The purpose of this study was to derive parameters that predict which high-energy blunt trauma patients should undergo computed tomography (CT) for detection of chest injury.
To evaluate the diagnostic accuracy and interobserver variance of magnetic resonance (MR) enteroclysis in the diagnosis of small-bowel neoplasms, with small-bowel endoscopy, surgery, histopathologic analysis, and follow-up serving as standards of reference, and to identify MR enteroclysis characteristics capable of enabling discrimination between benign and malignant small-bowel neoplasms.This study was performed in accordance with the guidelines of the institutional review board, and the requirement for informed consent was waived. MR enteroclysis studies of 91 patients (43 women, 48 men; age range, 18-83 years) were retrospectively evaluated by two radiologists blinded to clinical details. Only studies explicitly performed to investigate or exclude the presence of small-bowel neoplasms were included. Radiologic findings were compared with findings of double-balloon endoscopy (n = 45), surgery (n = 18), esophagogastroduodenoscopy (n = 3), ileocolonoscopy (n = 2), autopsy (n = 2), and clinical follow-up for more than 18 months (n = 21). Efficacy parameters were calculated with 95% confidence intervals. Tumor characteristics were compared with the Student t test and the Fisher exact test.Readers 1 and 2 interpreted 31 and 33 studies, respectively, as depicting a small-bowel neoplasm and 19 and 17 studies, respectively, as depicting small-bowel malignancy. In 32 patients, the presence of small-bowel neoplasm was confirmed. In 19 of these patients, the neoplasm was malignant. Sensitivity and specificity in the diagnosis of small-bowel neoplasms was 0.91 and 0.95, respectively, for reader 1 and 0.94 and 0.97, respectively, for reader 2; the kappa value was 0.95. Factors associated with malignancy were the presence of longer solitary nonpedunculated lesions, mesenteric fat infiltration, and enlarged mesenteric lymph nodes.Eighty-six of 91 studies were correctly interpreted, resulting in an overall diagnostic accuracy of 0.95 for MR enteroclysis in the detection of small-bowel neoplasms.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.09090828/-/DC1.
In response to our publication (Gluer et al, 1990a), Wilson and colleagues (1990) proposed the adoption of a uniform terminology and corresponding abbreviation for Dual X-ray Absorptiometry (DXA). We supported this suggestion (Gluer et al, 1990b). Since then, the number of papers on DXA has increased considerably. Still, different abbreviations (DEXA, DER, DRA, QDR and DPX) for this technique for bone densitometry are used, several of which are proprietary in origin. DXA is the upgraded version of DPA (Dual Photon Absorptiometry). The nuclear source has been replaced by an X-ray source and this improved technology has gained wide-spread acceptance and distribution.
Compared with adults, limited attention has been paid to bone densitometry in children. However, due to the recognition of the importance of peak bone mass and the increased capabilities to treat children with diseases that affect bone growth and/or metabolism, bone densitometry is used more often in children. This article will discuss the available bone densitometry techniques and the limitations of their use in children. The article is concluded with a discussion on specific problems that can be encountered in pediatric bone densitometry.
textabstractCT scanners can be used to provide quantitative information on body
composition. Its main application is for bone mineral content estimation within
the lumbar vertebral body. This is usually done with a single-energy technique.
The estimates obtained with this technique are influenced by the intravertebral
fat content, which varies interindividually and with disease. Dual-energy
techniques have been proposed to solve the fat-error, but their exact value is
unknown. The aim of the studies presented in this thesis, is to evaluate different
postprocessing dual-energy methods for quantitative computed tomography for
bone mineral and fat content analysis within the trabecular region of the vertebral
body. Comparison of these methods by transforming them to a standard set of
equations, reveals that only two out of five methods would give optimal results
(chapter 3). This is confirmed in phantom studies (chapter 4). In the phantom
studies, two major problems for performing postprocessing DEQCT are
encountered: 1) the accuracy of the tissue equivalence of reference materials or
accuracy of tissue description and 2) the effective energy difference between the
site of the vertebral body and the reference device. Using a patient simulation
model, the influence of these disturbing factors on the accuracy of bone mineral
and fat content estimation is evaluated for different clinical conditions (chapters
5 and 6). The precision of the bone mineral and fat content determination with
postprocessing DEQCT is evaluated in chapter 7. In addition to an in vitro
experiment, the precision is estimated using the patient simulation model. The
results from chapters 5 through 7, show that postprocessing DEQCT can be of
value in clinical practice. Postprocessing DEQCT should be used in longitudinal
studies on bone mineral content changes, if significant changes in the bone
marrow composition are anticipated. Furthermore, postprocessing DEQCT can be
used for evaluation of fat content differences between groups of patients.
Striking differences in the fat content estimates are seen in a number of patients
with different metabolic disorders (chapter 8). It is concluded that the theoretical
superb accuracy of bone mineral measurements obtained with postprocessing
DEQCT, can be eliminated by practical problems such as improper tissue
equivalence of the reference materials and energy differences between the region
of interest and the reference device. More research is necessary to obtain an
exact knowledge of the elemental compositions and mass densities of the various anatomical structures within the vertebral body, especially intravertebral fat
tissue. Beam hardening corrections, implemented in the CT scanner, should be
evaluated for their effect on OCT
To evaluate the diagnostic accuracy of MR enteroclysis and to compare it to video capsule endoscopy (VCE) in the analysis of suspected small-bowel disease. We performed a retrospective analysis of 77 patients who underwent both MR enteroclysis and VCE and compared the findings of these studies with the findings of enteroscopy, surgery, or with the results of clinical follow-up lasting ≥2 years. Findings included malignant neoplasms (n = 13), benign neoplasms (n = 10), refractory celiac disease (n = 4), Crohn’s disease (n = 2) and miscellaneous conditions (n = 10). Specificity of MR enteroclysis was higher than that of VCE (0.97 vs. 0.84, P = 0.047), whereas sensitivity was similar (0.79 vs. 0.74, P = 0.591). In 2/32 (6.3%) patients with both negative VCE and negative MR enteroclysis a positive diagnosis was established, compared to 5/11 (45.5%) patients in whom VCE was positive and MR enteroclysis was negative (likelihood ratio 8.1; P = 0.004), 9/11 (81.8%) patients in whom MR enteroclysis was positive and VCE was negative (likelihood ratio 23.5; P < 0.0001), and all 23 patients in whom both VCE and MR enteroclysis showed abnormalities (likelihood ratio 60.8; P < 0.0001). VCE and MR enteroclysis are complementary modalities. In our study-population, MR enteroclysis was more specific than VCE, while both produced the same sensitivity.
Five postprocessing methods for dual-energy quantitative computed tomography of the vertebral body were evaluated theoretically. The methods were compared by transforming the original sets of equations to a standard set. Only two of these methods produced optimal results, namely the basic approach of Goodsitt et al and the method of Nickoloff et al. The calibration approach of Goodsitt et al will produce optimal results only if calibration materials are available that mimic the anatomic constituents of the vertebral body better than those available currently. Theoretically, the methods of Cann et al and of Laval-Jeantet et al will not produce optimal results.
