Discriminatory ability of quantitative ultrasound parameters and bone mineral density in a population-based sample of postmenopausal women with vertebral fractures: results of the Basel Osteoporosis Study.

The discriminatory potential to classify subjects with or without vertebral fractures was tested cross-sectionally with different methods for the measurement of bone status in a population-based sample of postmenopausal women. Quantitative ultrasound (QUS) measurement at the calcaneus (Lunar Achilles, Hologic Sahara), the proximal phalanges (Igea Bone Profiler), and measurement of bone mineral density (BMD) with dual-energy X-ray absorptiometry (DXA; Lunar Expert) at several anatomic sites was performed in 500 postmenopausal women (aged 65-75 years) randomly selected from the population. In addition, 50 young female subjects (20-40 years old) had QUS measurements and served as controls to express QUS results as T-score values. Radiographs of the lumbar and thoracic spine were performed in the elderly women. Two independent radiologists reviewed the X-rays for the presence of vertebral fractures. Of 486 eligible study participants, no fracture was seen in 396 participants. Single vertebral fractures were observed in 71 subjects; 19 individuals presented multiple fractures. The overall prevalence of vertebral fractures was 18.5%. Participants without vertebral fractures were compared with subjects with vertebral fractures. Normal statistical distributions were found for all bone measurement results. Risk of vertebral fracture in subjects with no and multiple vertebral fracture was estimated using age adjusted odds ratios (ORs) for QUS and dual-energy X-ray absorptiometry (DXA) values. Each SD decrease in bone measurement increased the risk of multiple vertebral fracture by 3.0 (95% CI, 1.6-5.6) for the Achilles stiffness, by 3.8 (95% CI, 1.8-8.2) for the Sahara QUI, 2.1 (95% CI, 1.3-3.4) for the Bone Profiler amplitude-dependent speed of sound (AD-SOS), and 2.1 (95% CI, 1.2-3.9) and 2.4 (95% CI, 1.3-4.3) for DXA lumbar spine and for DXA total hip, respectively. Results of a discriminant analysis showed sensitivities between 84% and 58% and specificities between 72% and 58% for the respective DXA and QUS parameters. Optimum fracture thresholds for QUS measurements derived from this analysis were calculated also. Optimum T-score threshold values for QUS measurements tended to be higher than those for DXA measurements. However, the performance of QUS measurements is at least comparable with DXA measurements in identifying subjects with multiple vertebral fractures randomly selected from the population.

A comparison of methods for enhancing the detection of areas of decreased attenuation on CT caused by airways disease.

PURPOSE: The purpose of this work was to investigate thin section CT image enhancement of subtle areas of decreased attenuation of the lung parenchyma in suspected airways disease. METHOD: Forty-seven consecutive patients with chronic sputum production underwent pulmonary function tests and high resolution CT (HRCT). Single section inspiratory (INSP), expiratory (EXP), and minimum intensity projection (MINIP) images through the lower lobes were acquired. A histogram stretch was applied to the INSP and MINIP images, generating two further image formats. The five image types were compared for the extent of decreased attenuation, observer confidence, and correlations with pulmonary function tests. RESULTS: Interobserver variation was lowest with MINIP images (mean weighted K: MINIP 0.70, INSP sections 0.65, other image formats < or =0.48). Observers were most confident with EXP and MINIP images. EXP sections identified more disease than MINIP images (p<0.001). Correlations with pulmonary function tests were similar for each image format. CONCLUSION: The HRCT changes of small airways disease are enhanced with image postprocessing. MINIP images are associated with increased observer confidence and agreement as compared with HRCT alone.

Mechanism of mosaic attenuation of the lungs on computed tomography in induced bronchospasm.

The purpose of this study was to investigate whether hypoxic pulmonary vasoconstriction is the major determinant of the computed tomography (CT) pattern of mosaic attenuation in asthmatic patients with induced bronchoconstriction. Thin-section CT was performed at suspended full inspiration immediately and 30 min after methacholine bronchoprovocation in 22 asthmatic subjects, who were randomly assigned to breathe room air (group A, n = 8), oxygen via nasal prongs at 5 l/min (group B, n = 8), and oxygen via face mask at 12 l/min (group C, n = 6). CT changes were quantified in terms of global lung density and density in hypodense and hyperdense areas. Lung parenchymal density increases were greatest in group C and greater in group B than in group A, globally (P = 0.03) and in hypodense regions (P = 0.01). On bivariate analysis, the only change in cross-sectional area was related to change in global density. In hypodense regions, density change was related both to reduction in cross-sectional area (P < 0.0005) and to oxygen administration (P = 0.01). After correction for changes in global lung density, only oxygen was independently related to density increase in hypodense areas (P = 0.02). In induced bronchoconstriction, the CT appearance of mosaic attenuation can be largely ascribed to hypoxic vasoconstriction rather than to changes in lung inflation.

Imaging the 'dirty lung'--has high resolution computed tomography cleared the smoke?

The histopathological abnormalities that characterize cigarette smokers' lung damage have been widely studied, but these microscopic changes do not fully explain the radiographic features that have been loosely termed the 'dirty lung'. High resolution computed tomography is not only more sensitive for the detection of early emphysema, it has also provided the imaging correlates of subtle parenchymal changes of smokers, for example, respiratory bronchiolitis - interstitial lung disease. Nevertheless, some aspects of the radiographic 'dirty lung' remain enigmatic.

MR arthrographic findings in tenosynovitis of the long bicipital tendon of the shoulder.

PURPOSE: To assess the MR arthrographic findings of bicipital tenosynovitis in correlation with arthroscopy. DESIGN AND PATIENTS: The shoulder MR arthrographies of 500 consecutive patients were retrospectively analyzed for signs of bicipital tenosynovitis and associated pathologies. Forty patients (8%) had MR evidence of bicipital tenosynovitis, but only 17 (3%) with arthroscopic confirmation were included in the study. The MR findings in these patients were compared with those of 10 patients with rotator cuff lesions but arthroscopically normal long biceps tendons. MR arthrography was performed with 10-15 ml of a 250 mmol/l gadoterate meglumine (Gd-DOTA) solution injected under fluoroscopic guidance, and transaxial, oblique coronal and sagittal MR sequences were obtained. RESULTS: All 17 patients showed one or more abnormal findings: signal increase in the tendon with or without fusiform distension was seen in 12, surface irregularities in six, adhesions in 11 and noncommunicating effusions of the tendon sheath in six. Associated abnormalities of the rotator cuff were present in 16 while the seventeenth patient had glenohumeral synovitis without rotator cuff pathology. MR arthrograms correlated with arthroscopic findings in the joint but comparison was not possible in the intertubercular groove portion of the biceps tendon. None of the 10 patients with an arthroscopically normal biceps tendon showed any of the MR findings of bicipital tenosynovitis. CONCLUSION: Bicipital tenosynovitis is detectable by MR arthrography. In most cases it is an associated finding of rotator cuff abnormalities and likely to have a similar etiology. When lesions of the anterior rotator cuff are recognized, the biceps tendon should be scrutinized for inflammatory changes.

The rope ladder: an uncommon artifact and potential pitfall in MR arthrography of the shoulder.

OBJECTIVE: MR arthrograms were retrospectively reviewed for susceptibility artifacts induced by accidental injection of a small amount of gas when paramagnetic contrast solution was injected. A pitfall to interpretation, an unusual distribution of intraarticular gas into the sheath of the long biceps tendon that resembled a rope ladder, was observed and compared with findings of bicipital tenosynovitis. CONCLUSION: Intraarticular gas contamination during MR arthrography must be differentiated from intraarticular loose bodies and findings of bicipital tenosynovitis. Most reliable for the differential diagnosis are the different shapes and sizes of the gas-induced susceptibility artifacts on spin-echo and gradient-recalled echo images.

Diagnosis of tears in rotator-cuff-injuries.

Pathology of the rotator cuff is the cause of most common problems at the shoulder joint. Acute injuries are not as frequent as chronic cuff disease, but often they aggravate inflammatory or degenerative tendon alterations, even if they are of minor severity. Traumatic rotator cuff tears predominantly affect the supraspinatus tendon or the rotator interval. The subscapularis tendon is involved in anterior dislocations of the glenohumeral joint or in direct trauma. Plain film radiography still remains the base of all further imaging studies. If only full-thickness tears must be ruled out, double-contrast arthrography and ultrasound are acceptable imaging modalities. However, the former has a drawback in being invasive and does not detect partial tears at the bursal site of the cuff or rotator cuff tendinopathy, whereas the latter heavily depends on the experience of the radiologist and is restricted to the rotator cuff. Nowadays the most comprehensive imaging method is magnetic resonance (MR) imaging. MR imaging enables the detection or exclusion of complete rotator cuff tears with a reasonable accuracy and is also suitable to diagnose further pathologies of the shoulder joint. MR arthrography is valuable in the detection of subtle anatomic details and further improves the differentiation of rotator cuff diseases. Although in comparison MR imaging is still the most expensive imaging method, its high negative predictive value for the diagnosis of complete rotator cuff tears and its reliability evaluating different shoulder joint pathologies make it the preferred imaging modality.

Imaging the long head of biceps tendon--a pictorial essay emphasizing magnetic resonance.

Lesions of the long head of the bicepstendon (BT) are seen in association with tears of the rotator-cuff, particularly lesions of the subscapularis tendon and the rotator-interval. The frequency of positive MR-findings at the BT is approximately 25%. The pathologic alterations include complete medial luxation, subluxation and entrapment by the subscapularis tendon, tendinitis or tendovaginitis and lesions at the origin of the tendon at the superior labrum (superior labrum anterior to posterior (SLAP)--lesions). The imaging signs of BT pathology on MR include an abnormal course and position of the tendon, alterations in shape and changes in signal-intensity (SI), obliteration and thickening of the tendon-sheath. In long standing intra-articular BT rupture, neo-insertion of the tendon in the bicipital sulcus may ensue. The long BT needs to be visualized in transaxial, coronal oblique and sagittal oblique projections. Besides serving as stabilizer of the long head of biceps muscle, the BT is also an important stabilizer of the anterior joint capsule.

Solitary pulmonary nodules: MR evaluation of enhancement patterns with contrast-enhanced dynamic snapshot gradient-echo imaging.

PURPOSE: To evaluate the enhancement patterns of solitary pulmonary nodules (SPNs) with dynamic contrast-material-enhanced magnetic resonance (MR) imaging to differentiate between benign and malignant SPNs. MATERIALS AND METHODS: Twenty-eight patients with SPNs 30 mm or smaller in diameter were examined with pre- and postcontrast, electrocardiographically gated, T1-weighted spin-echo (SE) sequences and a snapshot gradient-echo (GRE) sequence after bolus injection of a paramagnetic contrast agent. For all SPNs (20 malignant, eight benign), the percentage increase in signal intensity (%SI) on the postcontrast T1-weighted SE images and the enhancement curves (%SI/sec) for the snapshot GRE measurements were established from regions of interest. RESULTS: Malignant nodules showed a higher increase of signal intensity during the first transit of the bolus of contrast material on the dynamic snapshot GRE images (malignant: median, 18.1 %SI/sec; range, 6.7-95.2 %SI/sec; benign: median, 2.3 %SI/sec; range, 0.1-8.1 %SI/sec) (P < .0001). Static T1-weighted SE measurements did not allow differentiation between malignant (median, 53.4 %SI; range 12.5-110.0 %SI) and benign (median, 33 %SI; range, 0.8-85.5 %SI) (P > .2) nodules on the basis of the degree of contrast enhancement. CONCLUSION: Dynamic contrast-enhanced MR measurements of tumor enhancement can provide additional information about the nature of SPNs.

[Basis of radiation protection]. / Grundlagen des Strahlenschutzes.

After an introduction, three selected contributions to the 10th Course on Radiation Protection held at the University Hospital of Basel are presented. The principles of radiation protection and new Swiss legislation are discussed as the basis for radiological protection. Ways are proposed of reducing radiation exposure while optimizing the X-ray picture with a minimum dose to patient and personnel. Radiation effects from low doses. From the beginning, life on this planet has been exposed to ionizing radiation from natural sources. For about one century additional irradiation has reached us from man-made sources as well. In Switzerland the overall annual radiation exposure from ambient and man-made sources amounts to about 4 mSv. The terrestrial and cosmic radiation and natural radionuclids in the body cause about 1.17 mSv (29%). As much as 1.6 mSv (40%) results from exposure to radon and its progenies, primarily inside homes. Medical applications contribute approximately 1 mSv (26%) to the annual radiation exposure and releases from atomic weapons, nuclear facilities and miscellaneous industrial operations yield less than 0.12 mSv (< 5%) to the annual dose. Observations of detrimental radiation effects from intermediate to high doses are challenged by observations of biopositive adaptive responses and hormesis following low dose exposure. The important question, whether cellular adaptive response or hormesis could cause beneficial effects to the human organism that would outweigh the detrimental effects attributed to low radiation doses, remains to be resolved. Whether radiation exerts a detrimental, inhibitory, modifying or even beneficial effect is likely to result from identical molecular lesions but to depend upon their quantity, localization and time scale of initiation, as well as the specific responsiveness of the cellular systems involved. For matters of radiation protection the bionegative radiation effects are classified as deterministic effects or stochastic effects respectively. The various histopathological reactions of tissues and organs following localized tissue irradiation, and the radiation syndromes following total body irradiation, constitute the deterministic effects. There will be a threshold below which deterministic effects do not appear and spontaneous incidences are not known. For low dose risk considerations deterministic effects are of no significance. Genetic effects and carcinogenesis are said to be stochastic effects. Characteristically the probability of stochastic effects increases with dose but the severity of the effects is independent of the dose. The shape of the dose-response relationship at intermediate to high dose levels is linear-quadratic. For exposure to low doses the response becomes linear, as is to be expected for a linear-quadratic function at low dose. No threshold is assumed for stochastic effects. The estimate of probability of fatal cancer by the ICRP is 4 x 10(-2) per Sv for the working population and 5 x 10(-2) per Sv for the total population. Their estimate of probability of serious hereditary disorders within the first two generations is 1 x 10(-2) per Sv. The highest probability coefficient is attributed to mental retardation following exposure in utero. Within the sensitive period at 8-15 weeks of gestation, a risk probability of 40 x 10(-2) per Sv is assumed but a threshold at 0.1 Sv is not excluded. Conclusions drawn from experiments, clinical observations and epidemiological studies following intermediate to high radiation exposures attribute a mutagenic and carcinogenic competence to all radiation doses. Microdosimetric considerations support this assumption. This conclusion cannot be confirmed experimentally nor by epidemiological studies of populations living under different conditions from natural sources of radiation. Nevertheless, a change in the present restrictive radiation protection policy does not yet appear appropriate.

Dynamic snapshot gradient-echo imaging of head and neck malignancies: time dependency and quality of contrast-to-noise ratio.

The purpose of this study was to evaluate the time dependency of the contrast-to-noise ratio (CNR) of head and neck malignancies during contrast-enhanced MR imaging. Then we would compare the CNR of dynamic snapshot gradient-echo (SGE) images with conventional spin-echo (SE) and fast spin-echo (FSE) sequences. Fifteen patients with squamous cell carcinomas were examined with T1W-SE, T2W-FSE, contrast-enhanced Gd-T1W-SE, and T1W-SGE sequences, the latter statically and contrast-enhanced dynamically. The CNR for all sequences and adjacent tissues was computed and the time to reach maximal CNR (Tmax) was determined for dynamic studies. The CNR was time dependent with two distinct Tmax at 6-18 and 60-160 s which corresponded to two different tumor enhancement patterns. Neither enhancement pattern correlated with distinct histologic findings or tumor grading. The CNR improved for the Gd-T1W-SE images. The improvement was statistically significant in relation to T1W-SE and Gd-T1W-SE images at the floor of the mouth and at the tongue base. The good CNR of the dynamic Gd-T1W-SGE measurements justifies further investigations of this method in order to improve tumor delineation.

Spin-echo and 3D gradient-echo imaging of the knee joint: a clinical and histopathological comparison.

OBJECTIVE: A clinical and histopathological comparison of 2D spin-echo (SE) and 3D gradient-echo (3DGE) sequences was undertaken for the knee joint. The purpose of the study was to evaluate the clinical results and to explain the different appearances of meniscal abnormalities on both 2DSE and 3DGE images. PATIENTS, MATERIALS AND METHODS: The clinical study comprised 45 patients with arthroscopically correlated MR imaging results. For the histopathological correlation, seven cadaveric knee joints were examined with the same 2DSE and 3DGE (FISP) imaging protocol and sliced in sagittal sections according to the MR images. Different stainings were used. RESULTS: For the detection of meniscal tears, accuracy (82.2%) and positive predictive value (70.7%) of the 3DGE sequence were limited due to a high number of false positive findings. Cartilaginous lesions were more easily visible on 3DGE than on 2DSE images (sensitivity: 63.1% vs. 52.6%, respectively). As in the clinical study, the meniscal signal abnormalities of the cadaveric knee joints were much more extensive on the 3DGE images than on the 2DSE images. The 3DGE findings correlated better with degenerative meniscal changes which were visible microscopically. CONCLUSION: The high sensitivity of the 3DGE sequence for degenerative meniscal changes explains the lack of specificity for the differentiation between meniscal degeneration and tears with this sequence. The MR grading system for meniscal lesions is of limited value for the evaluation of 3D FISP images.

[A comparative study of the imaging quality and picture dosage of a new conventional film-screen system for skeletal x-ray diagnosis]. / Vergleichende Untersuchung der Abbildungsqualität und Aufnahmedosis eines neuen konventionellen Film-Folien-Systems für die skelettal Röntgendiagnostik.

PURPOSE: This paper compares a new film-screen system (FSS) called INSIGHT Skeletal Imaging System with the previously used Lanex/T-MAT G FSS. MATERIAL AND METHODS: Using a Bronder phantom, measurements were made of dose, resolution and contrast. 135 skeletal phantom images were assessed in order of quality by six observers. RESULTS: Comparable high resolution film-screen combinations (FSC) showed similar geometric resolution. Comparing high intensifying screens, the new INSIGHT Skeletal Regular FSS showed better resolution than the Lanex medium FSC. Dose reduction for the INSIGHT Skeletal Imaging FSS was 29-56%. The new FSS showed image quality similar to high resolution screens but was significantly better when using high intensifying screens. CONCLUSION: The new INSIGHT Skeletal Imaging System can replace the Lanex/T-MAT G FFS by retaining quality but reducing radiation dose by 29-56%. Using the new high intensifying FSC, images showed in addition improved film quality.

Arterial pseudoaneurysm as a complication of percutaneous transhepatic biliary drainage: treatment by embolization.

We observed a serious arterial hemorrhage as a complication of percutaneous transhepatic biliary drainage (PTBD). The hemorrhage appeared during catheter placement for implantation of an endobiliary stent as a two-step procedure. It was caused by an arterial pseudoaneurysm and could be successfully treated by superselective embolization. Although there was a preexisting cavernous transformation of the portal vein no signs of liver cell necrosis appeared after embolotherapy. Vascular complications of PTBD will be discussed with regard to their frequency, possible etiology, ways to avoid them and their interventional therapy.

[Strategy for staging non-small cell bronchial carcinoma (NSCLC) with special reference to imaging procedures]. / Stagingstrategie beim nichtkleinzelligen Bronchialkarzinom (NSCLC) unter besonderer Berücksichtigung bildgebender Verfahren.

Imaging methods, especially CT and for specific questions MRI, are an essential part of diagnosis and staging of non-small cell lung cancer. They are effective methods for the detection of unresectable tumours and avoid the necessity for further invasive examinations and explorative thoracotomies. The judgement of lymph node size by CT suffers from a limited accuracy. Nevertheless, it allows guided bronchoscopical staging biopsies of enlarged mediastinal lymph nodes (> 1 cm) and, therefore, a selective indication of mediastinoscopy. CT scans of the thorax usually are extended to the adrenal glands and the liver to exclude metastasis. Extrathoracic scanning beyond the upper abdomen and bone scintigraphy should be restricted to patients with clinical indicators or symptoms. The combined application of imaging methods, bronchoscopy, and mediastinoscopy provides better selection of surgical candidates and hence reduces the rate of unresectable operations.

[Diagnostic possibilities of magnetic resonance tomography (MRT) and magnetic resonance angiography (MRA) in popliteal artery entrapment syndrome (PAES)]. / Diagnostische Möglichkeiten der Magnetresonanztomographie (MRT) und Magnetresonanzangiographie (MRA) beim Popliteal Artery Entrapment Syndrom (PAES).

MRT offers some advantages for morphological examinations of the fossa poplitea and appears to be superior in terms of multiplanar imaging over CT and duplex sonography for identifying a PAES. The method is always indicated when the diagnosis of PAES is suspected from the primary duplex sonography but the verification of the anatomic alteration is not conclusive. An MR angiography can, in principle, be carried out in the same session. On consideration of the currently presented cases, both inflow and phase-contrast MRA appear to be suited for examination. However, a sufficient detail resolution is only achieved by use of a surface coil which then makes assessment of the contralateral side and the lower leg arteries impossible. Specially fitted coils which allow a double-sided representation of sufficient image quality may, however, make conventional angiography unnecessary in future.

[The findings and value of computed tomography in pleural empyema]. / Befunde und Stellenwert der Computertomographie beim Pleuraempyem.

Chest radiographs and CT images of 25 patients with pleural empyemas were compared retrospectively with those of 20 patients with pleural exudates and transudates in order to determine criteria for differential diagnosis and to define the place of CT in the diagnosis of pleural empyemas. The sign which was most suggestive of an empyema on a chest radiograph was an encapsulated effusion in an atypical position (18/25); this was found in only 4 out of 20 exudates and in none of the transudates. On CT, changes in the pleura, the subcostal tissues and the configuration and position of the fluid were suggestive of an empyema. In nearly all patients with a pleural empyema there was thickening and increased contrast uptake of the parietal pleura (22/25) and thickening and increased density oft the subcostal tissues (23/25). Usually, empyemas were encapsulated and biconvex (20/25). None of the patients with pleural transudates showed any of these changes. In the presence of some pleural exudates, pleural (14/20) or thoracic (11/20) changes were noted. In part, these changes were due to previous treatment (sclerotherapy) or tumour infiltration (7/20). An attempt to correlate the CT findings with changes in the pleura and subcostal tissues with the clinical empyema stages I-III, according to Light, showed that CT was unable to distinguish between early and late empyemas. Consequently, diagnostic aspiration remains necessary for correct treatment.