Percentage Of Total Lung Volume Research Articles

Functional Image-Guided Radiotherapy Planning in Respiratory-Gated Intensity-Modulated Radiotherapy for Lung Cancer Patients With Chronic Obstructive Pulmonary Disease

To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values of less than than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung. Two respiratory-gated radiotherapy plans (70 Gy/35 fractions) were designed and compared in each patient as follows: Plan A was an anatomical IMRT or VMAT plan based on the total lung; Plan F was a functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (percentage of total lung volume irradiated with ≥20 Gy [V20], and mean dose of total lung [MLD]) of the two plans were compared. V20 was lower in Plan F than in Plan A (mean 1.5%, p = 0.025 in IMRT, mean 1.6%, p = 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p = 0.083 in IMRT, mean 0.5 Gy, p = 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. Functional IGRT planning based on LAA in respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.

The Value of Pulmonary Contusion Volume Measurement With Three-Dimensional Computed Tomography in Predicting Acute Respiratory Distress Syndrome Development

This study reports the value of accurate pulmonary contusion (PC) volume measurement with 3-dimensional computed tomography (CT) in predicting acute respiratory distress syndrome (ARDS) development. The study enrolled all patients who were diagnosed with PC on admission by CT and had a chest Abbreviated Injury Score (AIS) exceeding 2 between January 1, 2010, and October 31, 2010. PC volume was measured from 3-dimensional reconstructions of admission chest CTs and expressed as a percentage of total lung volume. Admission data were prospectively collected. The independent predictor of ARDS development was established. The accuracy and value of the predictors were analyzed, and the influence of PC volume percentage on clinical outcomes was demonstrated. The average PC volume percentage was 21.86% ± 13.90% (range, 5.6% to 61.0%), which was inconsistently correlated with the admission partial pressure of oxygen/fraction of inspired oxygen ratio (R(2) = 0.083). ARDS was diagnosed in 26 patients (43.3%) and pneumonia in 21 (35.0%). The admission partial pressure of oxygen/fraction of inspired oxygen ratio (p = 0.003) and PC volume percentage (p = 0.01) were independent predictive factors of ARDS development. Patients with a PC volume percentage exceeding the best cutoff of 21.5% were defined as the severe PC group. The partial pressure of oxygen/fraction of inspired oxygen ratio, the needed maximal positive end-expiratory pressure level, and ARDS incidence between the severe group and the general group was significantly different (p <.05). Pulmonary contusion volume measured using 3-dimensional CT is feasible in emergency departments and helpful to identify patients at high-risk for ARDS.

High-dose 3-dimensional conformal radiotherapy with concomitant vinorelbine plus carboplatin in patients with non-small cell lung cancer: A feasibility study

The aim of this study was to evaluate the feasibility of high-dose 3-dimensional conformal radiotherapy (3DCRT) (70 Gy) with concomitant vinorelbine (NVB) plus carboplatin (CBP) chemotherapy in patients with non-small cell lung cancer (NSCLC). Patients with advanced NSCLC were treated with 3-dimensional conformal radiotherapy in conventional fractionation: 2 Gy/fraction, 1 fraction/day, 5 fractions/week; total dose 70 Gy. The radiotherapy planning of every case had met the following conditions: the percentage of total lung volume receiving 20 Gy (V20) ≤30% and the percentage of total lung volume receiving 30 Gy (V30) ≤20%. Chemotherapy was commenced on the first day of radiotherapy: NVB 25 mg/m(2), day 1 and day 8, CBP at AUC of 5 mg/ml(-1).min(-1), day 8, repeated for 28 days, two concomitant cycles during radiotherapy, and not more than 4 cycles following radiotherapy. A total of 37 patients were recruited and each of them completed the entire radiation procedure. No Grade V toxicity was observed within the group. The hematological toxicity rates were: Grade III/IV neutropenia was observed in 18.9% (7/37) of cases, Grade III/IV thrombocytopenia in 8.1% (3/37) of cases, but no cases of Grade III/IV anemia were noted. For non-hematological toxicities the rates were: Grade III radiation pneumonitis, 8.1% (3/37) of cases; Grade III radiation esophagitis, 13.5% (5/37); but no cases of Grade IV/V non-hematological toxicities. High-dose 3DCRT also achieved a favorable efficacy: the complete response (CR) rate was 13.5% (5/37) and the partial response (PR) rate was 64.9% (24/37). The total response (CR+PR) rate was 78.4% (29/37). The median survival time was 12 months and the 1-year overall survival rate was 45.1%. Given that 35% of patients in the study had stage IV disease, the survival results were comparable with other similar studies. In conclusion, in our small-sample exploratory study, the high-dose regimen of 70 Gy using 3DCRT with concomitant NVB plus CBP was feasible for patients with NSCLC. Further evaluation of this regimen is ongoing in a prospective controlled phase II trial.

Extrapolation from ten sections can make CT-based quantification of lung aeration more practicable

Clinical applications of quantitative computed tomography (qCT) in patients with pulmonary opacifications are hindered by the radiation exposure and by the arduous manual image processing. We hypothesized that extrapolation from only ten thoracic CT sections will provide reliable information on the aeration of the entire lung. CTs of 72 patients with normal and 85 patients with opacified lungs were studied retrospectively. Volumes and masses of the lung and its differently aerated compartments were obtained from all CT sections. Then only the most cranial and caudal sections and a further eight evenly spaced sections between them were selected. The results from these ten sections were extrapolated to the entire lung. The agreement between both methods was assessed with Bland-Altman plots. Median (range) total lung volume and mass were 3,738 (1,311-6,768) ml and 957 (545-3,019) g, the corresponding bias (limits of agreement) were 26 (-42 to 95) ml and 8 (-21 to 38) g, respectively. The median volumes (range) of differently aerated compartments (percentage of total lung volume) were 1 (0-54)% for the nonaerated, 5 (1-44)% for the poorly aerated, 85 (28-98)% for the normally aerated, and 4 (0-48)% for the hyperaerated subvolume. The agreement between the extrapolated results and those from all CT sections was excellent. All bias values were below 1% of the total lung volume or mass, the limits of agreement never exceeded ± 2%. The extrapolation method can reduce radiation exposure and shorten the time required for qCT analysis of lung aeration.

Pulmonary Contusion in the Pediatric Population

Pulmonary contusion in the adult population is an independent risk factor for respiratory failure, ventilator associated pneumonia, and acute respiratory distress syndrome. Pilot studies in adults note an increased risk when volume of pulmonary contusion exceeds 20 per cent of total lung volume. The purpose of this study was to determine if children with pulmonary contusion suffer the same morbidity as adults. From January 2005 to May 2007, all trauma patients ages 3 to 18-years-old were assessed for CT evidence of pulmonary contusion. Children were excluded if injury included confounding variables, which could result in respiratory failure independent of contusion status. CT images were reviewed and pulmonary contusion was calculated as a percentage of total lung volume. Outcomes including need for invasive ventilation, pneumonia, and development of oxygenation problems were recorded. Data collected included patient age, Injury Severity Score, arterial blood gas findings, and number of rib fractures. Twenty-six patients met criteria for the study with a mean age of 13.35 years and mean Injury Severity Score of 24. The mean percentage of pulmonary contusion was 19.81 per cent. No patients required intubation. Pediatric pulmonary contusion does not carry the same morbidity as noted in the adult population. Invasive airway management is rarely required.

Critical Evaluation of Pulmonary Contusion in the Early Post-Traumatic Period: Risk of Assisted Ventilation

This study attempts to accurately quantify pulmonary contusion and predict those patients most likely to require assisted ventilation early in their hospital course. Patients admitted to a Level I trauma center were evaluated for pulmonary contusion by helical CT scan. Scans were reviewed by a single radiologist who attempted to accurately quantify contusion as a percentage of total lung volume. These patients were then followed for 48 hours in an attempt to use CT measurements of contusion to predict those that would require assisted ventilation early in their hospital course. After using numerous exclusion criteria, 152 patients were included in the study. Of these, 31 patients (20%) required assisted ventilation within 48 hours of hospital admission. Twenty per cent pulmonary contusion proved to be a highly predictive variable leading to need for assisted ventilation. Of patients sustaining <20 per cent contusion, only 7 of 92 (8%) required assisted ventilation versus 24 of 60 (40%) sustaining >20 per cent contusion. Pulmonary contusion is a significant injury especially when contusion volume exceeds 20 per cent of total lung volume. With accurate measurement of contusion, we can identify those patients at high risk of requiring assisted ventilation early in their hospital course.

Adding Ipsilateral V 20 and V 30 to Conventional Dosimetric Constraints Predicts Radiation Pneumonitis in Stage IIIA–B NSCLC Treated With Combined-Modality Therapy

To determine lung dosimetric constraints that correlate with radiation pneumonitis in non-small-cell lung cancer patients treated with three-dimensional radiation therapy and concurrent chemotherapy. Between June 2002 and December 2006, 97 patients with locally advanced non-small-cell lung cancer were treated with concomitant radiochemotherapy. All patients underwent complete three-dimensional treatment planning (including dose-volume histograms), and patients were treated only if the percentage of total lung volume exceeding 20 Gy (V(20)) and 30 Gy (V(30)), and mean lung dose (MLD) had not exceeded the constraints of 31%, 18%, and 20 Gy, respectively. The total and ipsilateral lung dose-volume histogram parameters, planning target volume, and total dose delivered were analyzed and correlated with pneumonitis incidence. If dose constraints to the total lung were respected, the most statistically significant factors predicting pneumonitis were the percentage of ipsilateral lung volume exceeding 20 Gy (V(20)ipsi), percentage of ipsilateral lung volume exceeding 30 Gy (V(30)ipsi), and planning target volume. These parameters divided the patients into low- and high-risk groups: if V(20)ipsi was 52% or lower, the risk of pneumonitis was 9%, and if V(20)ipsi was greater than 52%, the risk of pneumonitis was 46%; if V(30)ipsi was 39% or lower, the risk of pneumonitis was 8%, and if V(30)ipsi was greater than 39%, the risk of pneumonitis was 38%. Actuarial curves of the development of pneumonitis of Grade 2 or higher stratified by V(20)ipsi and V(30)ipsi were created. The correlation between pneumonitis and dosimetric constraints has been validated. Adding V(20)ipsi and V(30)ipsi to the classical total lung constraints could reduce pulmonary toxicity in concurrent chemoradiation treatment. V(20)ipsi and V(30)ipsi are important if the V(20) to the total lung, V(30) to the total lung, and mean lung dose have not exceeded the constraints of 31%, 18%, and 20 Gy, respectively.

Automated Algorithm for Quantifying the Extent of Cystic Change on Volumetric Chest CT: Initial Results in Lymphangioleiomyomatosis

The purpose of our study was to develop a new method for quantifying the severity of cystic lung disease using chest CT and to evaluate this method in patients with lymphangioleiomyomatosis (LAM). Eighteen patients with LAM (all women; mean age, 43.6 years) underwent chest CT and pulmonary function testing including diffusing capacity for carbon monoxide (DLCO). All patients were at their clinical baseline on the day of imaging. Standard quantitative CT metrics including the percentage of the lung volume < -910 HU and the 15th percentile of Hounsfield units were computed from the histogram of lung voxels. A new histogram analysis method was developed to compute the cyst volume and the volume of the remaining lung by segmenting the entire lung attenuation histogram into two underlying distributions, one from the cysts and the other from the remaining lung tissue. The mean +/- SD for quantitative lung metrics was 21% +/- 16% for percentage < -910 HU, -915 +/- 47 HU for 15th percentile of Hounsfield units, and 19% +/- 13% for cyst volume. The correlation between pulmonary function tests and CT metrics was strongest for the percentage of cyst volume for all pulmonary function testing indexes, with correlations between forced expiratory volume in 1 second (FEV(1)) percentage predicted and the CT metrics of r = -0.52, r = 0.50, and r = -0.86 for the percentage of lung < -910 HU, the 15th percentile of Hounsfield units, and the percentage of cyst volume, respectively. A new method for quantifying cyst volume as a percentage of total lung volume using chest CT correlates with pulmonary function parameters in patients with LAM and may have utility in the assessment of disease severity and progression of cystic lung diseases.

Image reconstruction affects computer tomographic assessment of lung hyperinflation

Lung hyperinflation may be assessed by computed tomography (CT). As shown for patients with emphysema, however, CT image reconstruction affects quantification of hyperinflation. We studied the impact of reconstruction parameters on hyperinflation measurements in mechanically ventilated (MV) patients. Observational analysis. A University hospital-affiliated research Unit. The patients were MV patients with injured (n = 5) or normal lungs (n = 6), and spontaneously breathing patients (n = 5). None. Eight image series involving 3, 5, 7, and 10 mm slices and standard and sharp filters were reconstructed from identical CT raw data. Hyperinflated (V(hyper)), normally (V(normal)), poorly (V(poor)), and nonaerated (V(non)) volumes were calculated by densitometry as percentage of total lung volume (V(total)). V(hyper) obtained with the sharp filter systematically exceeded that with the standard filter showing a median (interquartile range) increment of 138 (62-272) ml corresponding to approximately 4% of V(total). In contrast, sharp filtering minimally affected the other subvolumes (V(normal), V(poor), V(non), and V(total)). Decreasing slice thickness also increased V(hyper) significantly. When changing from 10 to 3 mm thickness, V(hyper) increased by a median value of 107 (49-252) ml in parallel with a small and inconsistent increment in V(non) of 12 (7-16) ml. Reconstruction parameters significantly affect quantitative CT assessment of V(hyper) in MV patients. Our observations suggest that sharp filters are inappropriate for this purpose. Thin slices combined with standard filters and more appropriate thresholds (e.g., -950 HU in normal lungs) might improve the detection of V(hyper). Different studies on V(hyper) can only be compared if identical reconstruction parameters were used.

Incidence of radiation pneumonitis after thoracic irradiation: Dose-volume correlates

To define clinical and dosimetric parameters correlated with the risk of clinically relevant radiation pneumonitis (RP) after thoracic radiotherapy. Records of consecutive patients treated with definitive thoracic radiotherapy were retrospectively reviewed for the incidence of RP of Grade 2 or greater by the Common Toxicity Criteria. Dose-volume histograms using total lung volume (TL) and TL minus gross tumor volume (TL-G) were created with and without heterogeneity corrections. Mean lung dose (MLD), effective lung volume (V(eff)), and percentage of TL or TL-G receiving greater than or equal to 10, 13, 15, 20, and 30 Gy (V10-V30, respectively) were analyzed by logistic regression. Receiver operating characteristic (ROC) curves were generated to estimate RP predictive values. Twelve cases of RP were identified in 92 eligible patients. Mean lung dose, V10, V13, V15, V20, and V(eff) were significantly correlated to RP. Combinations of MLD, V(eff), V20, and V30 lost significance using TL-G and heterogeneity corrections. Receiver operating characteristic analysis determined V10 and V13 as the best predictors of RP risk, with a decrease in predictive value above those volumes. Intrathoracic radiotherapy should be planned with caution when using radiotherapy techniques delivering doses of 10 to 15 Gy to large lung volumes.

1040: Hypofractionated Stereotactic Body Radiation Therapy for Lung Metastases

The curative treatment of oligometastases with radiotherapy remains an area of active investigation. The treatment of lung metastases with hypofrationated stereotactic body radiation therapy (SBRT) offers the potential for prolonging life with a low anticipated risk of toxicity. In patients with multiple (>5) metastases, SBRT of select lung lesions can also be used for aggressive palliation. Our single institution IRB-approved trials in patients with lung metastases explored the hypothesis that treating oligometastases with SBRT can prolong life and potentially cure patients, while in patients with multiple lung metastases SBRT can improve quality of life. To determine local control and toxicity after respiratory-gated stereotactic hypofractionated radiation as an adjunct to standard therapy for pulmonary metastasis. 50 patients with one or more metastases to the lung were treated on protocols U8700 and U9700 between February 2001 and December 2005. Individuals with 5 or fewer total lesions were treated with curative intent. Individuals with >5 metastases were treated to sites judged to impact respiratory function. One patient was lost to follow-up. 31 were treated curatively (30 evaluable) and 19 palliatively. Most patients (31/50) received 5 Gy per fraction for a total of 50 Gy in a median time of 2 weeks. Patient were 37 to 86 years old (median 60) and the number of targets treated per patient ranged from 1 to 5 (mean 2.6). Tumor sizes ranged from 0.3-7.7 cm in maximal diameter (0.1-125 ml; medians 2.1 cm, 4.7 ml). Dose-volume histograms were used to calculate the percentage of total lung volume (excluding the GTV) receiving ≥10 Gy (V10) and ≥20 Gy (V20). Mean follow-up was 18.7 months (range 3.7-60.9 months.) Local control of treated lesions was obtained in 42 of 49 evaluable patients (82%). Of the 125 total lesions treated, 8 progressed after treatment (94% local control). The diameter of tumors that recurred ranged from 1.5 to 3.0 cm in diameter. Failures in other anatomic locations within the lung occurred in 12/30 (40%), and failures elsewhere in the body occurred in 10 of the 30 patients (33%) treated with curative intent. 7 of these 30 (23%) are disease free (median 33 months). Many patients had subsequent hypofractionated treatments for control of new lesions. Median time from diagnosis of metastastic disease to completion of radiation was 14.8 months (range 1-89 months). Median survival from time of treatment completion was 14.9 months. Actuarial disease free survival of women with breast cancer was 40% at 40 months (n=10). Toxicity commonly included radiographic but clinically asymptomatic pulmonary changes (17/49), 3 (6.1%) had grade 2 complaints, and one had grade 3 toxicity. The grade 3 toxicity was a non-malignant pleural effusion successfully managed with pleurocentesis and sclerosis. His V10/V20 was 4%/21%. Most grade 2 toxicity was cough which was self limited. The mean V20 of the entire cohort of patients was 13%, with a range of 1-34%. Hypofractionated stereotactic radiotherapy results in a high local tumor control rate with low toxicity. Median survival time and disease free survival both appear better than that achieved with standard care alone. Long-term disease-free survival can be seen in a subset of patients when all tumors are targeted.

Impact of computed tomography and 18F-deoxyglucose coincidence detection emission tomography image fusion for optimization of conformal radiotherapy in non–small-cell lung cancer

To report a retrospective study concerning the impact of fused 18F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and CT images on three-dimensional conformal radiotherapy planning for patients with non-small-cell lung cancer. A total of 101 patients consecutively treated for Stage I-III non-small-cell lung cancer were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images, and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define the target volume. 18F-fluoro-deoxy-D-glucose-PET identified previously undetected distant metastatic disease in 8 patients, making them ineligible for curative conformal radiotherapy (1 patient presented with some positive uptake corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because the fused PET-CT images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT-PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT-PET image fusion reduced the pulmonary GTV in 6 patients (3 patients with atelectasis) and the mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients owing to an increase in the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Of 81 patients receiving a total dose of > or = 60 Gy at the International Commission on Radiation Units and Measurements point, after CT-PET image fusion, the percentage of total lung volume receiving >20 Gy increased in 15 cases and decreased in 22. The percentage of total heart volume receiving >36 Gy increased in 8 patients and decreased in 14. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. Multivariate analysis showed that tumor with atelectasis was the single independent factor that resulted in a significant effect on the modification of the size of the GTV by FDG-PET: tumor with atelectasis (with vs. without atelectasis, p = 0.0001). The results of our study have confirmed that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of non-small-cell lung cancer. However, FDG images using dedicated PET scanners and respiration-gated acquisition protocols could improve the PET-CT image coregistration. Furthermore, the impact on treatment outcome remains to be demonstrated.

Tomographie par émission de positons et détection en coïncidence (TEDC) et recalage d'images de simulation virtuelle par tomodensitométrie. Impact sur la planification de la radiothérapie conformationnelle des cancers bronchiques non à petites cellules

To report a retrospective study concerning the impact of fused 18F-fluorodeoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on three-dimensional conformal radiation therapy (3D-CRT) planning for patients with non-small-cell lung cancer (NSCLC). One hundred and one patients consecutively treated for stages I-III NSCLC were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define target volume. FDG-PET identified previously undetected distant metastatic disease in 8 patients making them ineligible for curative CRT (one patient presented some positive uptakes corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because fused CT/PET images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT/PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT/PET image fusion reduced pulmonary GTV in 6 patients (3 patients with atelectasis) and mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients due to an increase of the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Among 81 patients receiving a total dose > or = 60 Gy at ICRU point, after CT/PET image fusion, the percentage of total lung volume receiving more than 20 Gy (VL20) increased in 15 cases and decreased in 22 cases. The percentage of total heart volume receiving more than 36 Gy increased in 8 patients and decreased in 14 patients. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. After multivariate analysis, one single independent factor made significant effect of FDG/PET on the modification of the size of the GTV: tumor with atelectasis (P = 0.0001). Conclusion. - Our study confirms that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of patients with NSCLC. FDG images using dedicated PET scanners with modern image fusion techniques and respiration-gated acquisition protocols could improve CT/PET image coregistration. However, prospective studies with histological correlation are necessary and the impact on treatment outcome remains to be demonstrated.

Impact of CT and 18F-deoxyglucose positron emission tomography image fusion for conformal radiotherapy in esophageal carcinoma

To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiotherapy planning for esophageal carcinoma patients. Thirty-four esophageal carcinoma patients were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. PET images were coregistered using five fiducial markers. Target delineation was initially performed on CT images, and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. (18)F-fluorodeoxy-D-glucose-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative conformal radiotherapy. The gross tumor volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and increased in 7 patients (21%). The GTV reduction was > or =25% in 4 patients owing to a reduction in the length of the esophageal tumor. The GTV increase was > or =25% with FDG-PET in 2 patients owing to the detection of occult mediastinal lymph node involvement in 1 patient and an increased length of the esophageal tumor in 1 patient. Modifications of the GTV affected the planning treatment volume in 18 patients. Modifications of the delineation of the GTV and displacement of the isocenter of the planning treatment volume by FDG-PET also affected the percentage of total lung volume receiving >20 Gy in 25 patients (74%), with a dose reduction in 12 patients and dose increase in 13. In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of esophageal carcinoma. The affect on treatment outcome remains to be demonstrated.

Tomographie par émission de positons et fusion d'images de simulation virtuelle par tomodensitométrie. Impact sur la planification de la radiothérapie conformationnelle des cancers de l'œsophage

To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiation therapy (CRT) planning for patients with esophageal carcinoma. Thirty-four patients with esophageal carcinoma were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. PET-images were coregistered using five fiducial markers. Target delineation was initially performed on CT images and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. FDG-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative CRT. The Gross Tumor Volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and was increased in 7 patients (20.5%). The GTV reduction was >or=25% in 4 patients due to reduction of the length of the esophageal tumor. The GTV increase was >or=25% with FDG-PET in 2 patients due to the detection of occult mediastinal lymph node involvement in one patient and an increased length of the esophageal tumor in the other patient. Modifications of the GTV affected the planning treatment volume (PTV) in 18 patients. Modifications of delineation of GTV and displacement of the isocenter of PTV by FDG-PET also affected the percentage of total lung volume receiving more than 20 Gy (VL20) in 25 patients (74%), with a dose reduction in 12 patients and a dose increase in 13 patients. In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of patients with esophageal carcinoma related to modifications of GTV. The impact on treatment outcome remains to be demonstrated.

Improvement of ‘dynamic analgesia’ does not decrease atelectasis after thoracotomy

There is still controversy concerning the beneficial aspects of 'dynamic analgesia' (i.e. pain while coughing or moving) on the reduction of postoperative atelectasis. In this study, we tested the hypothesis that thoracic epidural analgesia (TEA) prevents these abnormalities as opposed to multimodal analgesia with i.v. patient controlled analgesia (i.v. PCA) after thoracotomy. Fifty-four patients undergoing thoracotomy (lung cancer) were randomly assigned to one of the two groups. Clinical respiratory characteristics, arterial blood gas, and pulmonary function tests (forced vital capacity and forced expiratory volume in 1 s) were obtained before surgery and on the next 3 postoperative days. Atelectasis was compared between the two groups by performing computed tomography (CT) scan of the chest at day 3. Postoperative respiratory function and arterial blood gas values were reduced compared with preoperative values (mean (SD) FEV1 day 0: 1.1 (0.3) litre; 1.3 (0.4) litre) but there was no significant difference between groups at any time. PCA and TEA provided a good level of analgesia at rest (VAS day 0: 21 (15/100); 8 (9/100)), but TEA was more effective for analgesia during mobilization (VAS day 0: 52 (3/100); 25 (17/100)). CT scans revealed comparable amounts of atelectasis (expressed as a percentage of total lung volume) in the TEA (7.1 (2.8)%) and in the i.v. PCA group (6.71 (3.2)%). There was no statistical difference in the number of patients presenting with at least one atelectasis of various types (lamellar, plate, segmental, lobar).

ARDS after pulmonary contusion: accurate measurement of contusion volume identifies high-risk patients.

The pathophysiology of pulmonary contusion (PC) is poorly understood, and only minimal advances have been made in management of this entity over the past 20 years. Improvement in understanding of PC has been hindered by the fact that there has been no accurate way to quantitate the amount of pulmonary injury. With this project, we examine a method of accurately measuring degree of PC by quantifying contusion volume relative to pulmonary function and outcome. Patients with PC from isolated chest trauma who had admission chest computed tomographic scan were identified from the registry of a Level I trauma center over a 1.5-year period. Subsequently, prospective data on all patients admitted to the intensive care unit with PC during a 5-month period were collected and added to the retrospective database. Using computer-generated three-dimensional reconstruction from admission chest computed tomographic scan, contusion volume was measured and expressed as a percentage of total lung volume. Admission pulmonary function variables (Pao2/FiO2, static compliance), injury descriptors (chest Abbreviated Injury Score, Injury Severity Score, injury distribution), and indicators of degree of shock (admission systolic blood pressure, admission base deficit) were documented. Outcomes included maximum positive end-expiratory pressure, ventilator days, pneumonia, and acute respiratory distress syndrome (ARDS). Forty-nine patients with PC (35 bilateral) were identified. The average severity of contusion was 18% (range, 5-55%). Patients were classified using contusion volume as severe PC (> or =20%, n = 17) and moderate PC (< 20%, n = 32). Injury Severity Score was similar in the severe and moderate groups (23.3 vs. 26.5, p = 0.33), as were admission Glasgow Coma Scale score (12 vs. 13, p = 0.30), admission blood pressure (131 vs. 129 mm Hg, p = 0.90), and admission Pao2/Fio2 (197 vs. 255, p = 0.14). However, there was a much higher rate of ARDS in the severe group as compared with the moderate group (82% vs. 22%, p < 0.001). There was a trend toward higher pneumonia rate in the severe group, with 50% of patients in the severe group developing pneumonia as compared with 28% in the moderate group (p = 0.20). Extent of contusion volumes measured using three-dimensional reconstruction allows identification of patients at high risk of pulmonary dysfunction as characterized by development of ARDS. This method of measurement may provide a useful tool for the further study of PC as well as for the identification of patients at high risk of complications at whom future advances in therapy may be directed.

Impact of setup variability on incidental lung irradiation during tangential breast treatment

This study aimed to determine the variability in treatment setup during a 5-week course of tangential breast treatment for patients immobilized in a customized hemibody cradle, to assess the relationship between the height of the lung shadow on the tangential port film and the percentage of lung volume irradiated, and to estimate the impact of setup variabilities on irradiated lung volume. One hundred seventy-two port films were reviewed from 20 patients who received tangential beam treatment for breast cancer. The height of the lung shadow at the central axis (CLD) on each port film was compared to the corresponding simulator film as an assessment of setup variability. A three-dimensional dose calculation was performed, and the percentage of total lung volume within the field was correlated with the CLD. The three-dimensional dose calculation was repeated for selected patients with the location of the treatment beams modified to reflect typical setup variations. The CLD measured on the port films was within 3 mm of that prescribed on the simulator film in 43% (74 of 172) of the port films. The variation was 3-5 mm in 26%, 5-10 mm in 25%, and >10 mm in 6%. The height of the lung shadow correlated with the percentage of lung volume included in the radiation field (r2 = 0.6). Typical variations in treatment setup resulted in < or = 5% fluctuation in the absolute volume of ipsilateral lung irradiated. The current immobilization system used in our clinic provides a clinically acceptable reproducibility of patient setup. The height of the lung shadow is reasonably well correlated with the percentage of irradiated lung volume. During a typical 5-week course of radiotherapy, the ipsilateral irradiated lung volume fluctuates <5%.

Pulmonary function measurements

1. 1. An accurate evaluation of the degree of pulmonary function impairment may be made from the following physiologic tests: (1) ventilation measurements from spirogram tracings (total vital capacity, three-second vital capacity, maximal breathing capacity and the shape of the exhalation curve following a deep breath); (2) the degree of bronchospasm present; (3) the residual volume and alveolar nitrogen percentage after seven minutes of oxygen breathing; (4) the arterial blood-oxygen saturation at rest and immediately after step-up exercise; (5) the oxygen uptake during step-up exercise; (6) the percentage of oxygen extracted from the inspired air breathed; and (7) the character and duration of dyspnea after step-up exercise. 2. 2. A numerical ventilation factor derived from the three-second vital capacity (a timed measurement), the maximal breathing capacity and the residual percentage of total lung volume, the three most important aspects related to breathing resistance and pulmonary ventilation, has been found to be a useful measurement in pulmonary function evaluation. 3. 3. The great importance of comparing resting and exercise measurements in pulmonary function studies, and especially arterial blood-oxygen saturation, is stressed. 4. 4. Intermittent positive pressure breathing has been found a helpful treatment procedure for oxygen administration in hypercapnia and for giving some relief from the dyspnea of chronic pulmonary insufficiency. The more effective treatment of the bronchospasm, the improved bronchial drainage and the deep-breathing exercise constitute the more important aspects in decreasing breathing resistance and, in turn, the dyspnea.

THE LUNG VOLUME IN HEART DISEASE

The lung volumes in a group of individuals suffering from chronic cardiac disease have been studied by a method which is applicable to patients suffering from dyspnea. In a number of instances the same patients were investigated during various stages of decompensation and compensation. The values found have been compared with those determined in a group of normal subjects. Lung volumes have been considered from three points of view: (1) relative lung volumes or subdivisions of total lung volume expressed as percentage of total lung volume; (2) the absolute lung volumes of patients with heart disease have been compared with lung volumes calculated for normal individuals having similar surface areas or chest measurements; and (3) in individual cases absolute lung volumes have been measured in various stages of compensation and decompensation. (1) In patients with heart disease it has been observed that the vital capacity forms a portion of the total lung volume relatively smaller than in normal individuals, and that the mid-capacity and residual air form relatively larger portions. When the patient progresses from the compensated to the decompensated state these changes become more pronounced. (2) When the absolute lung volumes determined for patients are compared with volumes of the same sort, as calculated for normal individuals of the same surface areas and chest measurements, the following differences are found. The vital capacities are always smaller in the patients and the volumes of residual air are always larger. There is a tendency for middle capacity and total capacity to be smaller, though, when the patients are in a compensated state, these volumes may approximate normal. (3) When decompensation occurs the absolute lung volumes undergo changes as follows: (a) vital capacity, mid-capacity, and total capacity decrease in volume; and (b) the residual air may either increase or decrease according to the severity of the state of decompensation. The significance of these changes has been discussed and an explanation offered for the occurrence of a residual air of normal volume in patients with heart disease. It results from a combination of two tendencies working in opposite directions: one to increase the residual air-stiffness of the lungs (Lungenstarre); the other to decrease it-distended capillaries (Lungenschwellung), edema, round cell infiltration.