A. M. De Schepper

Tuberculosis of the central nervous system: overview of neuroradiological findings

Abstract. This article presents the range of manifestations of tuberculosis (TB) of the craniospinal axis. Central nervous system (CNS) infection with Mycobacterium tuberculosis occurs either in a diffuse form as basal exudative leptomeningitis or in a localized form as tuberculoma, abscess, or cerebritis. In addition to an extensive review of computed tomography and magnetic resonance features, the pathogenesis and the relevant clinical setting are discussed. Modern imaging is a cornerstone in the early diagnosis of CNS tuberculosis and may prevent unnecessary morbidity and mortality. Contrast-enhanced MR imaging is generally considered as the modality of choice in the detection and assessment of CNS tuberculosis.

Imaging findings in diffuse axonal injury after closed head trauma

Abstract. Even in patients with closed head trauma, brain parenchyma can be severely injured due to disruption of axonal fibers by shearing forces during acceleration, deceleration, and rotation of the head. In this article we review the spectrum of imaging findings in patients with diffuse axonal injuries (DAI) after closed head trauma. Knowledge of the location and imaging characteristics of DAI is important to radiologists for detection and diagnosis. Common locations of DAI include: cerebral hemispheric gray-white matter interface and subcortical white matter, body and splenium of corpus callosum, basal ganglia, dorsolateral aspect of brainstem, and cerebellum. In the acute phase, CT may show punctate hemorrhages. The true extent of brain involvement is better appreciated with MR imaging, because both hemorrhagic and non-hemorrhagic lesions (gliotic scars) can be detected. The MR appearance of DAI lesions depends on several factors, including age of injury, presence of hemorrhage or blood-breakdown products (e. g., hemosiderin), and type of sequence used. Technical aspects in MR imaging of these patients are discussed. Non-hemorrhagic lesions can be detected with fluid attenuated inversion recovery (FLAIR), proton-density-, or T2-weighted images, whereas gradient echo sequences with long TE increase the visibility of old hemorrhagic lesions.

MR mammography in the pre-operative staging of breast cancer in patients with dense breast tissue: comparison with mammography and ultrasound

The aim of this study was to determine whether pre-operative MR mammography could predict the extent of breast cancer in patients with dense breasts or whether dense parenchyma will lead to false-positive or inconclusive examinations. Sixty-seven patients with dense breasts with a malignant breast tumor planned for conservative surgery were reviewed. Detection rates of mammography, ultrasound, and MR mammography were studied, and the diameters of the lesions were measured and compared with pathological examination. Pathology revealed breast cancer in 65 patients. Sensitivity for detection of index lesions was 83% for mammography, 70.8% for ultrasound, and 98% for MR mammography. Mammography underestimated tumor extent in 37%, ultrasound in 40%, and MR in 12.5%. Of the 20 patients (31%) with multifocal or multicentric carcinoma, mammography detected the lesions in 35%, ultrasound in 30%, and MR in 100%, with a false-positive rate of 12.5, 14, and 23%. The MR mammography is more accurate in assessing tumor extent and multifocality in patients with dense breasts, but benign changes may lead to false-positive examinations.

Intracranial hemorrhage: principles of CT and MRI interpretation

Abstract. Accurate diagnosis of intracranial hemorrhage represents a frequent challenge for the practicing radiologist. The purpose of this article is to provide the reader with a synoptic overview of the imaging characteristics of intracranial hemorrhage, using text, tables, and figures to illustrate time-dependent changes. We examine the underlying physical, biological, and biochemical factors of evolving hematoma and correlate them with the aspect on cross-sectional imaging techniques. On CT scanning, the appearance of intracranial blood is determined by density changes which occur over time, reflecting clot formation, clot retraction, clot lysis and, eventually, tissue loss. However, MRI has become the technique of choice for assessing the age of an intracranial hemorrhage. On MRI the signal intensity of intracranial hemorrhage is much more complex and is influenced by multiple variables including: (a) age, location, and size of the lesion; (b) technical factors (e.g., sequence type and parameters, field strength); and (c) biological factors (e.g., pO2, arterial vs venous origin, tissue pH, protein concentration, presence of a blood-brain barrier, condition of the patient). We discuss the intrinsic magnetic properties of sequential hemoglobin degradation products. The differences in evolution between extra- and intracerebral hemorrhages are addressed and illustrated.

New concepts in understanding evolution of desmoid tumors: MR imaging of 30 lesions

Abstract The objective of this study was to evaluate the appearance and the natural evolution of desmoid tumors on MR imaging, given histologic correlation. The MR images of 30 desmoids (20 primary and 10 recurrent) in 26 patients were scored for a multiplicity of morphological parameters, signal intensity (SI) on different pulse sequences, and behavior after contrast administration. Natural evolution was evaluated in 2 primary and 3 recurrent lesions, and correlated with evolution on histologic specimens. Desmoid tumors are mostly found in muscles of shoulder and hip girdle and are often fusiform with partially ill-defined margins. Rare subcutaneous desmoids have a more stellar morphology. Variable amounts of low-SI areas are present on all sequences. On T1-weighted images (T1-WI), most lesions are near homogeneous and isointense to muscle, whereas on T2-WI they are more heterogeneous with an overall SI equal to or slightly lower than fat. Histologic correlation reveals that SI on T2-WI cannot be explained solely by cellularity. After initial growth, spontaneous evolution of desmoids is characterized by shrinking and an increase in low-SI areas on T2-WI. While distal lesions shrink, the more recent lesions in asynchronous multicentric desmoids have a tendency to develop proximally in the same limb, and should not be confused with recurrences. Fast growth, extracompartmental spread, and bone involvement are often seen in recurrences. Follow-up MR imaging of desmoids indicates natural regression of desmoids and more aggressive behavior of recurrences, which may justify a more conservative therapeutic approach.

Preoperative breast MRI in patients with invasive lobular breast cancer

To investigate the use of MRI in preoperative characterization of invasive lobular breast cancer (ILC) and in detection of multifocal/multicentric disease. We retrospectively reviewed T1-weighted FLASH 3D precontrast and postcontrast MR images together with subtraction images of 26 women with histopathologically proven invasive lobular cancer. Two experienced radiologists described tumor patterns of ILC independently. MR findings of unifocal, multifocal, single quadrant and multiquadrant disease were correlated with results of other imaging techniques and compared with histopathological findings as gold standard. Most ILC presented on MRI as a single spiculated/irregular, inhomogeneous mass (pattern 1, n=12) or as a dominant lesion surrounded by multiple small enhancing foci (pattern 2, n=8). Multiple small enhancing foci with interconnecting enhancing strands (pattern 3) and an architectural distortion (pattern 4) were both described in three cases. There was one case of a focal area of inhomogeneous enhancement (pattern 5) and one normal MR examination (pattern 6). Unifocal and multifocal lesions were identified on MRI in four patients with normal conventional imaging. In nine women, multiple additional lesions or more extensive multiquadrant disease were correctly identified only on MRI. MRI may play an important role in the evaluation of patients with ILC, which is often difficult to diagnose on clinical examination and conventional imaging and more likely occur in multiple sites and in both breasts. However, false-negative MR findings do occur in a small percentage of ILC.

Magnetic resonance imaging of soft tissue tumors.

Abstract. This article outlines the ability of MR imaging in staging, grading, tissue characterization, and posttherapeutic surveillance of soft tissue tumors. Well-known staging parameters, such as extent, relationship with adjacent structures, and detection of intralesional necrosis, are used in the MR protocol for locoregional staging. Bone scintigraphy and high-resolution CT scan of the lungs are best methods for ruling out metastatic spread. A variety of (solitary or combinations of) grading parameters are described in the radiological literature. The role of MR imaging is to afford recognition of these lesions that need further aggressive work-up, excluding all others. Despite controversial reports, the definite role of MR imaging in grading of soft tissue tumors seems to become established. As for grading, a lot of individual imaging characteristics used for tissue characterization have low sensitivity, but combinations of parameters (age, site, signal intensities) are more useful and often allow to predict a specific diagnosis or to narrow down the list of differential diagnoses. Local recurrences of soft tissue tumors are frequent and can be detected accurately by an easy-to-use MR algorithm.

The correlation of preoperative CT, MR imaging, and clinical staging (FIGO) with histopathology findings in primary cervical carcinoma

The aim of this study was to compare the preoperative findings of abdominal/pelvic CT and MRI with the preoperative clinical International Federation of Obstetrics and Gynecology (FIGO) staging and postoperative pathology report in patients with primary cancer of the cervix. Thirty-six patients with surgical–pathological proven primary cancer of the cervix were retrospectively studied for preoperative staging by clinical examination, CT, and MR imaging. Studied parameters for preoperative staging were the presence of tumor, tumor extension into the parametrial tissue, pelvic wall, adjacent organs, and lymph nodes. The CT was performed in 32 patients and MRI (T1- and T2-weighted images) in 29 patients. The CT and MR staging were based on the FIGO staging system. Results were compared with histological findings. The group is consisted of stage 0 (in situ):1, Ia:1, Ib:8, IIa:2, IIb:12, IIIa:4, IVa:6, and IVb:2 patients. The overall accuracy of staging for clinical examination, CT, and MRI was 47, 53, and 86%, respectively. The MRI incorrectly staged 2 patients and did not visualize only two tumors; one was an in situ (stage-0) and one stage-Ia (microscopic) disease. The MRI is more accurate than CT and they are both superior to clinical examination in evaluating the locoregional extension and preoperative staging of primary cancer of the cervix.

Distribution and incidence of degenerative spine changes in patients with a lumbo-sacral transitional vertebra

The purpose of this prospective study was to determine the overall incidence and distribution of lumbo-sacral degenerative changes (i.e. disc protrusion or extrusion, facet degeneration, disc degeneration, nerve root canal stenosis and spinal stenosis) in patients with and without a lumbo-sacral transitional vertebra (LSTV). The study population consisted of 350 sequential patients with low back pain and/or sciatica, referred for medical imaging. In all cases CT scans of the lumbosacral region were obtained. In 53 subjects (15%) an LSTV was found. There was no difference in overall incidence of degenerative spine changes between the two groups. We did find, however, a different distribution pattern of degenerative changes between patients with and those without an LSTV Disc protrusion and/or extrusion occurred more often at the level suprajacent to the LSTV than at the same level in patients without LSTV (45.3% vs 30.3%). This was also the case for disc degeneration (52.8% vs 28%), facet degeneration (60.4% vs 42.6%) and nerve root canal stenosis (52.8% vs 27.9%). For spinal canal stenosis there was no statistically significant difference between the two categories. In conclusion, our findings indicate that an LSTV does not in itself constitute a risk factor for degenerative spine changes, but when degeneration occurs, it is more likely to be found at the disc level above the LSTV.

Sclerosing bone dysplasias: genetic and radioclinical features

Abstract. Although knowledge of basic genetics in the field of sclerosing bone dysplasias is progressing, the radiologist still plays a pivotal role in the diagnosis of this relatively poorly understood group of disorders. Based on a target site approach, these anomalies are classified into three groups. Within each group, further differentiation can be made by distinctive clinical findings and by mode of inheritance: (a) dysplasias of endochondral bone formation: osteopetrosis (Albers-Schönberg disease), pycnodysostosis, enostosis, osteopoikilosis, osteopathia striata (Voorhoeve disease); (b) dysplasias of intramembranous bone formation: progressive diaphyseal dysplasia (Camurati-Engelmann disease) and variants, hyperostosis corticalis generalisata (Van Buchem disease) and variants; and (c) mixed sclerosing dysplasias: melorheostosis (Leri disease) and overlap syndromes.