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Abstract: This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. Other conditions which affect bone turnover include osteomalacia, hyperparathyroidism, chronic renal failure and high-dose glucocorticoid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures, and to differentiate them from other bone lesions. Radiographs are still the most widely used imaging method for identification of insufficiency fractures, but sensitivity is limited, depending on the location of the fractures. Magnetic resonance imaging (MRI) is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures. Thin section, multi-detector computed tomography (MDCT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures. [Copyright &y& Elsevier]

Rationale and Objectives: We sought to evaluate the diagnostic performance of high-resolution magnetic resonance imaging (MRI) and conventional MRI of the knee on a standard–field-strength MRI system compared to arthroscopic findings in patients with suspected meniscal tears. Materials and Methods: Forty-two patients (20 women, 22 men), referred from the department of trauma surgery, with suspected medial meniscal tears and planned arthroscopy of the knee joint were included in the study. MRI was performed on a 1.0-T MRI scanner with two different protocols: (1) conventional MRI using a circular, polarized knee coil (coil diameter: 17 cm) with a sagittal dual fast spin-echo sequence (repetition time [TR]: 2500 ms; echo time [TE]: first, shortest, second, 120 ms; turbo spin echo [TSE] factor: 12; field of view: 180 mm; matrix: 256 × 512; scan percentage: 100; slice thickness: 3 mm) or (2) high-resolution MRI with a surface dual-loop coil of the medial knee compartment (temporomandibular joint, coil diameter: 8 cm) with a sagittal dual fast spin-echo sequence (TR: 2400 ms; TE: first, shortest; second, 120 ms; TSE factor: 12; field of view: 120 mm; matrix: 512 × 512; slice thickness: 2 mm). The menisci were evaluated on the basis of an adapted score (0 = normal meniscus, 1 = intrameniscal, T2-weighted hyperintense signal, 2 = discontinuity of the surface, 3 = fragmentation). Lesions that received a score of 2 or 3 were graded as meniscal tears. The MRI results were compared to the arthroscopic reports, which represented the gold standard, and the sensitivity of both protocols in detecting a meniscal tear was determined. Results: Of the 42 patients included in the study, 25 (11 women and 14 men) underwent arthroscopy and all demonstrated a meniscal tear. A meniscal tear was correctly diagnosed in 76% of cases with conventional MRI and in 88% of cases with high-resolution MRI (P = .0087). Conclusion: High-resolution MRI, using a surface dual-loop coil and specific sequences, which can be performed on every standard–field-strength MRI scanner, is able to significantly improve diagnostic performance for the detection of a meniscal tear of the knee joint. [Copyright &y& Elsevier]

Abstract: Purpose: To demonstrate the value of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative assessment of orbital tumors, and to present, particularly, CT and MR image data fusion for surgical planning and performance in computer-assisted navigated surgery of orbital tumors. Materials and methods: In this retrospective case series, 10 patients with orbital tumors and associated complaints underwent MDCT and MRI of the orbit. MDCT was performed at high resolution, with a bone window level setting in the axial plane. MRI was performed with an axial 3D T1-weighted (w) gradient-echo (GE) contrast-enhanced sequence, in addition to a standard MRI protocol. First, MDCT and MR images were used to diagnose tumorous lesions compared to histology as a standard of reference. Then, the image data sets from CT and 3D T1-w GE sequences were merged on a workstation to create CT–MR fusion images that were used for interventional planning and intraoperative image guidance. The intraoperative accuracy of the navigation unit was measured, defined as the deviation between the same landmark in the navigation image and the patient. Furthermore, the clinical preoperative status was compared to the patients’ postoperative outcome. Results: Radiological and histological diagnosis, which revealed 7 benign and 3 malignant tumors, were concordant in 7 of 10 cases (70%). The CT–MR fusion images supported the surgeon in the preoperative planning and improved the surgical performance. The mean intraoperative accuracy of the navigation unit was 1.35mm. Postoperatively, orbital complaints showed complete regression in 6 cases, were ameliorated notably in 3 cases, and remained unchanged in 1 case. Conclusion: CT and MRI are essential for the preoperative assessment of orbital tumors. CT–MR image data fusion is an accurate tool for planning the correct surgical procedure, and can improve surgical results in computer-assisted navigated surgery of orbital tumors. [Copyright &y& Elsevier]

Background and Purpose: Today, functional endoscopic sinus surgery (FESS) is performed in most of the patients with sinonasal inflammatory disease. The postoperative imaging findings of FESS in multidetector computed tomography (MDCT) considerably differ from those of historic Caldwell-Luc (CL) maxillary sinus surgery which is an uncommon procedure today. Thus, the postoperative CL imaging findings may lead to diagnostic confusion and misinterpretation. Therefore, this study explicitly presents the MDCT findings of post-CL patients which have not been described previously. Methods: Twenty-eight patients with clinically suspected sinusitis and documented history of CL-procedure underwent 16 row MDCT (MDCT Mx8000 IDT Philips) with multiplanar reconstructions of the paranasal sinuses in the axial plane. The following parameters were used: 140kV, 50mAs; 16mmx0.75mm detector collimation; 1mm reconstructed slice thickness; 0.5mm increment. The studies were reconstructed with a bone algorithm (W3000/L600; 1mm slice thickness) in axial plane and coronal plane (3mm slice thickness). The images were retrospectively evaluated for the presence of normal surgery-related and pathological findings. Results: Surgery-related imaging characteristics presented as follows: an anterior and a medial bony wall defect and sclerosis and sinus wall thickening were observed in all 28/28 cases (100%). Collaps of the sinus cavity was seen in 26/28 cases (92.9%). Furthermore, inflammatory disease of the operated sinus(es) was found in 23/28 cases (82.1%): 14/28 patients (50%) had inflammatory mucosal thickening of the operated sinus(es) as well as of other sinonasal cavities and 9/28 patients (32.1%) had inflammatory mucosal thickening limited to the operated sinus(es). A postoperative mucocele was depicted in 3/28 cases (10.7%). 2/28 patients (7.1%) showed neither maxillary nor other mucosal swelling. Conclusion: MDCT with multiplanar reconstructions is a precise method to evaluate post-CL patients and helps to differentiate normal surgery-related findings, which may mimic pathology, from real pathological findings. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Cutaneous invasion by direct infiltration and metastasis, in malignant head and neck tumors, has a distinct impact on therapeutic options, especially surgical procedures, curative intent, and overall prognosis. Therefore, the purpose of this study was to determine the diagnostic accuracy of MDCT in detecting cutaneous invasion by malignant head and neck tumors. Materials and methods: Nineteen patients with malignant head and neck tumors and clinical suspicion of cutaneous invasion routinely underwent contrast-enhanced 16-row MDCT (Philips MDCT MX 8000) of the region of interest in the axial plane before surgical intervention. The following parameters were used: 16mm×0.75mm detector collimation; 3mm reconstructed slice thickness; 1.5mm increment; 0.75s rotation speed; 120kV, 200mAs; and 100ml non-ionic contrast agent, i.v., with a flow of 2.0ml/s and a scan delay of 50s. The studies were reconstructed with a soft tissue algorithm (W400, L100 HU), and coronal and sagittal planes were also reconstructed. The axial images were retrospectively reviewed in consensus by two radiologists for the evidence of cutaneous invasion blinded to the histological results. The MDCT results were correlated with histology that was obtained by punch biopsy or surgery. Results: MDCT correctly revealed 11 of 11 cases with cutaneous invasion, and correctly excluded 4 of 8 cases without cutaneous invasion. The diagnostic accuracy of MDCT in detecting cutaneous invasion showed a sensitivity of 100%, a specificity of 50%, and an overall accuracy of 79%. Conclusion: MDCT reconstructed with a soft tissue algorithm has a good sensitivity and moderate overall accuracy in detecting cutaneous invasion by malignant head and neck tumors. [Copyright &y& Elsevier]

Purpose: To demonstrate the value of multi detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative work up of temporal bone tumors and to present, especially, CT and MR image fusion for surgical planning and performance in computer assisted navigated neurosurgery of temporal bone tumors. Materials and Methods: Fifteen patients with temporal bone tumors underwent MDCT and MRI. MDCT was performed in high-resolution bone window level setting in axial plane. The reconstructed MDCT slice thickness was 0.8 mm. MRI was performed in axial and coronal plane with T2-weighted fast spin-echo (FSE) sequences, un-enhanced and contrast-enhanced T1-weighted spin-echo (SE) sequences, and coronal T1-weighted SE sequences with fat suppression and with 3D T1-weighted gradient-echo (GE) contrast-enhanced sequences in axial plane. The 3D T1-weighted GE sequence had a slice thickness of 1mm. Image data sets of CT and 3D T1-weighted GE sequences were merged utilizing a workstation to create CT-MR fusion images. MDCT and MR images were separately used to depict and characterize lesions. The fusion images were utilized for interventional planning and intraoperative image guidance. The intraoperative accuracy of the navigation unit was measured, defined as the deviation between the same landmark in the navigation image and the patient. Results: Tumorous lesions of bone and soft tissue were well delineated and characterized by CT and MR images. The images played a crucial role in the differentiation of benign and malignant pathologies, which consisted of 13 benign and 2 malignant tumors. The CT-MR fusion images supported the surgeon in preoperative planning and improved surgical performance. The mean intraoperative accuracy of the navigation system was 1.25 mm. Conclusion: CT and MRI are essential in the preoperative work up of temporal bone tumors. CT-MR image data fusion presents an accurate tool for planning the correct surgical procedure and is a benefit for the operational results in computer assisted navigated neurosurgery of temporal bone tumors. [ABSTRACT FROM AUTHOR]

Abstract: Diffusion weighted imaging of non-CNS tissue has attracted much attention during the last years. Its capability of probing the microstructure of a biologic tissue at a sub-millimeter range is used to evaluate its diffusion capacity, which is tissue specific and can be used for tissue characterization. Processes involving bone marrow where the primary target for DWI during the last years. Most experience has been gained for differentiating benign from pathologic vertebral compression fractures, which can be reliably done when quantitative diffusion measurements are available. However, preliminary results exist indicating that this non-invasive technique may be a potential tool for therapy monitoring, which will revise the management of cancer patients. Moreover, this will be the first non-invasive and quantifiable tool for evaluating the effectiveness of modern tumor treatment. In this article, we will give an overview on the current status of DWI in the evaluation of bone marrow alterations; on currently available DWI techniques and a short out-look on future aspects of DWI in bone marrow pathologies. [Copyright &y& Elsevier]