Inhalation Scans Research Articles

Computer-assisted evaluation of small airway disease in CT scans of Iran-Iraq war victims of chemical warfare by a locally developed software: comparison between different quantitative methods

ObjectiveDiagnosis of small airway disease on computed tomography (CT) scans is challenging in patients with a history of chemical warfare exposure. We developed a software package based on different methodologies to identify and quantify small airway disease in CT images. The primary aim was to identify the best automatic methodology for detecting small airway disease in CT scans of Iran-Iraq War victims of chemical warfare.MethodsThis retrospective case–control study enrolled 46 patients with a history of chemical warfare exposure and 27 controls with inspiratory/expiratory (I/E) CT scans and spirometry tests. Image data were automatically segmented, and inspiratory images were registered into the expiratory images' frame using the locally developed software. Parametric response mapping (PRM) and air trapping index (ATI) mapping were performed on the CT images. Conventional QCT methods, including expiratory/inspiratory mean lung attenuation (E/I MLA) ratio, normal density E/I (ND E/I) MLA ratio, attenuation volume Index (AVI), %low attenuation areas (LAA) < -856 in exhale scans, and %LAA < -950 in inhale scans were also computed. QCT measurements were correlated with spirometry results and compared across the two study groups.ResultsThe correlation analysis showed a significant negative relationship between three air trapping (AT) measurements (PRM, ATI, and %LAAExp < -856) and spirometry parameters (Fev1, Fvc, Fev1/Fvc, and MMEF). Moreover, %LAAExp < -856 had the highest significant negative correlation with Fev1/Fvc (r = -0.643, P-value < 0.001). Three AT measurements demonstrated a significant difference between the study groups. The E/I ratio was also significantly different between the two groups (P-value < 0.001). Binary logistic regression models showed PRMFsad, %LAAExp < -856, and ATI as significant and strong predictors of the study outcome. Optimal cut-points for PRMFsad = 19%, %LAAExp < -856 = 23%, and ATI = 27% were identified to classify the participants into two groups with high accuracy.ConclusionQCT methods, including PRM, ATI, and %LAAExp < -856 can greatly advance the identification and quantification of SAD in chemical warfare victims. The results should be verified in well-designed prospective studies involving a large population.

SU‐E‐J‐25: Analysis of Commercial 4DCT Flaws and the Potential Benefits of a New Technique for Irregular Breathing Patients

Purpose:To determine the distribution of inhalation to exhalation breathing amplitudes as measured using a commercial 4DCT and a proposed 4DCT protocol for irregular breathing patients.Methods:External breathing surrogate signals correlating with lung tidal volume were collected using an abdominal bellows for a set of 50 patients. Breathing traces over 5‐minute durations were evaluated and the peak inhalation and exhalation peaks identified. An arbitrary time point was identified and the nearest exhalation peak located within a ±180° gantry rotation period. The times at which the follow‐up inhalation scans occurred were correlated with the couch velocity to determine whether the tumor would be within 180° of that specific peak inhalation given the CT scanner coverage, pitch, rotation period, tumor size, and tumor motion amplitude (defined in units of centimeters per bellows signal). The imaged tumor motion amplitude was based on which inhalation peak would be imaged and the couch location at that time relative to the exhalation peak. This analysis provided a series of measured breathing motion amplitudes, which were compared against the 85th percentile motion, consistent with the proposed 4DCT protocol. Because the 4DCT scans would yield a single amplitude determination for each patient, errors in the amplitude measurement were considered systematic. Therefore, the largest 5% and smallest 5% of the measured amplitudes were selected to identify over‐and under‐determined motion amplitudes.Results:30% of the patients exhibited breathing amplitude overestimations of at least 27%, while 30% showed underestimations of at least 34%.Conclusion:For the majority of patients, the current system provided a high probability of correct breathing motion amplitude measurements. 30% had a significant chance of a systematic over‐ or under‐estimation of tumor motion. The proposed protocol will be immune to such irregularities because the entire breathing trace is used for breathing motion amplitude assessments.

Comparison of Radiotherapy Treatment Plans for Left-sided Breast Cancer Patients based on Three- and Four-dimensional Computed Tomography Imaging

Aims The target volume for breast radiotherapy after conservative surgery for breast cancer may be affected by breathing motion. We investigated differences between conventional and four-dimensional computed tomography-based treatment planning and whether gating could improve dose volume parameters. Materials and methods Ten patients with left-sided breast cancer and surgical clips at the excision site had conventional treatment planning computed tomography and four-dimensional computed tomography. Treatment plans using two tangential beams (6 MV X-rays) were optimised for target coverage and homogeneity using a field in field technique for the three-dimensional scan. This plan was applied directly to four-dimensional datasets representing individual phases of the breathing cycle and combinations thereof (average and maximum intensity projection). Optimised plans were generated for the maximum inhalation scan to study what could potentially be achieved in gated radiotherapy. Results Four-dimensional computed tomography with effective doses of around 10 mSv proved to be adequate for treatment planning in all patients. The average motion of the surgical clips was 3.7 mm (range 1.7–6.5 mm), which was similar to the movement of the chest wall. With a margin of 7 mm for the whole breast to planning target volume, conventional three-dimensional computed tomography-based planning was found to adequately cover the target as seen on four-dimensional computed tomography without significant differences in normal tissue sparing. Improved sparing of the heart and lung could only be achieved by reducing the posterior margin of the target volume, which may be justified if four-dimensional computed tomography is used to determine the target and its motion. Conclusion No significant benefit has been shown for the use of four-dimensional computed tomography-based planning if motion management is not implemented concurrently with a reduced posterior margin between clinical and planning target volumes.

Interfraction and Respiratory Organ Motion During Conformal Radiotherapy in Gastric Cancer

To quantify the interfraction and breathing organ motion during adjuvant radiotherapy for gastric cancer and assess organ stability in different breathing states. A planning computed tomography (CT) scan and serial study CT scans in free breathing, voluntary inhale and exhale were performed in weeks 1, 3, and 5 of radiotherapy for 22 resected gastric patients. All data sets were fused to register the vertebral bodies. The regions of interest (kidneys, stomach, liver, pancreas, celiac axis, and porta hepatis) or points of interest (POIs; left dome of diaphragm, splenic hilum) were identified. For each region of interest, a POI was automatically placed at the center of mass. The interfraction displacement and breathing amplitude were assessed in the craniocaudal (CC), anteroposterior (AP), and right-left (RL) directions. Comparison of the serial free-breathing CT scans with the planning CT scan showed a median displacement of all POIs of 5.6, 2.2, and 1.8 mm in the CC, AP, and RL directions, respectively. Comparison of the serial inhale scans with the first inhale scan showed a displacement of 4.9, 2.6, and 1.8 mm in the CC, AP, and RL directions, respectively. The comparable values for the exhale scans were 5.1, 2.0, and 1.8 mm. The displacements of the organs were similar in the free breathing, inhale, and exhale states. The median respiratory amplitude in the CC, AP, and RL direction was 14, 4.8, and 1.7 mm, respectively. The median interfraction displacement of the POIs relative to the vertebral bodies was about 6 mm in the CC direction and 2 mm in the other directions. The planning target volume margins need to account for these shifts. Individual assessment of respiratory motion is recommended to identify patients with unusually large respiratory amplitude.

The Efficacy of Enoxaparin for the Prevention of a Pulmonary Thromboembolism in a Skin-sparing Mastectomy with Immediate Reconstruction in Breast Cancer

immediate reconstruction provides psychological satisfaction and good cosmetic outcome for patients with breast cancer. However, this is a lengthy procedure to perform, and there is increased risk of pulmonary thromboembolism (PTE). The purpose of this study was to evaluate the efficiency of the use of low molecular weight heparins (enoxaparin) for prophylaxis against a pulmomary thromboembolism followed by mastectomy with an immediate transverse rectus abdominis myocutaneous flap (TRAM) in breast cancer. Methods: A total of 123 patients underwent a skin-sparing mastectomy with an immediate TRAM. The ‘‘non-enoxaparin group’’ wore compression stockings for PTE prophylaxis and the ‘‘enoxaparin group’’ received enoxaparin (40 mg SC injection, once daily starting 2 hr before surgery and continuing for 6 days postoperatively) in conjunction with the use of compression stockings. Lung perfusion, inhalation scans, and serum D-dimer assays were performed on postoperative day 3. If findings were clinically suspicious or intermediate to high probability of a PTE in a lungs scan, embolism computed tomography was performed. Patients were prospectively investigated according to the clinicopathological data. We compared the incidence of PTE and hemorrhagic complications between the two groups. Results: There were no significant clinicopathological differences between the two groups. Eleven patients developed a PTE (nine patients in the non-enoxaparin group and two patients in the enoxaparin group). The prevalence rate of a PTE was 17.3% and 3.2% for each group, respectively (p= 0.01). One patient in the non-enoxaparin group required a second operation for bleeding control and three patients in the enoxaparin group needed transfusions. There were minor hemorrhagic complications in the enoxaparin group that improved after supportive management. Conclusion: Although there were minor hemorrhagic complications, enoxaparin is safe and effective in a preventing PTE in patients that undergo immediate reconstruction after a skin-sparing mastectomy.

SU‐FF‐J‐65: Feasibility Study of Management of Respiration Induced Target Motion for the Radiotherapy Treatment of Lung Cancer Patients in the Absence of a 4DCT Simulator

Purpose: Varian's RPM™ system for respiration induced tumor motion management allows acquisition of CT images and gated treatments under free breathing. 4DCT may not be possible because of lack availability of appropriate CT hardware or software. This study evaluated whether a breath hold CT scanning technique can be used as a substitute for a 4DCT scan. Materials and Methods: A 4DCT scan is obtained on a 4 slice GE Lightspeed™ scanner with the patient breathing freely and the respiratory period regulated using audiovisual cues from RPM™. Additional helical scans are obtained using an end inhalation or exhalation breath hold modified gating method (MGM). The PTV is drawn on the MGM scan(s) and for each of phase of the 4DCT scan. Comparison of target volume, centroid and extent of target volume is made between the MGM scan and the corresponding phase of the 4DCT scan. A treatment plan is developed using the MGM scan. Dose is recalculated using the 4DCT scan with the beam's isocenter and apertures obtained from the MGM scan. DVH comparison is made. Results: 20 patients had both a 4DCT scan and at least one MGM scan. 8 patients exhibited respiration induced target motion of &gt;5 mm during free breathing. Maximum target motion observed was 25 mm. For 14 end inhalation scans, 9 passed, 3 passed marginally, and 2 failed the equivalency tests to the corresponding 4DCT scan. For 18 end exhalation scans, 14 passed, 4 passed marginally, and 0 failed the equivalency tests to the corresponding 4DCT scan. Conclusion: All end exhalation breath hold scans are suitable substitutes for the corresponding phase 50 4DCT scan. However only 6/18 patients exhibited sufficient (&gt;5 mm) respiration induced target motion on which to base any conclusions about the suitability of MGM. Conflict of Interest: Research supported by Varian Medical Systems.

Positron Emission Tomography Imaging of Regional Pulmonary Perfusion and Ventilation

Positron emission tomography (PET) imaging is a noninvasive, quantitative method to assess pulmonary perfusion and ventilation in vivo. The core of this article focuses on the use of [13N]nitrogen (13N2) and PET to assess regional gas exchange. Regional perfusion and shunt can be measured with the 13N2-saline bolus infusion technique. A bolus of 13N2, dissolved in saline solution, is injected intravenously at the start of a brief apnea, while the tracer kinetics in the lung is measured by a sequence of PET frames. Because of its low solubility in blood, virtually all 13N2 delivered to aerated lung regions diffuses into the alveolar airspace, where it accumulates in proportion to regional perfusion during the apnea. In contrast, lung regions that are perfused but are not aerated and do not exchange gas (i.e., "shunting" units) do not retain 13N2 during apnea and the tracer concentration drops after the initial peak. Accurate estimates of regional perfusion and regional shunt can be derived by applying a mathematical model to the pulmonary kinetics of a 13N2-saline bolus. When breathing is resumed, specific alveolar ventilation can be calculated from the tracer washout rate, because 13N2 is eliminated almost exclusively by ventilation. Because of the rapid elimination of the tracer, 13N2 infusion scans can be followed by 13N2 inhalation scans that allow determination of regional gas fraction. This article describes insights into the pathophysiology of acute lung injury, pulmonary embolism, and asthma that have been gained by PET imaging of regional gas exchange.

Bronchiolitis obliterans after bone marrow transplantation: evaluation with lung scintigraphy.

Bronchiolitis obliterans (BO) has been described as a main pulmonary complication following allogeneic bone marrow transplantation (BMT). Diagnosis of BO is usually based on clinical findings, pulmonary function tests, and computed tomography scan. However, histological examination of an open-lung biopsy specimen may sometimes be necessary to confirm the diagnosis, despite its relative invasiveness. The ventilation lung scan is another useful but non-invasive diagnostic method. In this study, we present two post-transplant BO cases, each showing different clinical conditions, characterized by delayed wash-out on 133Xe gas and airway depositions on radioaerosol inhalation scans. These methods succeeded in revealing pulmonary obstruction in cases where the pulmonary function tests were within normal range and the high-resolution CT scans (HR-CT) of the chest were only minimally abnormal, suggesting their usefulness as an additional tool in the diagnosis of post-transplant BO, as well as in the follow-up to pulmonary obstruction.

Clinical studies of alveolar-capillary permeability using technetium-99m DTPA aerosol.

Soluble radioaerosols such as technetium-99m diethylene triamine pentacetate (DTPA) permit simple quantitative studies of alveolar-capillary permeability to be performed, since the submicronic aerosols are deposited mainly at the lung periphery and are cleared across the alveolar-capillary membrane. Regional alterations in permeability can also be noted using this radionuclide technique. We have measured the pulmonary epithelial permeability in normal subjects and the alteration in smokers, in glue-sniffers, in patients with inhalation burns, in chronic obstructive pulmonary disease (COPD) and in patients with lung metastases from thyroid cancer treated with radioiodine131I. In the normal volunteers, the time taken for 50% of inhaled99mTc DTPA to be cleared from the lungs (T1/2) was 66 minutes ± lsd of 12 mins. The smokers had a mean T1/2 of 20 mins ± lsd 4 min. In the hard-core glue-sniffing group, the majority were smokers who had stopped smoking and gluesniffing for periods varying from 1 day to 42 days, and it was possible to note the changes in clearance times against period of abstinence.In the patients with inhalation burns, there was change in lung clearance arising from pulmonary epithelial damage; these patients showed increased rate of clearance (short T1/2) with mean T1/2 of 36 min ± 1 sd of 11 mins, while the retention images revealed regional lung damage in moderately severe inhalation burns. Twenty-four patients with COPD had inhalation scans done with Tc-99m tin colloid radioaerosol, and these images were compared with the perfusion lung scans done with99mTc macroaggregated albumin (MAA); in general the perfusion images matched the defects noted in the inhalation scans. The99mTc DTPA clearance rate in these patients was normal i.e. T1/2 = 78 ± 14 mins. In the thyroid cancer patients with lung metastases, who had high doses of radioiodine treatment, the T1/2 values were normal or prolonged slightly, mean T1/2 = 76 min ± 23.

Comparison of Inhalation Scan and Perfusion Scan for the Prediction of Postoperative Pulmonary Function

Background Because of the common etiologic factor, such as smoking, lung cancer and chronic obstructive Pulmonary disease are often present in the same patient. The preoperative prediction of remaining pulmonary function after the resectional surgery is very important to prevent serious complication and postoperative respiratory failure. 99mTc-MAA perfusion scan has been used for the prediction of postoperative pulmonary function, but it may be inaccurate in case of large V/Q mismatching. We compared 99mTc-DTPA radioaerosol inhalation scan with 99mTc-MAA perfusion scan in predicting postoperative lung function. Method Preoperative inhalation scan and/or perfusion scan were performed and pulmonary function test were performed preoperatively and 2 month after operation. We predicted the postoperative pulmonary functions using the following equations. Postpneumonectomy FEV1=Preop FEV1x% of total function of lung to remain Results 1) The inhalation scan showed good correlations between measured and predicted FEV1, FVC and FEF25-75%. (correlation coefficiency; 0.94, 0.91, 0.87 respectively). 2) The perfusion scan also showed good correlations between measured and predicted FEV1, FVC and FEF25-75%. (correlation coefficiency; 0.86, 0.72, 0.97 respectively). 3) Among three parameters, FEV1 showed the best correlations in the prediction by lung scans. 4) Comparison between inhalation scan and perfusion scan in predicting pulmonary function did not show any significant differneces except FVC. Conclusion The inhalation scan and perfusion scan are very useful in the prediction of postoperative lung function and don't make a difference in the prediction of pulmonary function although the former showed a better correlation in FVC.

Frequency of pulmonary embolism in ambulant patients with pelvic vein thrombosis: A prospective study

One hundred thirty-nine consecutive patients (average age 70.1 years) who were able to walk with a swollen leg were seen at the clinic where diagnosis of acute deep vein thrombosis (DVT) extending to the pelvis was confirmed by injecting microspheres labeled with technetium 99m into the dorsal foot vein (radionuclide venography). Thirty-nine (28%) of these patients had malignant disease. Perfusion lung scans performed immediately after radionuclide venography were supplemented by inhalation scans (99mTc-labeled diethylenetriamine pentaacetic acid aerosol) in case of perfusion defects. During scintigraphy patterns highly indicative of pulmonary embolism (PE) were found in 80 patients (58%), but only 11 (7.9%) had minor clinical symptoms. All patients were admitted to the ward, were given standard heparin subcutaneously (35,000 to 40,000 units/24 hr) and firm bandages, and were encouraged to walk. After 11 days pulmonary scintigraphy was repeated and revealed no change in 55 of 59 patients without PE and in 40 of 80 patients with PE. Thirty-three patients (23.7%) showed regression of perfusion defects. New PE developed in 11 patients (7.9%, four without and seven with previous PE). Autopsy revealed that one 80-year-old patient with prostatic carcinoma had died of massive PE. When comparing this frequency of newly developed PE during ambulation with the occurrence of PE after bed rest, according to the literature, it is no more dangerous for a mobile patient with proximal DVT to walk wearing a firm bandage than it is for the patient to be in bed. Therefore we recommend treating mobile patients with DVT by use of anticoagulation and firm compression bandages and without immobilization.

Functional assessment of canine lung transplants by radioisotope lung scanning procedures.

Thirty-four dogs with left lung allografts, 21 of which were fresh and 13 preserved, and 14 dogs with autografts were studied sequentially by radioisotope inhalation and perfusion lung scanning procedures. Allografts and autografts were found to function well immediately after operation. In autografts, both ventilation and perfusion were well maintained during the period of study. In allografts, ventilation deteriorated sooner and more markedly than perfusion. The ventilation-perfusion index decreased more rapidly and to a greater degree in the preserved transplants than in the fresh allografts. Partial bronchial obstruction at the bronchial anastomotic site was indicated on the aerosol inhalation scan as an area of excessive radioactive deposition. Such findings occurred transiently in allografts and autografts in the immediate postoperative period as a result of edema, at the time of rejection (7 to 30 days) in allografts, and many months postoperatively in autografts as a result of bronchostenosis by s...

A Dual Lung-Scanning Technic for Evaluation of Pulmonary Function

The recent development of lung scanning with 5–50 μ, size aggregates of human serum albumin I31 has demonstrated the feasibility of scanning methods in evaluating pulmonary function (1–4). Injected intravenously, these particles are trapped temporarily in the pulmonary arteriolar-capillary bed with high efficiency on the first pass, and the subsequent scan image gives a semiquantitative estimate of pulmonary arterial blood flow distribution (5–7). Conceivably, information concerning airway patency could be obtained by scanning after inhalation of radioaerosols if a sufficient fraction were deposited uniformly throughout the lower respiratory tract and retained for a few hours. This preliminary report describes an inhalation technic which, combined with the intravenous method, provides a dual scanning procedure for the evaluation of regional pulmonary arterial blood flow and bronchial patency. Method Animal Studies: Mongrel dogs weighing from 7 to 19 kg are anesthetized with pentobarbital and intubated with a cuffed endotracheal tube. This tube is attached to a positive pressure respirator2 equipped with a nebulizer and exhalation manifold. The exhaust line is passed through a filter, and the inhalation procedure is carried out in a vented hood. Three to 4 ml of radioactive solution containing approximately 1 millicurie of isotope, 10 per cent glycerin, and 0.2 per cent tyloxypal3 are nebulized in a thirty-to-sixty-minute period. The animals are then scanned in the prone position. Normal animals in various positions and others with pulmonary arterial obstructions, complete and partial bronchial obstructions, and phrenic nerve section have been studied. Human Studies: Six normal subjects and 27 patients with various lung disorders have had inhalation scans. A commercial respirator-nebulizer with a mouthpiece and exhalation manifold is used. 4 The exhaust line runs to a filter in a vented hood. Three to 4 ml of the same radioactive solutions used for animals are nebulized and inhaled in ten to twenty minutes and the patient is scanned in the prone position. Immediately following this procedure, or the next day, the intravenous preparation is given and the scan is repeated. Results Numerous physiologic test materials labeled with Au 198 I131, I125, Hg197, or Tc99m were tested in dogs. Satisfactory inhalation scans are produced with aerosols of I131, I125 and Tc99m-Iabeled human serum albumin, Hg197 chlormerodrin and colloidal Au 198. The low energy I125, Hg197, and Tc99m labels are desirable because subsequent intravenous scanning with higher energy I131-albumin macroaggregates can be performed immediately with a scanner equipped with pulse-height discrimination.5 Sixty-two combined scan procedures were performed in 24 animals. Intravenous and inhalation scans in the prone or supine position have a similar appearance. After inhalation, little radioactivity is detectable in the trachea or major bronchi.