Potential of iodine-123 metaiodobenzylguanidine single-photon emission tomography to detect abnormal functional status of the pulmonary neuroadrenergic system in irradiated lung

The potential of iodine-123 metaiodobenzylguanidine (MIBG) to detect functional abnormalities of the pulmonary neuroadrenergic system (PNS) in irradiated lung areas (ILAS) was preliminarily explored using single-photon emission tomography (SPET). The subjects included five healthy subjects and a total of 31 patients with peripheral-type lung cancer treated by radiation; 15 patients (group A) had received a dose of less than 36 Gy (mean ± SD: 28.2 ±6.2 Gy), and 16 patients (group B) had received a higher dose (mean ± SD: 51.2 ± 3.5 Gy) at the time of examination. MIBG SPET scans aquired 15 min and 3 h after injection were used to measure the MIBG uptake ratio (count ratio of the ILA to the contralateral non-ILA) and the clearance rate [percentage of (early counts – delayed counts)/early counts] from the ILAs without noticeable abnormal opacities on chest computed tomography scan. Lung perfusion changes were also assessed by technetium-99m macroaggregated albumin SPET. By contrast to the homogeneous MIBG uptake in the lungs of the healthy subjects, MIBG uptake was folcally decreased in correspondence with the ILAs in all patients, including 11 patients (73.3%) of group A with relatively preserved lung perfusion. The reduction MIBG uptake was significant (P<0.0001), and the MIBG clearance rate from the ILAs was also significantly faster than the clearance rates from the normal lungs and contralateral non-ILAs (both P<0.01). Group B patients showed significantly lower MIBG uptake and faster clearance from the ILAs than group A patients (P<0.001 and P<0.05, respectively), although there was no significant difference in the clearance from the non-ILAs. Overall, MIBG uptake/clearance from the ILAs correlated significantly with the radiation dose in the 31 patients (r = –0.656; P<0.0001 and r = 0.387; P<0.05, respectively). Perfusion changes were inversely correlated with the clearance from the ILAs (r = –0.432, P<0.05), but did not correlate with MIBG uptake. These preliminary results suggest that MIBG may have the potential to be a marker of abnormal functional status of the PNS produced by irradiation and may facilitate investigation of irradiation lung injury independently of morphological or lung perfusion changes. Received 11 December 1998 and in revised form 10 February 1999     

Serial histopathological changes in irradiated guinea pig lung receiving conventional fractionated and hyperfractionated irradiation.

PURPOSE: To determine serial histopathological differences in guinea pig lungs receiving the same total dose as clinically used between conventional fractionated and hyperfractionated irradiation. METHODS AND MATERIALS: The guinea pigs received 80 Gy in 40 daily fractions of 2 Gy each (conventional fractionation), 80 Gy in 80 fractions of 1 Gy each twice a day (hyperfractionation), 81 Gy in 27 daily fractions of 3 Gy each (conventional fractionation), or 81 Gy in 54 fractions of 1.5 Gy each twice a day (hyperfractionation). We evaluated the histopathological changes of irradiated guinea pig lungs at 1, 2, 3, 6, 9, and 12 months after irradiation. RESULTS: The guinea pig lungs that received 81 Gy in 27 daily fractions showed histopathological changes of inflammation including formation of lymph follicles after 6 months. The lungs which received 81 Gy in 54 fractions showed similar but slightly less pronounced changes than those that received 81 Gy in 27 daily fractions. The guinea pig lungs of other groups showed no histopathological changes during the observation period. CONCLUSION: In hyperfractionated irradiation the damage to the guinea pig lung is quantitatively less than that occurring as a result of conventional fractionated irradiation of the same total dose.     

Quantitative CT detects progression in COPD patients with severe emphysema in a 3-month interval

Chronic obstructive pulmonary disease (COPD) is characterized by variable contributions of emphysema and airway disease on computed tomography (CT), and still little is known on their temporal evolution. We hypothesized that quantitative CT (QCT) is able to detect short-time changes in a cohort of patients with very severe COPD. Two paired in- and expiratory CT each from 70 patients with avg. GOLD stage of 3.6 (mean age = 66 ± 7.5, mean FEV1/FVC = 35.28 ± 7.75) were taken 3 months apart and analyzed by fully automatic software computing emphysema (emphysema index (EI), mean lung density (MLD)), air-trapping (ratio expiration to inspiration of mean lung attenuation (E/I MLA), relative volume change between − 856 HU and − 950 HU (RVC856–950)), and parametric response mapping (PRM) parameters for each lobe separately and the whole lung. Airway metrics measured were wall thickness (WT) and lumen area (LA) for each airway generation and the whole lung. The average of the emphysema parameters (EI, MLD) increased significantly by 1.5% (p < 0.001) for the whole lung, whereas air-trapping parameters (E/I MLA, RVC856–950) were stable. PRMEmph increased from 34.3 to 35.7% (p < 0.001), whereas PRMNormal decrased from 23.6% to 22.8% (p = 0.012). WT decreased significantly from 1.17 ± 0.18 to 1.14 ± 0.19 mm (p = 0.036) and LA increased significantly from 25.08 ± 4.49 to 25.84 ± 4.87 mm2 (p = 0.041) for the whole lung. The generation-based analysis showed heterogeneous results. QCT detects short-time progression of emphysema in severe COPD. The changes were partly different among lung lobes and airway generations, indicating that QCT is useful to address the heterogeneity of COPD progression. • QCT detects short-time progression of emphysema in severe COPD in a 3-month period. • QCT is able to quantify even slight parenchymal changes, which were not detected by spirometry. • QCT is able to address the heterogeneity of COPD, revealing inconsistent changes individual lung lobes and airway generations.     

Clinical outcome of stereotactic body radiotherapy of 54 Gy in nine fractions for patients with localized lung tumor using a custom-made immobilization system

Purpose The aim of this study was to investigate the clinical outcome of stereotactic body radiotherapy (SBRT) of 54 Gy in nine fractions for patients with localized lung tumor using a custom-made immobilization system. Methods and materials The subjects were 19 patients who had localized lung tumor (11 primaries, 8 metastases) between May 2003 and October 2005. Treatment was conducted on 19 lung tumors by fixed multiple noncoplanar conformal beams with a standard linear accelerator. The isocentric dose was 54 Gy in nine fractions. The median overall treatment time was 15 days (range 11–22 days). All patients were immobilized by a thermo-shell and a custom-made headrest during the treatment. Results The crude local tumor control rate was 95% during the follow-up of 9.4–39.5 (median 17.7) months. In-field recurrence was noted in only one patient at the last follow-up. The Kaplan-Meier overall survival rate at 2 years was 89.5%. Grade 1 radiation pneumonia and grade 1 radiation fibrosis were observed in 12 of the 19 patients. Treatment-related severe early and late complications were not observed in this series. Conclusion The stereotactic body radiotherapy of 54 Gy in nine fractions achieved acceptable tumor control without any severe complications. The results suggest that SBRT can be one of the alternatives for patients with localized lung tumors. Part of this work was presented at the 65th annual meeting of the Japan Radiological Society, April 2006     

Pulmonary postmortem computed tomography of bacterial pneumonia and pulmonary edema in patients following non-traumatic in-hospital death

In this study, we compared the postmortem computed tomography (PMCT) findings among nonpathological lungs, lungs with bacterial pneumonia, and lungs with pulmonary edema in patients following non-traumatic in-hospital death. We studied 104 consecutive adult patients (208 lungs) who died in our tertiary care hospital and underwent PMCT and pathological autopsy (both within 2.5 days after death), and were pathologically diagnosed with nonpathological lungs, bacterial pneumonia, and pulmonary edema. Thirteen pulmonary features were assessed on the CT scans. We also examined the association between the time elapsed since death and the pulmonary findings. We observed increased lung opacities with horizontal plane formation, diffuse opacities, diffuse bronchovascular bundle thickening, symmetric opacities to the contralateral lung, and decreased segmental opacities with time elapsed since death (Cochran–Armitage test for trend). Multiple logistic regression revealed that the presence of opacities without horizontal plane formation or centrilobular opacities, and the absence of diffuse bronchovascular bundle thickening were associated with histopathological pneumonia, whereas the presence of opacities with horizontal plane formation, diffuse opacities, and interlobular septal thickening were associated with histopathological pulmonary edema. In conclusion, specific pulmonary PMCT findings increased with time elapsed since death, and some lung findings may facilitate the diagnosis of bacterial pneumonia and pulmonary edema.     

Yield of head CT in the alcohol-intoxicated patient in the emergency department

We aimed to determine the yield of positive head computed tomography (CT) findings among suspected alcohol-intoxicated patients presenting to the emergency department (ED). Our secondary aim was to determine if elderly intoxicated patients were more likely to have an intracranial injury. We identified patients suspected of alcohol intoxication who underwent CT scanning in the ED over a 4-year period. Pre-determined data elements including demographics, diagnosis, and disposition were extracted using a pre-formatted data sheet by blinded abstractors. “Positive” CT was defined as evidence of any type of intracranial hemorrhage. A total of 2,671 subjects with suspected alcohol intoxication and a head CT were identified. Fifty out of the 2,671 (1.9%) had a positive CT. Among CT scans of elderly (≥60 years of age) subjects, 15/555 (2.7%, 95% CI = 1.4–4.1%) were positive compared with 35/2,116 (1.7%, 95% CI = 1.1–2.2%) among those <60 years of age (p = 0.11). The yield of positive head CT among alcohol-intoxicated patients was low, at 1.9%. An age cutoff of 60 years in this population did not predict a significantly higher positive rate.     

Evaluation of lung injury after three-dimensional conformal stereotactic radiation therapy for solitary lung tumors: CT appearance

PURPOSE: To evaluate the computed tomographic (CT) appearance of tumors and lung injury in patients who have undergone stereotactic radiation therapy (SRT) for solitary lung tumors. MATERIALS AND METHODS: Twenty-seven patients with primary lung cancer and four with metastatic lung cancer who underwent SRT for solitary lung tumors were enrolled for evaluation. SRT was delivered by using a three-dimensional conformal technique with a stereotactic body frame. A total dose of 48 Gy was administered in four fractions during a period of 2 weeks. After SRT, follow-up CT images were obtained every 2-3 months. Radiation-induced pulmonary injuries were classified into four patterns on CT images. The minimal lung dose to areas demonstrating pulmonary injury at CT was evaluated, and the correlation between the dose and the percentage volume of the whole lung irradiated by more than 20 Gy in total (V20) was assessed by using Spearman rank correlation. RESULTS: Tumor shrinkage continued for 2-15 months after SRT. Asymptomatic changes in the irradiated lung were noted at CT in all patients within 2-6 months (median, 4 months) after SRT. As the pattern at pulmonary CT changed, patchy consolidation was more predominantly seen as an acute change than were slight homogeneous increase in opacity, discrete consolidation, or solid consolidation; solid consolidation was the more predominantly seen late change. The minimal lung dose to the area demonstrating pulmonary injury in each patient ranged between 16 and 36 Gy (median, 24 Gy). The dose was significantly (P <.001) inversely correlated with the V20 in each patient. CONCLUSION: The reaction to SRT of the lungs seems similar to the reaction to conventional radiation therapy.     

Computed chest tomography in an animal model for decompression sickness: radiologic, physiologic, and pathologic findings

This study was conducted to investigate the early pulmonary effects of acute decompression in an animal model for human decompression sickness by CT and light microscopy. Ten test pigs were exposed to severe decompression stress in a chamber dive. Three pigs were kept at ambient pressure to serve as controls. Decompression stress was monitored by measurement of pulmonary artery pressure and arterial and venous Doppler recording of bubbles of inert gas. Chest CT was performed pre- and postdive and in addition the inflated lungs were examined after resection. Each lung was investigated by light microscopy. Hemodynamic data and bubble recordings reflected severe decompression stress in the ten test pigs. Computed tomography revealed large quantities of ectopic gas, predominantly intravascular, in three of ten pigs. These findings corresponded to maximum bubble counts in the Doppler study. The remaining test pigs showed lower bubble grades and no ectopic gas by CT. Sporadic interstitial edema was demonstrated in all animals – both test and control pigs – by CT of resected lungs and on histologic examination. A severe compression–decompression schedule can liberate large volumes of inert gas which are detectable by CT. Despite this severe decompression stress, which led to venous microembolism, CT and light microscopy did not demonstrate changes in lung structure related to the experimental dive. Increased extravascular lung water found in all animals may be due to infusion therapy. Received: 7 December 1998; Revision received: 2 June 1999; Accepted: 9 June 1999     

White matter changes on magnetic resonance imaging following whole-brain radiotherapy for brain metastases

Purpose The purpose of this study was to evaluate white matter (WM) abnormalities induced by WBRT. Materials and methods Twenty-four patients (11 men and 13 women; age range 38–74 years, median 60 years) who survived for more than 1 year after completion of WBRT (radiation dose range 30–40 Gy, median 35 Gy) at our institution between January 2000 and June 2003 were followed up with magnetic resonance (MR) scans for 11–51 months (median 19 months). We evaluated WM changes attributable to WBRT as grade 0–6 and assessed possible contributing factors by statistical analysis. Results WM changes were found in 20 patients: Eight were assessed as grade 2, three as grade 3, and nine as grade 5. In total, 12 patients developed grade 3 or higher WM changes. Age (<60 vs ≥60 years), sex, radiation dose (≤35 vs >35 Gy), chemotherapy (with CDDP vs without CDDP), biologically effective dose (≤120 vs >120 Gy1), and head width (<16.3 vs ≥16.3 cm) were found not to be relevant to the incidence or severity of the WM changes. Conclusion Long-term survivors who have under-gone WBRT may have a higher incidence of WM abnormalities.     

Prevalence and correlates of pulmonary emphysema in smokers and former smokers. A densitometric study of participants in the ITALUNG trial

We assessed with computed tomography (CT) densitometry the prevalence of emphysema in 266 (175 men and 91 women; mean age 64 ± 4 years) smokers and former smokers enrolled in the ITALUNG trial of lung cancer screening with low-dose thin-slice CT. Whole-lung volume and the relative area at −950 Hounsfield units (RA₉₅₀) and mean lung attenuation (MLA) in 1 of every 10 slices (mean, 24 slices per subject) were measured. Lung volume, MLA and RA950 significantly correlated each other and with age. Average RA950 >6.8% qualifying for emphysema was present in 71 (26.6%) of 266 subjects, with a higher prevalence in men than in women (30.3% vs 19.8%; p = 0.003). Only in smokers was a weak (r = 0.18; p = 0.05) correlation between RA950 and packs/year observed. In multiple regression analysis, the variability of RA950 (R2 = 0.24) or MLA (R2 = 0.34) was significantly, but weakly explained by age, lung volume and packs/year. Other factors besides smoking may also have a significant role in the etiopathogenesis of pulmonary emphysema. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Automated classification of normal and pathologic pulmonary tissue by topological texture features extracted from multi-detector CT in 3D

To provide a novel, robust algorithm for classification of lung tissue depicted by multi-detector computed tomography (MDCT) based on the topology of CT-attenuation values and to compare discriminative results with densitometric methods. Two hundred seventy-five cubic volumes of interest (VOI, edge length 40 pixels) were obtained from MDCT chest CT (isotropic voxel size, edge length 0.6 mm) of 21 subjects with and without pathology (emphysema, fibrosis). All VOIs were visually consensus-classified by two radiologists. Texture features based on the Minkowski functionals (MF) as well as on the CT attenuation values are determined. Classification results of both approaches were assessed by receiver-operator characteristic and discriminant analysis. By densitometric (topological) parameters, normal and abnormal VOIs were distinguished with an area under the curve ranging from 0.78 to 0.85 (0.87 to 0.96). Correlation between both groups of parameters was non-significant (p ≥ 0.36). By combined information of densitometric and topological quantities, the radiologists’ ratings were reproduced for 92% of VOIs, ranging from 85.7% (fibrosis) to 98% (normal VOIs). Our method performs well for identification of VOIs containing abnormal lung-tissue. Combined information of densitometry and topology increases the number of correctly classified VOIs further. When extended to CT data depicting whole lungs, topological analysis may allow to enhance density-based analysis and improve monitoring texture changes with progression of pulmonary disease.     

Assessment of lobar perfusion in smokers according to the presence and severity of emphysema: preliminary experience with dual-energy CT angiography

The purpose of the study was to assess pulmonary perfusion on a lobar level in smokers using dual-energy computed tomography (CT). Forty-seven smokers and ten non-smokers underwent a dual-energy multi-detector CT angiogram of the chest that allowed automatic quantification of emphysema and determination of the iodine content at the level of the microcirculation (i.e. “perfusion imaging”). Emphysema was present in 37 smokers and absent in ten smokers. Smokers with an upper lobe predominance of emphysema (n = 8) had: (1) significantly lower attenuation enhancement values in the upper lobes compared with smokers without emphysema; (2) the lobes with the most severe emphysematous changes had a statistically significantly higher percentage of emphysema (p = 0.0001) and lower mean attenuation enhancement values (p = 0.0001) than the ipsilateral lobes with less severe emphysema, matching parenchymal destruction; (3) a correlation was found between the difference in percentage of emphysema between the upper and lower lobes and the difference in attenuation attenuation enhancement values in the corresponding lobes (p = 0.0355; r = −0.54). Regional alterations of lung perfusion can be depicted by dual-energy CT in smokers with predominant emphysema.     

PET imaging with [<Superscript>18</Superscript>F]3′-deoxy-3′-fluorothymidine for prediction of response to neoadjuvant treatment in patients with rectal cancer

Purpose Positron emission tomography (PET) using ¹⁸F-labelled 3′-deoxy-3′-fluorothymidine (FLT) was assessed for therapy monitoring in patients with rectal cancer undergoing neoadjuvant chemoradiotherapy. Methods Ten patients with locally advanced rectal cancer were included and underwent long-course preoperative chemoradiotherapy (total dose 45 Gy, 1.8 Gy/day, concomitant 250 mg/m² 5-fluorouracil) followed by surgery. FLT-PET was performed prior to chemoradiotherapy, 2 weeks after initiation of chemoradiotherapy and preoperatively (3–4 weeks post chemoradiotherapy). FLT uptake was correlated with histopathological tumour regression and changes in T stage. Results Mean tumour FLT uptake was 4.2±1.0 SUV before therapy and decreased significantly to 2.9 ± 0.6 SUV 14 days after initiation of chemoradiotherapy (−28.6% ± 10.7%, p = 0.005). The preoperative scan showed a further decrease to 1.9 ± 0.4 SUV (−54.7% ± 7.6%, p = 0.005). However, the degree of change in FLT uptake 2 weeks after initiation and after completion of neoadjuvant therapy did not correlate with histopathological tumour regression. Conclusion FLT-PET did not seem to be a promising method for assessment of tumour response in the studied chemoradiotherapy regimen in patients with rectal cancer.     

Cardiac imaging using 256-detector row four-dimensional CT: preliminary clinical report

Purpose Along with the increase of detector rows on the z-axis and a faster gantry rotation speed, the spatial and temporal resolutions of the multislice computed tomography (CT) have been improved for noninvasive coronary artery imaging. We investigated the feasibility of the second specification prototype 256-detector row four-dimensional CT for assessing coronary artery and cardiac function. Materials and methods The subjects were five patients with coronary artery disease. Contrast medium (40–60 ml) was intravenously administered at the rate of 3–4 ml/s. The patient's whole heart was scanned for 1.5 s to cover at least one cardiac cycle during breathholding without electrocardiographic gating. Parameters used were 0.5 mm slice thickness, 0.5 s/rotation, 120 Kv, and 350 mA, with a half-scan reconstruction algorithm (temporal resolution 250 ms). Twenty-six transaxial datasets were reconstructed at intervals of 50 ms. Results The assessability of the coronary arteries in AHA segments 1, 2, 3, 5, 6, 7, 9, and 11 was visually evaluated, resulting in 29 of 32 (90.9%) segments being assessable. Functional assessment was also performed using animated movies without banding artifacts in all cases. Conclusions The 256-detector row four-dimensional CT can assess the coronary artery and cardiac function using data during 1.5 s without banding artifacts.     

Impact of chest CT on the clinical management of immunocompetent emergency department patients with chest radiographic findings of pneumonia

The purpose of this study is to assess the impact on clinical decision making of chest computed tomography (CT) in immunocompetent emergency department (ED) patients with chest radiographic (CXR) findings of pneumonia. We retrospectively identified 1,373 patients from our ED who underwent chest CT between 7/05 and 6/06. Report of CXR within 24 h before CT were reviewed to identify patients with findings of pneumonia. The following were the exclusion criteria: recommendation of CT on CXR report and immunocompromised status on chart review. Fifty-one patients met the inclusion criteria: 26 women and 25 men, with a mean age of 60 (range 29–103) years. Age- and sex-matched controls from the ED with CXR findings of pneumonia who did not undergo CT were identified. Charts were reviewed for clinical presentation, management, and follow-up. Patient and control groups were compared using Fisher exact and paired Student’s t tests. The patients were sicker than the controls with more signs and symptoms including auscultation abnormalities, 64 (33 of 51) vs 47% (24 of 51), abnormal sputum 32 (16 of 51) vs 0%, hypoxemia 22 (11 of 51) vs 2% (1 of 51), weight loss, 20 (10 of 51) vs 4% (2 of 51), and night sweats, 16 (8 of 51) vs 2% (1 of 51; p < 0.05 each). Clinical management, (based on CT findings in 31% [16 of 51]), was more extensive for patients than controls: antibiotics initiated 82 (41 of 51) vs 47% (24 of 51), antibiotics changed 29 (15 of 31) vs 0%, procedures performed 24 (12 of 51) vs 0%, and mean length of stay was 8 days vs less than 1 (p < 0.05, each). Sixteen percent (8 of 51) of the patients had alternative/additional diagnosis based on CT: pulmonary embolism, lung cancer, hypersensitivity pneumonitis, multiple myeloma, renal cell carcinoma, small bowel obstruction, lung nodule, and endobronchial mass (n = 1, each). Eight percent (4 of 51) of the patients and no controls were diagnosed with tuberculosis (p = 0.06). Immunocompetent ED patients with CXR findings of pneumonia who underwent chest CT were sicker than those who were not imaged with CT. Chest CT was often useful in guiding therapy or providing an alternative diagnosis.     

Diagnostic imaging of post-irradiation changes in the chest

Thirty-nine patients were studied with regard to post-irradiation changes in the chest. Twenty of these were reviewed retrospectively and 19 studied prospectively. All patients had chest radiographs and computed tomography (CT) of the chest following radiotherapy. Nineteen also had ventilation and perfusion studies of the lung, including single photon emission computed tomography (SPECT) and these were correlated with the chest radiographs and computed tomography. The majority showed abnormalities on computed tomography, the commonest being areas of lung opacification and evidence of volume loss. Several patients also showed a reduction in the size of pulmonary vessels. In most but not all, the changes were also seen on the chest radiographs. Abnormalities were not confined to the radiation fields, the vascular changes being present in large areas of lung which had not been directly irradiated. The structural and functional abnormalities correlated well as shown by ventilation and perfusion scintigraphy. However, single photon emission computed tomography was more sensitive than planar scintigraphy in showing perfusion defects, and it also showed some defects in areas of lung which appeared normal on computed tomography and the chest film. Computed and photon emission tomography were considerably more sensitive than chest radiography in showing the changes due to irradiation. The chest radiograph is clearly an insensitive indicator of post-irradiation change in the lung. Functional abnormalities are more profound and extensive than the chest film suggests, even when it is positive. There are clear implications for the planning of radiotherapy fields affecting the chest in patients who have good prospects of long-term survival. The maximum damage is related to irradiation of the hilum or mediastinum and this should be avoided wherever possible.     

Late Effects of Thoracic Irradiation in Children

Purpose:  To summarize the literature regarding the late effects of radiotherapy to the thorax in childhood and adolescence with special emphasis on cardiac and pulmonary impairment. Material and Methods:  The literature was critically reviewed using the PubMed^? database with the key words “late effects”, “late sequelae”, “child”, “childhood”, “adolescence”, “radiation”, “radiotherapy”, “thorax”, “lung”, “heart”, and “pulmonary”. Results:  17 publications dealing with radiation-induced pulmonary and cardiac late sequelae in children could be identified and were analyzed in detail. 29 further publications with additional information were also included in the analysis. Pulmonary function impairment after mediastinal irradiation arose in one third of all pediatric patients, even when treatment was performed with normofractionated lower doses (15–25 Gy). Whole lung irradiation was regularly followed by pulmonary function impairment with differing rates in several reports. However, clinically symptomatic function impairment like dyspnea was less frequent. Irradiation of up to 25 Gy (single doses ≤ 2 Gy) to the heart showed little or no cardiac toxicity in analyses of irradiated children (median follow-up 1.3–14.3 years). Doses of > 25 Gy (single doses ≤ 2–3.3 Gy) led to several cardiac dysfunctions. However, new data from adults with longer follow-up may indicate threshold doses as low as 1 Gy. Impairment of skeletal growth, breast hypoplasia, and secondary malignancy were further potential late sequelae. Conclusion:  Several retrospective reports described radiation-associated late sequelae in children. However, there is still a lack of sufficient data regarding the characterization of dose-volume effects.      

Altered kinetics of 123I-IMP in irradiated rabbit lungs.

Radiation-induced alteration of intrapulmonary kinetics of 123I-IMP was investigated in 11 rabbits receiving a 50 Gy dose of radiation to one lung. In all 13 examinations of these rabbits, 3-17 weeks following radiation, the delayed images of 123I-IMP lung scintigrams showed abnormal accumulation in the irradiated lungs. The time-activity curves of the irradiated lung following injection of 123I-IMP had shallower downslopes of both the initial fast phase and the following slow phase than those of the non-irradiated lung. Finally the radioactivity of the irradiated lung exceeded that of the normal lung. The altered intrapulmonary kinetics of 123I-IMP in the irradiated lung was clearly confirmed. 99Tcm-MAA lung perfusion scintigrams showed reduced uptake in the irradiated lungs; the uptake decreased with time following radiation. Pulmonary arterial perfusion was considered to influence the distribution and kinetics of 123I-IMP, however, those of 123I-IMP did not reflect only the pulmonary arterial perfusion observed by 99Tcm-MAA scintigrams. Chest radiography and histological studies revealed a relatively slight change or injury of the irradiated lung in these rabbits. These results indicate that this agent could be useful in detecting and assessing early lung injury induced by radiation, and will give us pathological information in addition to lung perfusion in the peripheral area where the large 99Tcm-MAA molecule cannot reach.     

银翘温胆汤干预大鼠放射性肺纤维化的初步实验研究

目的应用大鼠放射性肺纤维化模型观察银翘温胆汤对早期放射性肺炎和晚期肺纤维化的干预效果。探讨其在治疗放射性肺纤维化中的作用机制,以期为临床应用提供实验依据。方法将雄性大鼠45只随机分为对照组(0Gy+生理盐水)、照射组(20Gy+生理盐水)、银翘温胆汤组(20Gy+中药),单次6MV X线20Gy照射大鼠双肺,建立放射性肺纤维化模型。分别于2、4、6周时各处死5只大鼠取肺组织,进行HE染色观察肺组织病理变化,检测肺系数,用免疫组化法测转化生长因子-β1(TGF-β1)的表达。结果照射组大鼠肺损伤明显,肺系数、肺纤维化和TGF-β1的表达较对照组明显增高(P<0.05),而银翘温胆汤组大鼠比照射组的肺充血、出血、渗出性改变及肺泡壁增厚、肺纤维化程度减轻,且肺系数和TGF-β1的表达有一定程度的下降。结论银翘温胆汤对大鼠早期放射性肺炎和肺纤维化有一定程度的保护作用,其机制可能是通过抑制TGF-β1表达,使放射性肺炎及肺纤维化病变减轻。     

Preoperative assessment of thymic veins on multidetector row CT: optimization of contrast material volume

Purpose Preoperative localization of the thymic veins is considered important to prevent intraoperative severe bleeding prior to video-assisted thoracoscopic thymectomy. The purpose of this study was to determine the optimal dose of contrast material for preoperative CT imaging for the detection of thymic veins on the basis of patient weight. Materials and methods The records of 31 patients who underwent thymectomy were examined retrospectively. All patients were scanned using an eight-channel multidetector-row computed tomography (CT) scanner at 1.25 mm collimation and a 0.625-mm reconstruction interval. CT scans were obtained after injection of 300 mg I/ml nonionic contrast material at a rate of 2 ml/s. A 90-ml contrast bolus was used for the first 16 consecutive patients (group I), and a 150-ml bolus was used for the following 15 patients (group II). The scan delay was 60 s and 90 s in groups I and II respectively. Two independent radiologists who were blinded to the surgical results evaluated the number of thymic veins observed on preoperative CT, which was later correlated with the actual number of thymic veins clipped during surgery. The responses were analyzed with respect to contrast amount by single bolus and per kilogram of body weight. Results Thymic veins were correctly detected in 9 of 16 (56%) patients in group I and 14 of 15 (93%) patients in group II. Thymic vein detection was significantly better in patients who received the ≥2.0 ml/kg contrast medim compared to those who received the 1.00–1.99 ml/kg medium (P < 0.05). Conclusion An intravenous contrast material volume of 2 ml/kg (300 mg I/ml) is appropriate for the identification of thymic veins on prethymectomy CT.