Perfusion Lung Scan Research Articles

Lung Perfusion Scan for Pulmonary Embolism and Shunt Detection: An Effective Diagnostic Tool

Pulmonary embolism (PE) can lead to chronic thromboembolic pulmonary hypertension (CTEPH) which can resultin right heart failure. Therefore, timely management of this condition can save patients from serious complications.In the department of Nuclear Medicine, ventilation perfusion (V/Q) scan has been used to supplement detection ofPE especially in cases where contrast based computed tomography pulmonary angiography (CTPA) cannot beperformed. With the advent of single photon emission computed tomography (SPECT/CT), perfusion scan withSPECT/CT is being frequently used. It has also been used for the diagnosis of various other indications such as rightto left cardiac shunts in addition to PE. Technetium 99m macroaggregated human serum albumin (99mTc HSA) iscommonly used in lung perfusion scans. It can also be taken up by extra pulmonary organs such as brain or kidneysdue to presence of shunt. We present an interesting case of simultaneous detection of PE and right to left shunt ina young patient.Keywords: Pulmonary embolism, ventilation perfusion scan, right to left shunt, brain uptake.

Preoperative Multivariable Model for Risk Stratification of Hypoxemia During One-Lung Ventilation.

Hypoxemia occurs with relative frequency during one-lung ventilation (OLV) despite advances in airway management. Lung perfusion scans are thought to be one of the most accurate methods to predict hypoxemia during OLV, but their complexity and costs are well-known limitations. There is a lack of preoperative stratification models to estimate the risk of intraoperative hypoxemia among patients undergoing thoracic surgery. Our primary objective was to develop a risk stratification model for hypoxemia during OLV based on preoperative clinical variables. This is a single-center, retrospective cohort study including 3228 patients who underwent lung resections with OLV from 2017 to 2022, at a tertiary academic health care center in the United States. Vital signs and ventilator settings were retrieved minute by minute. Intraoperative hypoxemia was defined as an episode of oxygen desaturation (Spo2 <90%) for at least 5 minutes. Demographic and clinical characteristics were included in a stepwise logistic regression, which was used for the selection of predictors of the risk score model. All patients included in this cohort underwent elective lung surgery in lateral decubitus position, with double lumen tube and placement confirmation with fiberoptic bronchoscopy. Our model was validated internally using area under the receiver operating curves (AUC) with bootstrapping correction. The incidence of hypoxemia during OLV was 8.9% (95% confidence interval [CI], 8.0-10.0). Multivariable logistic regression identified 9 risk factors with their corresponding scoring: preoperative Spo2 <92% (15 points), hemoglobin <10 g/dL (6 points), age >60 years old (4 points), male sex (4 points), body mass index >30 kg/m2 (8 points), diabetes mellitus (4 points), congestive heart failure (7 points), hypertension (3 points), and right-sided surgery (3 points). The AUC of the model after bootstrap correction was 0.708 (95% CI, 0.676-0.74). Based on the highest Youden index, the optimal score for predicting intraoperative hypoxemia was 13. The risk of hypoxemia increased from 4.7% in the first quartile of scores (0-13 points), to 32% in the third quartile (27-39 points), and 83.3% in the fourth quartile (>39 points). At scores of 20 or greater, the specificity of the model exceeded 90% and reached a positive predictive value of 80%. The risk of hypoxemia during OLV can be stratified preoperatively using accessible clinical variables. Our risk model is well calibrated but showed moderate discrimination for predicting intraoperative hypoxemia. The accuracy of preoperative models for risk stratification of hypoxemia during OLV should be explored in prospective studies.

Incidence of fatal and non-fatal pulmonary thromboembolism after removal of tunnelled central venous haemodialysis catheters without ultrasound scan and anticoagulation.

Catheter related thrombosis is a common complication of tunnelled central venous catheter (TCVC) usage. There are concerns that TCVC removal could dislodge a thrombus to cause pulmonary thromboembolism (PE). The incidence of PE following TCVC removal is unclear and so the aim of this study was to investigate the incidence of PE and whether it is high enough to warrant screening with ultrasound with a view to systemic anticoagulation prior to TCVC removal. 1102 consecutive TCVC removals without ultrasound and systemic anticoagulation were included in this retrospective study. Data were extracted from electronic health records. Measures to identify PE events included: deaths, computed tomography pulmonary angiogram (CT-PA), isotope lung perfusion scans and D-dimers blood tests within 7 days of removal. Of the 1102 TCVC removals, the mean age of patients was 56.9 years and 57.3% were male. The primary renal diagnosis for 24.5% of patients was diabetic nephropathy. There were seven deaths following removal, none of which had PE as a contributing cause on review of their clinical history and death certificates. Five CT-PAs and one isotope lung perfusion scan were carried out in the 7 days after TCVC removal and none had a positive finding of PE. Three patient had D-dimers measured in blood within 7 days and none of these patients were subsequently diagnosed with PE. There was no evidence of fatal or non-fatal PE's occurring in the 7 days following TCVC removal. This would support the practice of removing TCVCs without the need for ultrasound screening and without a period of systemic anticoagulation.

Impact of COVID-19 on Ventilation-Perfusion (V/Q) Scans: A Comparative Analysis of Pre-COVID-19 Era V/Q Scans and Post-COVID-19 Era Perfusion Scans.

Introduction The COVID-19 pandemic has profoundly impacted medical practices, including nuclear medicine. To minimize aerosol transmission risks, lung perfusion scintigraphy was preferred over traditional ventilation-perfusion (V/Q) scintigraphy during the pandemic. This study compares lung perfusion scans performed during COVID-19 with V/Q scans from the pre-COVID era. After reviewing this study, the reader will learn about V/Q scintigraphy and lung perfusion. Methods This retrospective observational study, conducted from December 2018 to July 2021, involved 868 patients - 511 in the pre-COVID era and 357 in the post-COVID era - at a single tertiary care center. The pretest probability of pulmonary embolism (PE) was determined using Wells' criteria, and data including demographics, clinical findings, and diagnostic test results (V/Q or lung perfusionscintigraphy) were collected. Results A 30% decline in lung scans was observed during the pandemic. In the pre-COVID era, 68.3% of scans had low, 27.8% had intermediate, and 3.9% had high probability for PE. During the pandemic, perfusion-only scans showed 57.3% low, 32.9% indeterminate, and 9.8% high probability for PE. Among COVID-19-positive patients, 48.9% had intermediate, and 11.1% had high probability scans. The rise in indeterminate and high-probability scans during the pandemic is attributed to COVID-19-related lung changes and hypercoagulability. Conclusion The perfusion component of lung scans is typically sufficient for evaluating acute PE. Omitting the ventilation part of the V/Q scan had minimal impact, with only a 5.1% increase in indeterminate/non-diagnostic scans using perfusion-only modified Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) criteria during the post-COVID-19 era, likely due to underlying lung parenchymal involvement in COVID-19 patients. Additionally, there was a 5.9% rise in high-probability scans, attributed to the hypercoagulability and vascular complications associated with COVID-19.

Multimodal Assessment and Intramodal Comparison of Imaging Techniques for Pediatric Pulmonary Vein Stenosis with Pulmonary Hypertension.

Pulmonary vein stenosis (PVS) is a rare, serious, and progressive disease in the pediatric population. Evaluation is complex and involves multimodality imaging. Diagnosis is important as early treatment to prevent progressive pulmonary hypertension and right ventricular dysfunction is essential. Adult studies have shown good correlation between various imaging modalities; however, there are limited data in children. This is a single-center retrospective pilot study to determine the reliability of measurement of pulmonary vein stenosis and pulmonary hypertension across different imaging modalities-computed tomography angiography (CTA), echocardiography (echo), lung perfusion scan (LPS), and cardiac catheterization (cath). PVS was defined as > 2mmHg by echo and cath and/or 50% reduction in diameter by CTA. Patients had to have an echo, CTA and cath performed within a 1-month timeframe of one another to be included in the study, with LPS data included if testing was completed at initial evaluation. Fifteen total patients were enrolled; 87% were categorized as primary PVS; a condition not directly related to direct injury or prior surgical intervention. Twenty-seven total stenotic pulmonary veins were identified (mean 1.8, range 1-4). CTA had a slightly better agreement with cath than echo in identifying PVS in different vein locations except in the LLPV. Additionally, echo and CTA had excellent sensitivity (91%) and specificity (100%) compared to cath for diagnosis of PH. We conclude that non-invasive imaging of echo and CTA has an acceptable correlation to cardiac catheterization for screening and initial evaluation of PVS and PH, as directly related to PVS, in pediatrics.

Short-and-medium term outcomes of Piccolo Device closure of patent ductus arteriosus in premature infants: A single center review

Introduction: Obstruction of the left pulmonary artery (LPA) or descending aorta requiring late intervention is a rare complication after transcatheter closure with Piccolo device, but a multidisciplinary approach is often needed to discover and manage the patient when it does occur. We report our center’s experience with the Piccolo device, including 3 cases of late LPA stenosis requiring surgical debridement and pulmonary artery plasty. Methods: Retrospective chart review of 60 patent ductus arteriosus closures using Amplatzer Piccolo device in premature infants. Results: 60 cases of device closure in premature infants. Transient LPA stenosis was noted in 8% of patients, LPA stenosis requiring surgical intervention in 5% of patients. LPA velocity of 2.7 m/s at any point following device placement by echocardiogram, and right pulmonary artery (RPA) to LPA ratio of 1.5 to 1 by 2D echo are predictive indicators of need for surgical intervention. Differential lung perfusion scans may also provide important prognostic and follow-up data after intervention. Conclusion: Transient LPA stenosis is expected after device closure of a patent ductus arteriosus in premature infants. A multidisciplinary approach and vigilant follow-up are required to discover late complications including LPA occlusion and manage the patient when it does occur.

Pulmonary Artery Angioplasty for Improving Ipsilateral Lung Perfusion in Adolescent and Adult Patients: An Analysis Based on Cardiac Magnetic Resonance Imaging and Lung Perfusion Scanning.

The left pulmonary artery (LPA) may be kinked and stenotic, especially in tetralogy of Fallot, because of ductal tissue and anterior deviation of the conal septum. If LPA stenosis is not effectively treated during total correction, surgical angioplasty is occasionally performed. However, whether pulmonary artery (PA) angioplasty in adolescents or adults improves perfusion in the ipsilateral lung remains unclear. This retrospective review enrolled patients who underwent PA angioplasty for LPA stenosis between 2004 and 2019. Among patients who underwent a lung perfusion scan (LPS) or cardiac magnetic resonance imaging (cMRI) pre- and post-pulmonary angioplasty, those aged >13 years with <40% left lung perfusion (p-left) in the pre-angioplasty study were included. Preoperative and postoperative computed tomography, LPS, and cMRI data were collected. The perfusion ratio was analyzed according to the LPA's anatomical characteristics. Seventeen adolescents and 16 adults (≥18 years old) were finally included (median age, 17 years). The most common primary diagnosis was tetralogy of Fallot (87.9%). In all patients, LPA angioplasty was performed concomitantly with right ventricular outflow tract reconstruction. No patients died. Preoperative p-left was not significantly different between adolescents and adults; however, adolescents had significantly higher postoperative p-left than adults. P-left significantly increased in adolescents, but not in adults. Seven patients had significant stenosis (z-score <-2.0) confined only to the proximal LPA and demonstrated significantly increased p-left. PA angioplasty significantly increased ipsilateral lung perfusion in adolescents. If focal stenosis is confined to the proximal LPA, PA angioplasty may improve ipsilateral lung perfusion, regardless of age.

Imaging in hepatopulmonary syndrome- case report. A multicenter approach during the coronavirus pandemic

A 60-year-old lady with alcoholic liver disease developed central cyanosis and orthodeoxia. A technetium-99m macro-aggregated albumin lung perfusion scan and contrast echocardiogram were performed. A 13% right to left shunt was calculated from the macro-aggregated albumin scan. There were more bubbles in the left heart than the right at the end of the contrast echocardiogram. Hepatopulmonary syndrome was therefore diagnosed. The patient had a liver transplant five days after these investigations. Further discussion about hepatopulmonary syndrome will be provided. Normally, macro-aggregated albumin scans are performed in few centers, however as this was at the height of the coronavirus pandemic, the scan needed to be performed locally to reduce the chance of the patient getting coronavirus. Local radiographers were remotely instructed on conducting the macro-aggregated albumin scan by a larger center to provide a timely and important investigation in a logistically difficult scenario.

Calculating Relative Lung Perfusion Using Fluoroscopic Sequences and Image Analysis: The Fluoroscopic Flow Calculator.

Maldistribution of pulmonary blood flow in patients with congenital heart disease impacts exertional performance and pulmonary artery growth. Currently, measurement of relative pulmonary perfusion can only be performed outside the catheterization laboratory. We sought to develop a tool for measuring relative lung perfusion using readily available fluoroscopy sequences. A retrospective cohort study was conducted on patients with conotruncal anomalies who underwent lung perfusion scans and subsequent cardiac catheterizations between 2011 and 2022. Inclusion criteria were nonselective angiogram of pulmonary vasculature, oblique angulation ≤20°, and an adequate view of both lung fields. A method was developed and implemented in 3D Slicer's SlicerHeart extension to calculate the amount of contrast that entered each lung field from the start of contrast injection and until the onset of levophase. The predicted perfusion distribution was compared with the measured distribution of pulmonary blood flow and evaluated for correlation, accuracy, and bias. In total, 32% (79/249) of screened studies met the inclusion criteria. A strong correlation between the predicted flow split and the measured flow split was found (R2=0.83; P<0.001). The median absolute error was 6%, and 72% of predictions were within 10% of the true value. Bias was not systematically worse at either extreme of the flow distribution. The prediction was found to be more accurate for either smaller and younger patients (age 0-2 years), for right ventricle injections, or when less cranial angulations were used (≤20°). In these cases (n=40), the prediction achieved R2=0.87, median absolute error of 5.5%, and 78% of predictions were within 10% of the true flow. The current study demonstrates the feasibility of a novel method for measuring relative lung perfusion using conventional angiograms. Real-time measurement of lung perfusion at the catheterization laboratory has the potential to reduce unnecessary testing, associated costs, and radiation exposure. Further optimization and validation is warranted.

Chronic thromboembolic pulmonary disease: Association with exercise-induced pulmonary hypertension and right ventricle adaptation over time

Background and AimChronic thromboembolic pulmonary disease (CTEPD) is a progressive condition caused by fibrotic thrombi and vascular remodeling in the pulmonary circulation despite prolonged anticoagulation. We evaluated clinical factors associated with CTEPD, as well as its impact on functional capacity, pulmonary haemodynamics at rest and after exercise, and right ventricle (RV) morphology and function. MethodsWe compared 33 consecutive patients with a history of acute pulmonary embolism and either normal pulmonary vascular imaging (negative Q-scan, group 1, n = 16) or persistent defects on lung perfusion scan (positive Q-scan) despite oral anticoagulation at 4 months (group 2, n = 17). Investigations included thrombotic load, the Pulmonary Embolism Severity Index (PESI) score, functional class, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), cardiopulmonary exercise test (CPET) and echocardiographic parameters at rest and after exercise (ESE), at 4 and at 24 months. ResultsCompared with group 1, group 2 featured a higher PESI score (p = 0.02) and a higher thrombotic load (p = 0.004) at hospital admission. At 4 months, group 2 developed exercise-induced pulmonary hypertension (Ex-PH) at CPET (p < 0.001) and ESE (p < 0.001). At 24 months group 2 showed higher NT-proBNP (p < 0.001), WHO-FC (p < 0.001), systolic (p<0.001) and diastolic (p = 0.037) RV dysfunction and worse RV-arterial coupling (p < 0.001) despite maintaining a low or intermediate echocardiographic probability of PH. ConclusionsThis is the first "proof of concept" study showing that patients with a positive Q-scan frequently develop Ex-PH and RV functional deterioration as well as reduced functional capacity, generating the hypothesis that Ex-PH could help detect the progression to CTEPD.

Abstract 11609: Developing a Novel Method for Measuring Relative Lung Perfusion at the Catheterization Laboratory

Background: Maldistribution of pulmonary blood flow (Qp) is common in patients with congenital heart disease and is associated with worse clinical outcomes. Currently, measurement of Qp-split can only be performed outside the catheterization laboratory, using either lung perfusion scans or cardiac magnetic resonance imaging. Aim: We sought to develop and evaluate a tool for measuring Qp-split using readily available fluoroscopy sequences. Methods: A retrospective cohort study of patients with conotruncal anomalies who underwent perfusion scan and subsequent cardiac catheterization. Inclusion criteria were non-selective angiogram of pulmonary vasculature, oblique angulation ≤20°, and an adequate view of both lung fields. A method was developed and implemented in 3D Slicer to calculate the amount of contrast that entered each lung field from the start of contrast-injection and until the onset of levophase. The predicted perfusion distribution was compared to the distribution measured by lung scan. Results: In total 32% (79/249) of screened studies met inclusion criteria. There was strong correlation between the predicted Qp-split and the measured Qp-split (R 2 =0.83, p&lt;0.001) with median absolute error (MAE) of 6%. Bias was not systematically worse at either extreme of flow distribution. Factors associated with better prediction were smaller BSA, younger age, right ventricle (vs. pulmonary artery) angiograms, and cranial angulations ≤20°. In cases with one or more of these conditions (n=40), the prediction achieved R 2 =0.87, MAE of 5.5%, and 78% of predictions were within 10% of true flow. Conclusions: Data from conventional angiograms can be used to provide accurate real-time measurement of relative perfusion of the left and right lungs. This has the potential to reduce unnecessary testing, associated costs, and radiation exposure.

Green synthesis, radioiodination and in vivo biodistribution of 5-(2-hydroxyphenyl)-2,4-dihydro-3H-pyrazol-3-one derivatives as potential candidates for lung imaging

Lung targeting was developed by synthesising pyrazolone derivatives 6a-f under solvent-free and thermal conditions by reacting azo coumarins 4a-c with hydrazines 5a and b using maltose as a biodegradable catalyst. Different spectral data characterized the synthesized agents as proton-NMR, FT-IR, and mass spectra. Direct radioiodination with iodine-131 was performed and optimized to reach the highest radiochemical purities (92 ± 0.47 to 98 ± 0.21%) using chloramine-T, a moderate oxidizing agent. The 131I-pyrazolone derivatives were confirmed based on HRMS. Furthermore, radioiodinated nitro-derivatives accumulated well in the lung of normal mice during in vivo evaluation, and the better uptake was for nitrophenyl-derivative 7f, about 30.06 ± 0.04% at 30 min after injection. Consequently, synthesized radioiodinated derivatives may be employed as prospective tracers for lung perfusion scans.

3D-Quantitated Single Photon Emission Computed Tomography/Computed Tomography: Impact on intended Management Compared to Lung Perfusion Scan in Marginal Candidates for Pulmonary Resection

ObjectivesBased on previous studies, single-photon emission computed tomography/computed tomography (SPECT/CT) has been proven more accurate and reproducible than planar lung perfusion scintigraphy to assess lobar perfusion. However, the impact of 3D-quantitated SPECT/CT on intended management in functionally marginal candidates for pulmonary resection is unknown. The evaluation of this impact was the main aim of this study. MethodsConsecutive candidates for lung resection underwent preoperative evaluation according to ERS/ESTS Algorithm and underwent preoperative lung perfusion imaging. The lobar contribution to the total lung perfusion was estimated using established planar scintigraphic methods and 3-dimensional quantitative SPECT/CT method (CT Pulmo3D and xSPECT-Quant, Siemens). The difference in estimated lobar perfusion with resulting changes in predicted postoperative (ppo) lung function and extent of lung resection were analyzed to reveal possible changes in operability. In-hospital outcome was assessed. ResultsOne hundred twenty patients (46 females) were enrolled. The mean age (±SD) of patients was 68 ± 9 years, target lesions were in upper lobes in 57.7% and in lower lobes in 33.5%. The median FEV1 (forced expiratory volume in 1 second) was 70.5% (IQR 52-84) and median DLCO (diffusion capacity of lung for carbon monoxide) was 56.6% [47.1-67.4]. The planar posterior oblique method, compared to 3D-quantitated SPECT/CT, underestimated the perfusion of upper lobes by a median difference of 5% (right [2-9], left [2.5-8]; P = <.0001), while it overestimated the perfusion of lower lobes (left by 4% [2-7], right by 6% [2-9]; P = <.0001). In contrast to planar scintigraphy-based evaluation, 4 patients (3.3%), all with upper lobe lesions, were classified as inoperable when 3D-quantitated SPECT/CT was used for calculation of the ppo lung function. ConclusionsIn selected patients with upper lobe lesions, 3D-quantitated SPECT/CT would have changed the treatment strategy from operable to inoperable. Importantly, postoperative mortality in this particular subgroup was disproportionally high. 3D-quantitated SPECT/CT shall be further evaluated as it might improve preoperative risk stratification in functionally marginal candidates.

Utility of 99mTc-MIBI myocardial perfusion imaging in the evaluation of cardiovascular complications in COVID-19 patients

The coronavirus disease is due to Acute Respiratory Syndrome Coronavirus2 (SARS-CoV-2). COVID-19 mainly affects the respiratory and immune systems and other organs like the cardiovascular and nervous systems, lungs, and kidneys (1). Several studies have reported COVID-19 patients with persistent symptoms for months after the initial phase. The most common symptoms are fatigue, headaches, cough, anosmia, arthralgia, and chest pain (2). Studies have shown this modality to diagnose, follow up, and evaluate response to treatment in chronic COVID-19 complications using 99mTc-MIBI myocardial perfusion single photon emission computed tomography (SPECT), pulmonary involvement with 99mTc-MAA perfusion lung scan, renal involvement with 99mTc-DTPA, and 99mTc-DMSA renal scintigraphy (3). Myocardial perfusion imaging with 99mTc-MIBI provides meaningful data to predict prognosis, risk of annual cardiac events, and evaluation of myocardium viability (4). Conventional SPECT Myocardial Perfusion Imaging (MPI) needs a viable metabolically active myocardial cell to extract the radiotracer. A review of articles shows that 99mTc-MIBI myocardial perfusion scintigraphy could be helpful in the timely acute myocardial infarction (MI) diagnosis and myocardial viability in COVID-19 patients. It is also beneficial in managing COVID-19 patients with heart failure by myocardial injury evaluation and choosing the best therapeutic choice, prognosis, and treatment response.

Prevalence of hepatopulmonary shunt in agitated saline test and lung perfusion scan and predictive value of arterial oxygenation

Sola Lee, Kwang-Woong Lee, Hyun Hwa Choi, Jiyoung Kim, Su young Hong, YoungRok Choi, Nam-Joon Yi, Kyung-Suk Suh, Jaewon Lee, Jae-Yoon Kim. Korean J Transplant 2022;36:391. https://doi.org/10.4285/ATW2022.F-5298

Prevalence of acute pulmonary thromboembolism in patients with COVID-19 related pulmonary involvement: A study of 240 lung perfusion scans

Prevalence of acute pulmonary thromboembolism in patients with COVID-19 related pulmonary involvement: A study of 240 lung perfusion scans

Interobserver Variability in Interpretation of VQ SPECT and its Impact on Patient Management

Background: Pulmonary Embolism (PE) is a major cause of morbidity, mortality and hospitalization. Ventilation Perfusion lung scan (VQ) is a powerful tool in diagnosing PE. It has been noted that there are some variations between highly experienced physicians in interpreting VQ SPECT due to lack of widely accepted reporting guidelines. Aim of the Study: Is to measure the interobserver variability in interpreting VQ scans, and then re-measure it again after applying standardized guidelines. Methods: Two cohorts of patients were included in this study the first included 347 patients and the second 290. Interobserver variability between 4 experienced physicians was measured on the first cohort and re-measured on the second cohort after applying 10 points agreed standardized guidelines. Results: Showed substantial increase in the percentage of agreement between all the physicians after applying the agreed 10 points standardized diagnostic criteria. This was apparent in all the categories with the highest agreement achieved when comparing 2 physicians. Kappa value increased from 0.346 to 0.4665 between the 4 Physicians, from low 0.3 to high 0.4 range between 3 Physicians and from as low as 0.2762 to the maximum of 0.5516 between 2 physicians. Unclassified number decreased between the 2 cohorts from 16.5% to 8% and subsequently decreasing false positive cases from 7.5% to 1.7%. Conclusion: Adherence to reporting guidelines increases the interobserver agreement in interpreting VQ SPECT leading to better patient outcomes and increased referrer confidence in reporting VQ SPECT.

A Brief Report on the Role of SPECT/TC in the Optimization of Radiotherapy Treatment with Radical Intent for Unresectable Stage III NSCLC

Background: The standard treatment for locally advanced non-small cell lung cancer (LA-NSCLC) is represented by concomitant chemo-radiotherapy followed by consolidation with durvalumab that ensures a 5-year survival of 46%. However, the risk of radiotherapy-induced pneumonia (RIP) is almost 10–15%. Complete cardiological examination is also usually performed during the cardiopulmonary pre-treatment evaluation and pulmonary function testing is one of the most used tool to predict the risk of RIP development. Aim: The aim of this study is to investigate the impact of Tc-99 macroaggregated albumin (MAA) lung perfusion scan with single photon emission-computed tomography/computed tomography (SPECT/CT) in the preliminary assessment of lung functions and its potential role for the optimization of the radiotherapy treatment planning. Methods: Descriptive and statistical analysis were performed on eight patients affected by unresectable stage III LA-NSCLC treated with chemo-radiotherapy. Before starting radiotherapy, patients underwent lung perfusion SPECT/CT. The SPECT/CT images were firstly co-registered with the simulation CT scan ones, then a specific region of interest (ROI) of lung volumes was created to represent the areas with a perfusion of at least 20% 40%, 60% and 80% of maximum perfusion, respectively. Finally, optimization of the standard treatment plan was performed with the aim of preserving the better perfused lung volumes. The dosimetric correlations of both plans were made comparing pulmonary V20 and V5, mean pulmonary, esophagus and heart dose. Results: From the DVH comparative analysis of the two treatment plans (standard one versus SPECT optimized one) obtained for each patient, the data confirmed an equal coverage of the target volume while respecting all lungs, heart and esophagus dose constraints. At the same time, SPECT-optimized plans allowed to reduce the average dose to the better perfused lung volumes. Conclusions: Lung perfusion scintigraphy could be considered a preliminary assessment tool to explore lung functions and stratify the risk of RIP development. SPECT/TC may also be proposed as a dose painting tool to optimize radiotherapy treatment plans. Only prospective analysis will be enable us to confirm the real reduction of RIP risk in lung areas with an optimal perfusion.

3D-quantitated lung perfusion SPECT/CT: Impact on intended management compared to lung perfusion scan in marginal candidates for lung resection surgery

Abstract Objective Based on previous studies, single-photon emission computed tomography/computed tomography (SPECT/CT) has been proven to be more accurate and reproducible than planar lung perfusion scintigraphy. We conducted a study to evaluate the impact of 3D-quantitated lung perfusion SPECT/CT on intended management in candidates for lung resection surgery. Methods Retrospective study including candidates for lung resection surgery with lung perfusion imaging. Patients underwent preoperative evaluation according to ERS/ESTS algorithm. The lobar contribution to the total lung perfusion was estimated using planar antero-posterior, posterior oblique and three-dimensional anatomical SPECT/CT method (CT Pulmo 3D and xSPECT- Quant, Siemens). The difference in lobar perfusion with resulting changes in the extent of lung resection were analyzed to reveal possible changes in operability. Results 120 patients (46 females) with known lung cancer or pulmonary lesion considered for resection with available lung perfusion scintigraphy and SPECT/CT were enrolled. The mean age (±SD) of patients was 68 ±9 years, the target lesions were located in upper lobe in 57.7% and in lower lobe in 33.5%. The median [IQR] FEV1 was 70.5% [52–84] and median DLCO 56.6% [47.1–67.4]. The planar posterior oblique method, compared to 3D-quantitated SPECT/CT, underestimated the perfusion of upper lobes by a median difference of 5% (right [2–9; IQR]; left [2.5–8], p= &amp;lt; 0.0001), while it overestimated the both lower lobes (left by 4% [2–7]; right by 6% [2–9], p= &amp;lt; 0.0001). In contrast to the planar scintigraphy based evaluation, 4(3.3%) patients with upper lobe lesions were classified as inoperable when 3D-quantitated SPECT/CT was used for calculation of predicted postoperative lung function. Conclusion In selected patients with upper lobe lesions, 3D-quantitated SPECT/CT would have changed the treatment strategy from operable to inoperable. Importantly, post-operative mortality in this particular subgroup was disproportionally high. 3D-quantitated SPECT/CT shall be further evaluated as it might improve preoperative risk stratification in marginal lung resection candidates.

Perfusion lung scans during the pandemic: COVID-19 experience in a large trauma hospital

PurposeTo evaluate the results of perfusion only lung scans and the frequency of necessary addition of the ventilation part of the scans to diagnose acute pulmonary embolism (PE) during Corona Virus Disease of 2019 (COVID 19) pandemic. Material and methodsWe retrospectively reviewed perfusion lung scans’ results between April to December 2020. The images were interpreted by two experienced nuclear medicine physicians as daily routine studies. Ventilation images were performed only if deemed necessary for accurate diagnosis of acute PE. ResultsA total of 128 lung perfusion scans in 127 patients were included. The scans were interpreted with certainty using the modified PIOPID criteria in 122 patients (95.3%). The results included low probability for acute PE in 110 patients (85.9%), normal in 6 patients (4.7%) and high probability of acute PE in 6 patients (4.7%). Ventilation imaging were performed in 4 patients with high probability, after negative testing for COVID19. The other 2 high probability results were confirmed clinically and with radiologic imaging. Only 6 scans (4.7%) were interpreted as intermediate perfusion scans, two of which due to inability to differentiate old from new perfusion defects in patients with chronic thromboembolic disease. Thus, the true indeterminate results due to the lack of ventilation scan were encountered in only 4 intermediate probability lung scans (3.1%). Thus, the total number of requested ventilation scans was 8 scans (6.2%) when considering both the high and intermediate probability interpretations. Six scans were performed (2 in the intermediate and 4 in the high probability scans). The two ventilation scans performed in the intermediate probability changed the diagnosis to low probability and the four performed in the high probability confirmed the initial interpretation of high probability scans by perfusion only. ConclusionThe ventilation part of lung scans is required only in a small number of patients for certain interpretation of the result. Perfusion lung scans are sufficient for evaluation of acute PE with certainty in most patients.