[Multi-slice CT angiography of thoracic pathology: particularities and new indications]. / Angioscanographie multicoupe en pathologie thoracique: particularités et indications nouvelles.

This review consists in three main topics. At this time, technology does not allow for optimal functional and morphological evaluation of the cardiac chambers. However, a precise pretherapeutic map of the systemic supply of the lung can be non invasively obtained.

[Interpretation of thoracic radiographs re-examined and corrected with tomodensitometry]. / L'interprétation d'une radiographie thoracique revue et corrigée par la tomodensitométrie.

To our knowledge, conventional chest radiography is not likely to become obsolete or disappear from the daily practice of medical imaging. As such, it is important to insure that chest radiographs are acquired using optimal technique. Evaluation of chest radiograph findings must be comprehensive and the art of reading chest radiographs must be well thought to physicians in training. Chest radiography is characterized by the projection of tridimensional anatomical structures and disease processes onto a two-plane radiographic film. Correlation with cross-sectional data obtained from CT may greatly enhance the understanding and interpretation of conventional chest radiographs. Indeed, review of CT images facilitates anatomical understanding of the segmental and subsegmental anatomy, of the superior segments of the lower lobes and of the three dimensional orientation of the fissures. CT also has improved the understanding of some chest radiography findings. Careful review of findings at chest radiography is helpful to optimize CT acquisition protocols in order to reduce some of the pitfalls of CT and improve detection of specific processes that could otherwise be poorly demonstrated or overlooked. Chest radiographs can sometimes detect diseases or abnormalities that are difficult to demonstrate at CT.

[Optimal screening tool for thoracic diseases: chest X ray or CT?]. / Outil optimal de dépistage en pathologie thoracique: radiographie ou scanner?

There are good reasons to believe that screening of lung parenchymal diseases by CT is superior to chest radiographs. Nevertheless, conventional chest radiography often remains the first examination performed for evaluation of thoracic diseases and, irrespective of clinical indication, it plays an important role in screening procedures. The interpretation methodology of a chest radiograph in a screening condition is reviewed. Specific attention to poor detectability zones is emphasized and a check-list is proposed, mainly to reduce the risk of overlooking lesions. Techniques, indications and respective diagnostic values for both chest radiography and CT scan are analyzed and applied to the screening of lung cancer, asbestos exposure and tuberculosis.

Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation.

The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = 1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33% in group 1 (range 22-40%) and 34% in group 2 (range 26-40%). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86%). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32% in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91% in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70% in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use.

Peripheral pulmonary arteries: how far in the lung does multi-detector row spiral CT allow analysis?

PURPOSE: To analyze the influence of multi-detector row spiral computed tomography (CT) on identification of peripheral pulmonary arteries. MATERIALS AND METHODS: Peripheral pulmonary arteries were analyzed on optimally opacified contrast material-enhanced spiral CT angiograms in 30 patients devoid of pleuroparenchymal disease who underwent scanning with multi-detector row CT (collimation, 4 x 1 mm; pitch, 1.7-2.0; scanning time, 0.5 second). Two series of scans were systematically generated from each data set, 1.25-mm-thick (group 1) and 3-mm-thick (group 2) sections, leading to the analysis of 600 segmental (20 arteries per patient), 1,200 subsegmental (40 arteries per patient), 2,400 fifth-order (80 arteries per patient), and 4,800 sixth-order (160 arteries per patient) pulmonary arteries in each group. RESULTS: Multi-detector row CT with reconstructed scans of 1.25-mm-thick sections (group 1) allowed (a) analysis of a significantly higher percentage of subsegmental arteries (94% in group 1 vs 82% in group 2; P <.001) and (b) a significantly higher percentage of fifth- and sixth-order arteries, respectively, identified in 74% and 35% of cases in group 1 and 47% and 16% in group 2 (P <.001). The causes for inadequate depiction of subsegmental branches in group 1 were partial volume effect (43%), anatomic variants (39%), and cardiac (17%) and respiratory (1%) motion artifacts. CONCLUSION: Multi-detector row CT with reconstructed scans of 1.25-mm-thick sections enables accurate analysis of peripheral pulmonary arteries down to the fifth order on spiral CT angiograms.

Thin-section CT finding in 250 volunteers: assessment of the relationship of CT findings with smoking history and pulmonary function test results.

PURPOSE: To evaluate the frequency and morphologic characteristics of air trapping in volunteers with various smoking habits. MATERIALS AND METHODS: Two hundred fifty volunteers (133 women, 117 men; mean age, 39 years), including 144 smokers, 47 ex-smokers, and 59 nonsmokers, prospectively underwent inspiratory and expiratory high-spatial-resolution computed tomography (CT) and pulmonary function tests (PFTs). The frequency and characteristics of air trapping were evaluated according to the population's smoking habits and PFT results. RESULTS: The overall frequency of air trapping was 62% (155 of 250 subjects). Lobular air trapping was depicted in 117 (47%) of 250 subjects, without significant differences among smokers (n = 91), ex-smokers (n = 33), and nonsmokers (n = 31) (P =.118). Segmental and lobar air trapping (38 [15%] of 250) were more frequent among smokers (24 [26%] of 91) and ex-smokers (nine [27%] of 33) (P <.001). No relationship was found between air trapping and functional indexes of small-airway disease when the CT pattern of air trapping was considered. The strongest relationship between CT abnormalities and functional alterations at the small-airways level was between inspiratory CT features of bronchiolitis: ground-glass opacity, ill-defined micronodules, bronchiolectasis, and air flow at low lung volumes. CONCLUSION: Whereas a significant relationship was observed between segmental and lobar air trapping and cigarette consumption, lobular air trapping was not found to reflect functional impairment at the small-airways level.