symptomatic patients with Achillodynia and/or signs of thickening of the AT were investigated with MR and US; all results were compared with the clinical features. Surgical findings were available in 14 patients. The patients were divided into three groups; those with tendon thickening, incomplete and complete chronic ruptures. Thickening of the AT was easily detected with both methods. MR was superior in the detection of incomplete tendon rupture and in the evaluation of various stages of chronic degenerative changes. We conclude that only if US remains unclear, an additional MR study should be performed and together with the clinical diagnosis indication for surgery can be made more efficient.

Imaging of tendons--adaptation, degeneration, rupture.

Tendon imaging is mainly performed with ultrasonography (US) and magnetic resonance imaging (MRI) and has been improved within the last years because of technical advancements and a better understanding of tendon pathology. Several concepts concerning the etiology and the course of tendon diseases have influenced image interpretation and vice versa. Adaptive mechanisms within the tendon tissue against stress can be observed mainly on histologic specimens and not macroscopically or with in-vivo imaging. Degeneration may occur in the form of tendinitis, peritendinitis, enthesitis, or myotendinal junction abnormality. Distinct imaging findings exist for most of these forms. Many concepts that have been developed to explain tendon degeneration have been applied on virtually all tendons in the human body. They can be grouped into those which focus on hypovascularization, on biomechanical overload, and on degeneration secondary to other underlying disease. Tendon rupture seems, in many cases, to be the final stage of tendinitis. From this point of view, imaging may be used to predict the risk of tendon rupture together with other intrinsic and with extrinsic parameters. These considerations result in the concept of the "vulnerable zone" and of the "critical phase" in which tendon ruptures may predominantly occur.