Hip fracture risk and proximal femur geometry from DXA scans.

In this retrospective study of hip fracture risk evaluation from hip dual-energy X-ray absorptiometry (DXA) scans, our objectives were to determine which part of the femoral neck length contributes most to the fracture risk and to define a geometric parameter better than hip axis length (HAL) for discriminating hip fracture patients. Forty-nine Caucasian women with a nontraumatic femoral neck fracture were matched on age to 49 normal women and on both age and femoral neck bone mineral density (BMD) to 49 unfractured women. In addition to BMD, geometric parameters including neck-shaft angle, neck width and several HAL segments were evaluated by discriminant analysis to determine which was the best hip fracture discriminator. Neck-shaft angle had a limited influence on the hip fracture risk. Age-related bone loss was associated with a neck width increase in unfractured and fractured patients. HAL was significantly longer in fractured patients and was a significant discriminator between fractured patients and normal controls. HAL was not significant as a discriminator between fractured and low-BMD unfractured patients. The intertrochanter-head center distance (from the intertrochanteric line to the femoral head center) coincides with the femoral lever arm and includes no segments that adapt to BMD changes, such as the greater trochanter-intertrochanter distance. Among all tested lengths, this segment was the part of HAL that discriminated best between fractured and low-BMD unfractured patients. A longer intertrochanter-head center distance increased the risk of femoral neck fracture among low-BMD patients. Including automatic measurement of this segment in standard DXA protocols may prove useful in identifying patients at high risk for hip fracture. At present, HAL remains the easier neck length to measure, but automatic evaluation of the intertrochanter-head center distance must be a goal for future image analysis development.

A method of radio-frequency inhomogeneity correction for brain tissue segmentation in MRI.

An automatic method of correcting radio-frequency (RF) inhomogeneity in magnetic resonance images is presented. The method considers that image intensity variation due to radio-frequency inhomogeneity contains not only low frequency components, but also high frequency components. The variation is regarded as a multiplication of low frequency (capacity variation of coil) and the frequency of object (true image). The efficiency of the proposed method is illustrated with the aid of both phantom and physical images. The impact of the inhomogeneity correction on brain tissue segmentation is studied in detail. The results show significant improvement of the tissue segmentation after inhomogeneity correction.

[Digital radiography of the thorax]. / Radiologie numérique du thorax.

Digital radiography of the thorax can, now be substituted to conventional chest radiography. Computed radiography with phosphor plates and the new selenium detector are emphasized. The major image processing are explained. Successively the main other methods of digital radiography are described: scanning equalization radiography, laser-digitized radiography and multiwire proportional chambers. Then the advantages and the drawbacks of chest computed radiography are extensively reviewed.

[Cervico-mediastinal recurrences of differentiated thyroid cancers: value of MRI]. / Récidives cervico-médiastinales des cancers thyroïdiens différenciés: valeur de l'irm.

AIM: The aim of this study was to evaluate the ability of MRI to detect recurrent differentiated thyroid carcinomas developed in the neck or the upper mediastinum. RESULTS: MRI was performed in 25 patients, and was compared in 5 cases with surgery. In 20 cases it was compared with I-131 scintigraphy (100 mCi in 14 cases and 5 mCi in 6 cases). The sensibility, specificity and overall accuracy of MRI was respectively: 100%, 66.6%, 82.6%. COMMENTARY: MRI is a good technique to detect recurrent thyroid carcinomas. It is specially interesting to investigate patients with a biological suspicion of recurrence and a negative scintigraphy. Mediastinal localisations that cannot be detected by US can be detected by MRI.

Evolution of bone densitometry in patients with myeloma treated with conventional or intensive therapy.

BACKGROUND: Demineralization is a common hallmark of multiple myeloma (MM) that can be evaluated by dual-energy X-ray absorptiometry (DEXA). The evolution of lumbar and whole body bone density were investigated by DEXA in patients with MM treated by conventional or intensive therapy supported by autologous blood stem cell transplantation. METHODS: Sixty six patients younger than 66 years with MM were randomly assigned to either conventional (30 patients, Group A) or intensive therapy supported by autologous blood stem cell transplantation (36 patients, Group B). For all patients, lumbar bone mineral density (BMD) was measured by DEXA at diagnosis and 13.2 +/- 4.2 months after the initiation of treatment. Whole body examinations were performed in 45 patients; in addition to whole body BMD, independent BMD values were recorded for various skeletal sites. RESULTS: At diagnosis, mean lumbar Z score (lumbar mean BMD value) was low (-1.24 +/- 1.45) without any significant difference between the 2 groups. Under treatment, lumbar BMD increased 0.7% in Group A and 4.6% in Group B (P = 0.02). This difference was mainly related to nonresponders in group A who featured a lumbar BMD change of -3.9%, whereas patients in remission in both groups displayed a 4.1% increase (P < 0.001). There was a correlation between the variation of lumbar BMD and the decrease of the serum or urinary monoclonal component (r = 0.34, P = 0.006). After intensive therapy, increase of lumbar BMD was higher in men than in women (7.2% vs. 1%, P = 0.005) perhaps because of variations in hormonal status in women. Unexpectedly, whole body BMD decreased in responders (-3%) because of a decrease in appendicular BMD outweighing the increase in axial BMD. This suggests a redistribution from cortical to cancellous bone in patients with MM responsive to chemotherapy. CONCLUSION: Bone densitometry is a marker of treatment response that may be particularly useful in nonsecretory and light chain MM. Moreover, it provides new information on bone remodeling in patients treated for MM, which may have therapeutic consequences.

Magnetic resonance imaging in patients with penile carcinoma.

The aim of the study was to determine the role of pre-operative magnetic resonance imaging (MRI), with and without contrast enhancement, in patients with penile carcinoma. Nine patients with a penile cancer were studied. The staging of the tumours was performed by clinical examination, MRI and surgery, according to the TNM classification. Six patients had primary tumours, of clinical stage T1 (n = 1) and T2 (n = 5). Three other patients had been previously treated and presented with a local recurrence of clinical stage T2. Surface-coil MRI was performed at 0.5 T with T1 weighted sequences before and after gadolinium-DOTA, and T2 weighted sequences. MRI results were compared with the clinical and surgical findings. T1 weighted sequences did not clearly demonstrate the margins of the tumours. T2 weighted sequences were the more useful in five patients, whereas contrast enhanced T1 weighted sequences allowed better delineation of the lesions in only three patients. Therefore, an imaging protocol should include spin echo T2 weighted sequences. Clinical examination correctly staged six of nine tumours; MRI, seven of nine tumours and the combination of both examinations, eight of nine tumours. MRI provided good evaluation of tumoral invasion into the penile shaft.

Imaging of choroid plexus infection by Stomatococcus mucilaginosus in neutropenic patients.

We report two neutropenic patients with Stomatococcus mucilaginosus meningitis and choroid plexus involvement on neuroimaging studies. CT and MR showed abnormal enlargement of the choroid plexus in one lateral ventricle and intense enhancement. In one patient there was edema in the periventricular white matter adjacent to the involved choroid plexus; in both patients there was enhancement of the ependyma.

MR of cerebral aspergillosis in patients who have had bone marrow transplantation.

PURPOSE: To assess the CT and MR appearance of cerebral aspergillosis in patients who have undergone bone marrow transplantation. METHODS: The imaging and clinical data of five patients with cerebral aspergillosis were reviewed retrospectively and compared with autopsy findings. RESULTS: Lesions are often located in the basal ganglia and demonstrate an intermediate signal intensity within surrounding high-signal areas on long-repetition-time MR scans. The lesions were multiple in four of the five patients and more numerous on MR images than on CT scans. The lesions (which demonstrate no parenchymal enhancement) are consistent with acute infarcts as confirmed at autopsy. In the large lesions, there is early intravascular and meningeal enhancement, as expected in acute infarcts involving an appreciable portion of the territory of a cerebral artery. CONCLUSION: The diagnosis of early cerebral infarction in a patient considered at risk for invasive aspergillosis, even without overt pulmonary disease, is an indication to institute aggressive antifungal therapy.

Dual-energy X-ray absorptiometry of the calcaneus: comparison with vertebral dual-energy X-ray absorptiometry and quantitative computed tomography.

The purpose of this study was to determine the efficacy of using bone mineral measurements of the calcaneus to evaluate osteoporosis. Dual energy X-ray absorptiometry (DXA) of the calcaneus was compared with posteroanterior lumbar absorptiometry (DXA) and vertebral quantitative computed tomography (QCT) measurements in 171 white women (78 normal and 93 osteoporotic). DXA measurement of os calcis mineralization decreased significantly in osteoporosis, but to a lesser extent than in vertebral sites. In normal subjects, good correlations were observed between calcaneal and lumbar DXA (0.69) and QCT (0.56). In subjects with vertebral fractures, there was also good correlation between calcaneal DXA and QCT (0.59-0.69). This suggests that trabecular bone in calcaneus and vertebrae have related involution in cases of vertebral osteoporosis. However, the extent of bone loss is less marked in the calcaneus than in the vertebrae and is not sufficient to be accurately measured over time. We conclude, therefore, that although the global densitometric measurement at this site is not sufficiently sensitive for general use, it can be useful as a epidemiological research tool.

CT and MR patterns of spinal involvement in Richter syndrome.

Richter syndrome is the transformation of chronic lymphocytic leukemia (CLL) into large cell lymphoma. Besides the involvement of lymph nodes, liver, and spleen, bone lesions occur infrequently. We report one case of a patient with a paraspinous mass and destruction of the vertebra by large cell transformation of CLL seen on CT and MRI. There was nothing specific about the clinical presentation, imaging characteristics, and histopathological pattern of bone biopsy that would allow for confident differentiation from infectious spondylitis.

[Radiological aspects of invasive aspergillosis]. / Aspects radiologiques des aspergilloses invasives.

Invasive aspergillosis is a life-threatening illness, whose diagnosis is difficult: clinical signs are indeed not specific, and biological and mycological exams are not always conclusive. Radiological exams are essential for the diagnosis of this disease allowing to start an early intensive appropriate therapy. According to the literature and to their own experience the authors report the main radiological patterns with emphasis on the pulmonary and cerebral affections.

Ultrasound attenuation imaging in the os calcis: an improved method.

A complete assessment of the broadband ultrasonic attenuation (BUA) distribution within the os calcis was made using an ultrasonic mechanical scanning device with focused transducers. Measurements were performed on 12 os calces removed from fresh female cadavers. We present the first images of BUA of the os calcis. Reasonably high quality images were obtained compared to computed tomography. The resolution provided by the focused transducers is approximately 4 or 5 mm in the focal zone. Compared to dual energy X-ray absorptiometry (DEXA) or quantitative computed tomography, ultrasound imaging of the os calcis offers the possibility of controlling the placement, size and shape of the region of interest and to use multiple measurement sites. DEXA was used systematically to measure the bone mineral density (BMD) of the os calces. A highly significant correlation between BMD and BUA was found (r = 0.97 p < 0.001).

[Radiography of the thorax with phospholuminescent screens]. / La radiographie du thorax avec les écrans phospholuminescents.

Image digitalization can be performed in several ways: equalization of the x-ray beam (Scanning Equalization Radiography and Advanced Multiple-Beam Equalization Radiography), digital fluorography, use of linear computed tomography detectors, digitalization of radiographic films and memory screens. Phospholuminescent screens use an x-ray receptor which is able to store the x-ray energy. This latent energy is then extracted and can be processed to obtain images with matrices ranging between 1,760 x 2,140 and 1,770 x 2,370. Several types of image processing systems can be used depending on the pathology investigated. The blurred mask substraction method is the most widely used. The first clinical results demonstrate a reduction in patient irradiation and performances equal to or better than those of standard x-rays.

[Contribution of medical imaging. What examinations for what indications?]. / Apports de l'imagerie médicale. Quels examens dans quelles indications?

Osteoporosis is an obvious diagnosis in patients with fractures due to decreased bone mass. However, in many cases, major bone loss is infraclinical and requires quantification. Two methods are available to achieve this, i.e., dual energy X ray absorptiometry (DXA) and quantitative computerized tomography (QCT). QCT, which measures the central trabeculae in the lumbar vertebra, is a sensitive technique and has demonstrated a mean bone loss of 1.1 p. cent per year in cancellous bone. However, use of QCT is limited by the high radiation exposure and costs involved. Dual energy X ray absorptiometry is a highly reproducible method which ensures satisfactory correction of soft tissue effects and entails only low exposures to radiation. However, errors occur in patients with aortic calcifications, posteriorly located osteophytes or scoliosis. The optimal frequency of quantitative evaluations of bone varies with the type of disease; in patients with osteoporosis, it is unnecessary to perform evaluations more than once every three years to monitor the course of the disease.

[Measurement of vertebral bone density. Quantitative tomodensitometry or dual-photon absorptiometry?]. / Mesure de la densité osseuse vertébrale. Tomodensitométrie quantitative ou absorptiométrie biphotonique?

We have compared vertebral bone density measurements (QCT and DXA) in women in the postmenopausal period who underwent both examinations. Our aim was to study the results and to define the respective indications of QCT and DXA in various clinical pictures of osteoporosis. The subjects of the study were distributed into various groups according to the presence or absence of vertebral collapse and/or peripheral fractures. The results of the measurements were expressed as Z-scores (deviation from age-normal average) to suppress the age effect and to make comparison between both methods possible. The values of both measurements are significantly lower in case of vertebral involvement. QCT is more sensitive than DXA to discriminate vertebral collapse. A vertebral fragility threshold was defined at a Z-score of -1 with DXA and -1.25 with QCT, corresponding to the best sensitivity for an acceptable specificity. The results of densitometry suggest that there is a peripheral osteoporosis, different from vertebral osteoporosis, as early as the postmenopausal period. Since DXA is easy to implement, it can be used to screen osteoporosis. When the vertebral measurement with DXA is normal although osteoporosis is obvious (previous collapse or fracture), QCT must be used as it is more sensitive.

Bone densitometry in patients with multiple myeloma.

PURPOSE, PATIENTS, AND METHODS: We performed dual-energy x-ray absorptiometry in 10 selected patients with aggressive multiple myeloma in whom substantial tumor mass reduction was achieved after high-dose chemoradiotherapy followed by autologous blood stem cell transplantation. RESULTS: In most cases, bone mineral density (BMD) of the spine was initially low (Mean Z score: -2.69, SEM 0.76) and dramatically increased after treatment (mean increase 16.4%; 7.7% with 95% confidence interval 2.2 to 12.2, excluding one patient whose spine BMD increased by 94.8%). In contrast, skeletal roentgenograms, computed tomographic scans, and magnetic resonance imaging did not reveal any significant improvement of patients' bone lesions. CONCLUSIONS: In patients with multiple myeloma, bone densitometry could be a useful way to assess the efficacy of treatment on bone status.