[11 beta-hydroxysteroid dehydrogenases: key enzymes in the action of mineralocorticoids and glucocorticoids].
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11-beta-Hydroxysteroid Dehydrogenases↗
Biomedical subjects
S Diederich
Publications and source records attributed to S Diederich.
Detection of pulmonary nodules with overlapping vs non-overlapping image reconstruction at spiral CT.
The aim of this study was to analyze whether overlapping image reconstruction increases numbers of pulmonary nodules detected at helical CT. Forty-eight helical CT scans (21 with a slice thickness of 10 mm; 27 with a slice thickness of 5 mm) of patients with known pulmonary nodules were reconstructed both with overlapping and non-overlapping image reconstruction. Two readers recorded number and size of pulmonary nodules as well as diagnostic confidence. With overlapping image reconstruction each reader diagnosed more pulmonary nodules (slice thickness 10 mm: +24.0 and +26.7%, both p < 0.01; slice thickness 5 mm: +9.5 and +11.9%, both not significant) and more "definite" nodules (slice thickness 10 mm: +20.3%, p < 0.05, and +30.8%, p < 0.005; slice thickness 5 mm: +18.0 and +17.0%, both p < 0.05). Nodules diagnosed with overlapping image reconstruction only were almost exclusively smaller than the slice thickness. The increase in number of nodules detected was not associated with a decrease in diagnostic confidence. Overlapping image reconstruction improves detection of pulmonary nodules smaller than the slice thickness at spiral CT.
Adolescent↗
Pulmonary nodules: experimental and clinical studies at low-dose CT.
PURPOSE: To compare the number of pulmonary nodules detected at helical low- and standard-dose computed tomography (CT) and to investigate the diagnostic value of low-dose CT with a radiation exposure equivalent to that used at chest radiography. MATERIALS AND METHODS: Two radiologists recorded pulmonary nodules at standard-dose (250 or 100 mA, pitch of 1; 200 mA, pitch of 2) or low-dose CT (50 or 25 mA, pitch of 1 or 2) in five postmortem specimens and 75 patients. Nodules were assessed by size (5 mm or smaller, 6-10 mm, or larger than 10 mm) and by diagnostic confidence ("definite nodule," "definite lesion, not classic nodule," or "questionable lesion, possibly representing a vessel") with the Wilcoxon signed rank test. Artifacts depicted at low-dose CT were recorded. RESULTS: There were no statistically significant differences in the number of nodules detected at standard- or low-dose CT except in nodules 5 mm or smaller that were assessed as definite nodules at standard- or low-dose CT (25 mA, pitch of 2) (472 vs 397, P < .05). Artifacts that possibly interfered with nodule detection were observed exclusively at CT with 25 mA and a pitch of 2. CONCLUSION: Pulmonary nodules were detected reliably at CT with 50 mA and pitch of 2 or with 25 mA and a pitch of 1. However, further reduction of the dose to that used at chest radiography was associated with a significant decrease in the number of nodules 5 mm or smaller that were detected, possibly due to artifacts.
Adult↗
Progesterone metabolism in the human kidney and inhibition of 11beta-hydroxysteroid dehydrogenase type 2 by progesterone and its metabolites.
Progesterone binds with high affinity to the mineralocorticoid (MC) receptor, but confers only very low agonistic MC activity. Therefore, progesterone is a potent MC antagonist in vitro. Although progesterone reaches up to 100 times higher plasma levels in late pregnancy than aldosterone, the in vivo MC antagonistic effect of progesterone seems to be relatively weak. One explanation for this phenomenon could be local metabolism of progesterone in the human kidney, similar to the inactivation of cortisol to cortisone by the 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2. We studied the metabolism of progesterone in the human kidney in vitro and found reduction to 20alpha-dihydro (DH)-progesterone as the main metabolite. Ring-A reduction to 5alpha-DH-progesterone, 20alpha-DH-5alpha-DH-progesterone, and 3beta,5alpha-tetrahydro (TH)-progesterone was also documented. We further showed for the first time that 17-hydroxylation of progesterone (17alpha-OH-progesterone, 17alpha-OH, 20alpha-DH-progesterone), normally localized in the adrenals and the gonads, occurs in the human adult kidney. We found no formation of deoxycorticosterone from progesterone in the human adult kidney. Using human kidney cortex microsomes, we tested the inhibitory potency of progesterone and its metabolites on the 11beta-HSD type 2. The most potent inhibitor was progesterone itself (IC50 = 4.8 x 10(-8) mol/L), followed by 5alpha-DH-progesterone (IC50 = 2.4 x 10(-7) mol/L), 20alpha-DH-progesterone, 3beta,5alpha-TH-progesterone, 17alpha-OH-progesterone, and 20alpha-DH-5alpha-DH-progesterone (IC50 between 7.7 x 10(-7) mol/L and 1.3 x 10(-6) mol/L). The least potent inhibitor was 17alpha-OH,20alpha-DH-progesterone. In addition to progesterone metabolism by the kidney, the inhibition of 11beta-HSD type 2 by progesterone and its metabolites could be a second explanation for the weak MC-antagonist activity of progesterone in vivo. Inhibition of 11beta-HSD type 2 leads to an increase of intracellular cortisol in a way that the local equilibrium between the MC agonist cortisol and the antagonist progesterone is shifted to the agonist side.
11-beta-Hydroxysteroid Dehydrogenases↗
Helical CT of pulmonary nodules in patients with extrathoracic malignancy: CT-surgical correlation.
OBJECTIVE: Our aim was to assess the sensitivity of helical CT for revealing pulmonary nodules. Thoracotomy with palpation of the deflated lung, resection, and histologic examination of palpable nodules was used as the gold standard. SUBJECTS AND METHODS: Thirteen patients underwent helical CT (slice thickness, 5 mm; reconstruction intervals, 3 mm and 5 mm; interpreted by two independent observers). Subsequently, patients underwent unilateral (n = 6) or bilateral (n = 7) surgical exploration, and CT-surgical correlation of 20 lungs was performed. RESULTS: Ninety nodules were resected (61 were smaller than 6 mm; 13 were 6-10 mm; 11 were larger than 10 mm; in five nodules, the size was not recorded at surgery). Sixty-nine nodules were located in the pulmonary parenchyma and 21 in the visceral pleura. Of the 90 lesions, 43 (48%) were found on histology to represent metastases. For lesions detected by at least one observer, the sensitivity of helical CT was 69% for intrapulmonary nodules smaller than 6 mm, 95% for intrapulmonary nodules larger than or equal to 6 mm, and 100% for histologically proven intrapulmonary metastases larger than or equal to 6 mm. For lesions smaller than or equal to 10 mm, sensitivity was better using a reconstruction interval of 3 mm rather than of 5 mm. CONCLUSION: In this study, the sensitivity of helical CT exceeded the sensitivity of conventional CT in previous reports. However, because of limitations in the detection of intrapulmonary nodules smaller than 6 mm and of pleural lesions, complete surgical exploration should remain the procedure of choice in patients undergoing pulmonary metastasectomy. Preoperative helical CT should be used to guide the surgeon to lesions that are difficult to palpate.
Adult↗
ESDIR. Fast cross-sectional imaging (CT and MRI). Münster (Germany) 25-27 September 1997.
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Congresses as Topic↗
Aspergillus infection of the respiratory tract after lung transplantation: chest radiographic and CT findings.
The objective of our study was to assess radiographic and CT findings in lung transplant patients with evidence of Aspergillus colonization or infection of the airways and correlate the findings with clinical, laboratory, bronchoalveolar lavage, biopsy and autopsy findings. The records of 189 patients who had undergone lung transplantation were retrospectively reviewed for evidence of Aspergillus colonization or infection of the airways. Aspergillus was demonstrated by culture or microscopy of sputum or bronchoalveolar lavage fluid or histologically from lung biopsies or postmortem studies in 44 patients (23 %). Notes and radiographs were available for analysis in 30 patients. In 12 of the 30 patients (40 %) chest radiographs remained normal. In 11 of 18 patients with abnormal radiographs pulmonary abnormalities were attributed to invasive pulmonary aspergillosis (IPA) in the absence of other causes for pulmonary abnormalities (8 patients) or because of histological demonstration of IPA (3 patients). In these 11 patients initial radiographic abnormalities were focal areas of patchy consolidation (8 patients), ill-defined pulmonary nodules (2 patients) or a combination of both (1 patient). In some of the lesions cavitation was demonstrated subsequently. At CT a "halo" of decreased density was demonstrated in some of the nodules and lesion morphology and location were shown more precisely. Demonstration of Aspergillus from the respiratory tract after lung transplantation does not necessarily reflect IPA but may represent colonization of the airways or semi-invasive aspergillosis. The findings in patients with IPA did not differ from those described in the literature in other immunocompromised patients, suggesting that surgical disruption of lymphatic drainage and nervous supply or effects of preservation and transport of the transplant lung do not affect the radiographic appearances.
Adult↗
A very high dose dexamethasone suppression test for differential diagnosis of Cushing's syndrome.
OBJECTIVE: The high-dose dexamethasone (dex) suppression test of cortisol secretion (8 x 2 mg dex over two days or 8 mg overnight) is a mainstay in the differential diagnosis of Cushing's syndrome (CS). In some patients with pituitary Cushing's disease (CD), however, plasma cortisol is not suppressed to < 50% of control by 8 mg of dex. We therefore hypothesized that a higher dose of dex might produce more effective suppression of cortisol secretion in CD. DESIGN AND SUBJECTS: We routinely tested the diagnostic efficacy of a very high dose of dex (32 mg, i.e. 4 x 8 mg in 24 hours) in comparison with the 8 mg overnight dex test in a population of patients with CD, in which an unusually high percentage was refractory to 8 mg dex. End points were the suppression of plasma cortisol, plasma ACTH and urinary free cortisol (UFC) to < 50% of control. Corticotrophin releasing hormone (human CRH) tests were also performed. RESULTS: Eleven out of 26 (11/26) patients with CD (42%), among them six with pituitary macro-adenomas, failed to show suppression of plasma cortisol after 8 mg dex. Five out of 19 patients (26%) with CD failed to suppress after 32 mg dex. Only 3/19 (16%) failed to suppress UFC after 32 mg dex. In nonpituitary CS (n = 11), only one patient with macro-nodular adrenal hyperplasia showed significant suppression of plasma cortisol, but not UFC, after 32 mg dex. ACTH suppression after 8 or 32 mg dex was often less pronounced than that of cortisol and was of no diagnostic value. Cortisol stimulation by > or = 23% after hCRH injection differentiated 100% of patients with CD from other forms of CS. CONCLUSION: In this series, the hCRH test was the most reliable test for the differential diagnosis of Cushing's syndrome. The 32 mg dexamethasone test with measurement of urinary free cortisol was clearly superior to the 8 mg test and to other aspects of the very high dose dexamethasone test. It can be recommended for 'non-suppressible' patients with ACTH-dependent Cushing's syndrome and can be performed on outpatients.
ACTH Syndrome, Ectopic↗
Comparison of low and high dose corticotropin stimulation tests in patients with pituitary disease.
Tetracosactin [corticotropin-(1-24)] is used for clinical testing of adrenocortical responsiveness. The usual dose [high dose test (HDT)] is 250 micrograms. With this test, patients with mild secondary adrenal insufficiency are usually not identified, thus putting them at risk of an adrenal crisis in stressful situations. It was recently reported that a tetracosactin test with approximately 1 micrograms [low dose test (LDT)] identifies patients with mild forms of pituitary-adrenal insufficiency. We performed both the HDT and the LDT in 35 control subjects and in 44 patients with pituitary disease, mostly pituitary tumors. In these patients, more sensitive reference tests for evaluating the pituitary-adrenal axis (insulin-induced hypoglycemia, metyrapone, and CRH tests) were also performed. In the HDT, plasma cortisol was measured 30 and 60 min after tetracosactin injection; in the LDT (0.5 microgram/m2 body surface area), plasma cortisol was measured 20, 30, 40, 50, and 60 min postinjection. In 6 control subjects, tetracosactin plasma levels were also measured after injection. In the HDT, the correlation between 30 and 60 min cortisol levels was extremely high (r = 0.991; P < 0.0001), but the correlation of the LDT with the HDT at 30 min was also highly significant (r = 0.948; P < 0.0001). The lower normal limit of cortisol responses (means of controls minus 2 SD) at 30 min was lower in the LDT by 3.1 micrograms/dL (85 nmol/L) than in the HDT. Compared with the reference tests, the diagnostic sensitivities of the HDT and the LDT were almost identical. Both tests identified patients with moderately to severely pathological insulin and metyrapone tests, but not those with slightly pathological reference tests. In the HDT, plasma tetracosactin rose to more than 60,000 pg/mL shortly after injection. In the LDT, it rose to 1,900 pg/mL. Both concentrations stimulate cortisol (supra-) maximally. Together, these data show that in pituitary disorders the results of the LDT and the HDT are almost identical. Plasma tetracosactin levels in the LDT still rise to levels that maximally stimulate the adrenal. Tetracosactin testing with low or high doses cannot generally replace the more expensive and cumbersome insulin or metyrapone tests.
Adult↗
Metabolism of dexamethasone in the human kidney: nicotinamide adenine dinucleotide-dependent 11beta-reduction.
Recently, two distinct isoenzymes of 11beta-hydroxysteroid-dehydrogenase (11beta-HSD) have been cloned and characterized in several species: The isoenzyme 11beta-HSD-I is widely distributed, bidirectional, prefers NADP(H) and has a low substrate affinity. The isoenzyme 11beta-HSD-II seems to exclusively oxidize physiological glucocorticoids, uses NAD as cosubstrate, has high substrate affinity, and is only found in mineralocorticoid target tissues and the placenta. Synthetic steroids fluorinated in position 9, however, are rapidly reduced by human kidney cortex slices. We attempted to find out which isoenzyme is responsible for this unexpected reductase activity. We studied the 11beta-HSD activity towards cortisol (F)/cortisone (E) and dexamethasone (D)/11-dehydro-dexamethasone (DH-D) in microsomes prepared from human kidney cortex. For the reaction E to F (not for DH-D to D!), glucose-6-phosphate and glucose-6-phosphate-dehydrogenase had to be added as a NADH/NADPH-regenerating system. Oxidation of F to E: NAD was the exclusively used cosubstrate; the affinity [Michael's constant (Km) for F = 25.5 nmol/L] and the maximum velocity (Vmax = 22.9 nmol/mg/min) were high. Reduction of E to F: Without the NADH/NADPH-regenerating system, this reaction was very slow. With this system, the Km value for E was in the nanomolar range (80.6 nmol/L) and the Vmax value was very low (0.88 nmol/mg/min). The reaction was clearly NADH-preferring. For the steroid pair F/E, the quotient Vmax(oxidation)/Vmax(reduction) (=26) demonstrates an equilibrium far on the 11-keto side. Oxidation of D to DH-D: With NAD as the only used cosubstrate, the kinetic analysis is compatible with the existence of two different NAD-dependent isoenzymes: Km for D = 327 nmol/L, Vmax = 53.5 nmol/mg/min and Km for D = 81.2 nmol/L; Vmax = 20.4 nmol/mg/min. Reduction of DH-D to D: The maximum velocity was higher than that of all other reactions tested: Vmax = 226.0 nmol/mg/min. The reaction was exclusively NADH-dependent; the Km value for DH-D was 68.4 nmol/L. For D/DH-D, the ratio Vmax(oxidation)/Vmax(reduction) was 0.24, demonstrating a shift to reductase activity with the reaction equilibrium far on the 11-hydroxy side. The reaction F to E was inhibited by E, DH-D, and D in a concentration-dependent manner. In conclusion, the cosubstrate dependence, the Km value of the oxidation of F and the product inhibition are in good correspondence with data for the cloned human 11beta-HSD-II. The NADH-dependent 11beta-reduction of E and especially of DH-D are inconsistent with the dogma of an unidirectional 11beta-HSD-II. The preference of D for the reductase reaction in human kidney slices is probably caused by the fluor atom in position 9, is catalyzed by 11beta-HSD-II, and leads to an activation of 11-DH-D to D in the human kidney.
11-beta-Hydroxysteroid Dehydrogenases↗
Evidence for isoforms of 11 beta-hydroxysteroid dehydrogenase in the liver and kidney of the guinea pig.
In the human and in rodents like the rat and mouse, the liver enzyme 11 beta-hydroxysteroid dehydrogenase type I (11 beta-HSD-I) is a functional oxidoreductase preferring NADP+/NADPH as cosubstrate, while the renal isoenzyme (11 beta-HSD-II) prefers NAD+ as cosubstrate, and seems to be a pure oxidase and protects the tubular, mineralocorticoid (MC) receptor from occupancy by cortisol and corticosterone. We studied the enzyme kinetics of 11 beta-HSDs in kidney and liver microsomes of the guinea pig, a species whose zoological classification is still a matter of debate. With a fixed concentration of 10(-6) mol/l cortisol, liver and kidney microsomes preferred NAD+ to NADP+ (10(-3) mol/l) for the conversion to cortisone. Kidney microsomes converted cortisol to cortisone with K(m) values of 0.64 mumol/l and 9.8 mumol/l with NAD+ and NADP+ as cosubstrates respectively. The reduction of cortisone to cortisol was slow with kidney microsomes, but could be markedly enhanced by adding an NADH/NADPH regenerating system: with NADPH as preferred cosubstrate, the approximate K(m) was 7.2 mumol/l. This indicated the existence of both isoenzymes in the guinea pig kidney. Liver microsomes oxidized cortisol to cortisone with similar K(m) and Vmax values for NAD+ to NADP+ as cosubstrates (K(m) of 4.3 mumol/l and 5.0 mumol/l respectively). The NAD+ preference for the oxidation of 10(-6) mol/l cortisol described above may be due to a second, NAD(+)-preferring 11 beta-HSD with a K(m) of 1.4 mumol/l. In contrast to the kidney, liver microsomes actively converted cortisone to cortisol with a preference for NADPH (K(m): 1.2 mumol/l; Vmax: 467 nmol/min per mg protein). Thus, the main liver enzyme is similar to the oxidoreductase of other species (11 beta-HSD-I) and is also present in the kidney, while the main kidney enzyme is clearly NAD(+)-preferring. This kidney enzyme (analogous to 11 beta-HSD-II of other species) seems to be suitable for the protection of the MC receptor from the high free plasma cortisol levels of the guinea pig.
11-beta-Hydroxysteroid Dehydrogenases↗
[Successful multimodal therapy of a locally advanced non-small-cell bronchial cancer].
HISTORY AND CLINICAL FINDINGS: A chest radiogram, performed on a 60-year-old man with unproductive cough for 3 months, showed a space-occupying lesion in the right upper lobe, and breath sounds were diminished in this area. He had been a heavy smoker. His general condition and nutritional state were good. INVESTIGATIONS: Computed tomography, skeletal scintigraphy, bronchoscopy with biopsy and mediastinoscopy established the diagnosis of a locally advanced non-small-cell bronchial carcinoma (stage IIIB or T2N3M0). TREATMENT AND COURSE: Combined adjuvant treatment was begun in the hope of improving the median survival time of 8 months predicted for this tumour stage. After two cycles of a combined chemotherapy scheme (ifosfamide, carboplatin, etoposide) he received hyperfractionated-accelerated radiotherapy (total dose 45 Gy; 1.5 Gy twice daily) together with carboplatin and vindesine. This was followed by a right upper lobectomy with lymphadenectomy. Full remission was confirmed in both the resected specimen and the lymph nodes. The patients remains free of tumour 30 months after the diagnosis. CONCLUSION: Neoadjuvant treatment can significantly improve the prognosis of non-small-cell bronchial carcinoma in stage III. Such patients should therefore be treated according to the appropriate study protocol, if possible.
Antineoplastic Combined Chemotherapy Protocols↗
[Bronchiolitis obliterans with organizing pneumonia: differential diagnosis of pneumonia refractory to antibiotics].
HISTORY AND FINDINGS: A previously healthy 58-year-old woman was admitted with rapidly worsening dyspnoea, dry cough and subfebrile temperature. Chest radiogram showed spotty infiltrations, especially in the bases of both lungs. She was dyspnoic with mild tachypnoea (24/min) and mild cyanosis of the lips. Fine, non-resonant rales were heard over the middle and lower lobes bilaterally. INVESTIGATIONS: Erythrocyte sedimentation rate was markedly raised (97/110 mm), arterial oxygen partial pressure slightly decreased (45 mm Hg), CO2 partial pressure was 32 mm Hg. Bronchoalveolar lavage was unremarkable. TREATMENT AND COURSE: Because of the respiratory impairment broad antibiotic treatment was at once commenced empirically with gentamycin, cefotaxim, erythromycin, rifampicin and fluconazole. As the response was poor, a transbronchial lung biopsy was performed. This merely showed nonspecific lymphoplasmacellular bronchitis. An open biopsy then revealed bronchiolitis obliterans with organizing pneumonia (BOOP). Treatment with initially 75 mg prednisone daily quickly brought about improvement and the patient was entirely well after 6 months. CONCLUSION: The described constellation of history and clinical as well as radiological findings should strongly suggest BOOP. With adequate treatment the prognosis is excellent.
Anti-Bacterial Agents↗
Interobserver variation in the diagnosis of bronchiectasis on high-resolution computed tomography.
The purpose of our study was to determine interobserver variation in the analysis of high-resolution computed tomography (HRCT) in the lungs of patients with clinically suspected bronchiectasis. HRCT scans of 88 patients were analysed independently by three radiologists with variable experience in thoracic radiology using a subjective scoring system to record bronchi as normal, mildly abnormal or severely abnormal. The presence, severity and distribution of bronchial dilatation and bronchial wall thickening were recorded. Kappa values were calculated for assessment of interobserver agreement. Agreement between the three readers was good for the detection of bronchiectasis (kappa 0.78) and assessment of its severity (0.68), detection of bronchial wall thickening (0.64) and moderately good for the assessment of its severity (0.58) on a per-patient basis. When individual lobes were analysed, agreement was moderately good for the detection of abnormal bronchi (0.59). Agreement on the extent of abnormal bronchi using five categories was only fair (0.39), but was good when differences of one category were ignored (0.63). Interobserver variation with HRCT in suspected bronchiectasis appears satisfactory for comparative studies.
Adolescent↗
[Low dose computerized tomography of the thorax. Experimental and clinical studies].
INTRODUCTION: Computed tomography is a significant source of medical radiation exposure for populations in Europe. Reduced radiation exposure may be possible with modern CT scanners with an image quality that while less good than before remains acceptable for clinical purposes. The lung appears particularly well suited to investigation with low-dose CT owing to the high contrast between normal and diseased pulmonary parenchyma. METHODS: We analysed the diagnostic accuracy of different low-dose CT protocols for the detection of pulmonary nodules using inflation-fixed isolated postmortem lung specimens in a chest phantom. In a comparative patient study diagnostic accuracies of standard-dose CT (120 kV, 250 mAs; slice thickness 10 mm, pitch 1) and low-dose CT (120 or 140 kV, 50 mAs; slice thickness 5 or 10 mm, pitch 1 or 2) were assessed. RESULTS: Preliminary results suggest that low-dose CT protocols with radiation exposure of 10-20% of that with standard-dose CT an reliably depict soft tissue density pulmonary nodules with a diameter of more than 5 mm and can also demonstrate smaller nodules equally well is many cases. CONCLUSIONS: Low-dose CT may frequently be an adequate imaging procedure in a given clinical setting, particularly in young patients with benign disease.
Humans↗
[Radiation exposure in low dose computerized tomography of the thorax].
Computed tomography accounts for a high percentage of the populations exposure to radiation. Every possible means of reducing patient exposure must be considered. Exposure reduction will be most appropriate for organs with large absorption differences, since the accompanying decrease in signal-to-noise ratio will have a smaller effect. It has been shown in the literature that high-contrast details in the lung can be depicted, even with the lowest exposure rates. Therefore, experimental data are presented by means of thermoluminescence dosimetry and calculations using conversion factors to determine the technical parameters to be adopted for achieving the effective equivalent dose close to that of a conventional chest X-ray in two projections. With helical CT (pitch 2, 50 mAs, 120 kV, 5-mm slice thickness) it was possible to reduce the equivalent dose from 9.6 mSv to 0.6 mSv, which is comparable with the exposure in a conventional chest X-ray, measured to be 0.2 mSv.
Equipment Design↗
[Phenomenology of pulmonary HRCT. Definitions, differential diagnosis and clinical relevance].
High-resolution computed tomography (HRCT) has proved to be the imaging technique of choice for the lung in numerous studies, allowing precise depiction of normal pulmonary anatomy-including the lobular architecture-as well as relevant pathologic changes. Its sensitivity, specificity and accuracy in this respect are markedly superior, not only to chest radiography, but also to conventional CT. Guidelines for standardized assessment and interpretation of HRCT findings have not been established in the German literature. The purpose of this paper was to develop a systematic classification of pulmonary HRCT findings based on the appearance of morphologic abnormalities (descriptive classification) and their relationship to anatomic structures of pulmonary parenchyma (anatomic classification). Reticular, nodular, and non-reticular/non-nodular densities, as well as lucencies, can be differentiated. Abnormalities of the pleural space are discussed separately. Following the presentation of typical CT findings, morphologic correlation and differential diagnosis are discussed. In addition, we point out indications and specific features of the clinical value of the technique.
Diagnosis, Differential↗
[Diagnostic imaging in bronchiectases. Value of CT and HRCT].
Various diseases can cause bronchiectasis as a result of inflammatory bronchial wall damage. The diagnosis is based on imaging techniques, which are also required to assess the extent and localization of dilated bronchi and possible causes. Chest radiography only occasionally allows the diagnosis of bronchiectasis (Fig.2) and is usually not a sufficient basis for therapeutic decisions (Fig. 1a), but it is important for follow-up studies. Bronchography (Fig.1b) was considered the diagnostic procedure of choice in suspected bronchiectasis for decades. Being an invasive procedure, it has recently been almost completely replaced by computed tomography (CT), which can also demonstrate associated pulmonary abnormalities (Fig.6) in addition to visualizing the bronchi. CT diagnosis of bronchiectasis is based on the demonstration of bronchial dilatation relative to the adjacent pulmonary artery (Figs. 4, 5, 7-9), lack of bronchial tapering (Figs. 3, 4, 10) and visualization of bronchi in the lung periphery (Figs. 3, 5, 8, 10). In suspected bronchiectasis high-resolution scans should be obtained during inspiration. Contiguous, thicker slices or scans taken during expiration may be required in particular cases.
Bronchiectasis↗