Lung Perfusion Imaging Research Articles

Unexpected Diagnosis of Thyroid Storm in a Young Child Referred for Urgent Lung Perfusion Imaging

A 2-year-old girl with cardiorespiratory distress and suspected pulmonary embolism (PE) was referred for urgent lung perfusion scintigraphy, proven negative for perfusion defects but unexpectedly revealing an enlarged orthotopic thyroid. This finding was, under the circumstances, considered as suggestive of thyroid storm (TS), subsequently confirmed by thyroid hormones measurement. A (99m)TcO(4)(-) thyroid scan 1 week later showed a homogenously enlarged thyroid with high tracer uptake. Both PE and TS are rare but serious pediatric conditions with partially overlapping presentations. In the present case, the unbounded (99m)Tc fraction avidly taken by the overfunctioning thyroid suggested the correct, clinically unsuspected, diagnosis.

Magnetic Resonance Imaging of Cystic Fibrosis Lung Disease

Lung involvement in cystic fibrosis (CF) disease continues to be a major life-limiting factor of this autosomal recessive genetic disorder. Efforts made toward early diagnosis and advances in therapy have led to sustained survival of affected patients, and many are now of adult age. Because imaging provides detailed information on regional distribution of CF lung disease, repetitive imaging is required for severity assessment and therapy monitoring not only in clinical routine but also for interventional trials. Computed tomography has long succeeded chest radiograph because it provides the highest morphologic detail of airway and parenchymal changes. This is inseparably accompanied by an increase in radiation exposure to CF individuals, who are critically susceptible to, and may accumulate, relevant doses during their lifetime. Magnetic resonance imaging (MRI) as an ionizing radiation-free cross-sectional imaging modality is capable of depicting anatomic hallmarks of CF lung disease at lower spatial resolution but with enhanced tissue characterization. Comprehensive functional lung imaging (imaging of respiratory mechanics, ventilation, and lung perfusion) provides valuable additional information that cannot or can hardly be obtained by any other single diagnostic procedure. The present review article strives to present the current state of lung MRI in CF, as well as its future perspectives. Functional MRI of the CF lung is at the threshold of being considered a routine application, which, supporting early diagnosis, may help to further improve the survival of CF patients.

Spect-guidance to Reduce Radioactive Dose to Functioning Lung for Stage III Non-small Cell Lung Cancer

To investigate the treatment effect of additional information obtained by single photon emission computed tomography (SPECT) lung perfusion imaging (LPI) in the radiotherapy planning process for patients with stage III non-small cell lung cancer (NSCLC). 39 patients with stage III NSCLC were enrolled. Gross tumor volume (GTV) was outlined by SPECT/CT images, SPECT-LPIs being used to define functional lung (FL) and non-functional lung (NFL) regions. Two sets of IMRT plans were designed to deliver 64Gy to PTV. One was a regular IMRT plan using CT images only (Plan 1), and the other was a corresponding IMRT plan using co-registered images (Plan 2). FLVx (the % volume of functional lung receiving ≥x Gy) and WLVx (% volume of whole lung to receive ≥x Gy) were compared by paired Student's t test. Kendalls correlation was used to analyze the factor (s) related with the FLV20 decrease. Compared with plan 1, both WLVx and FLVx were decreased in plan 2. WLV10, WLV15, WLV20, WLV25, WLV30 and WLV35 decreased 9.7%, 13.8%, 17.2%, 12.9%, 9.8% and 9.8%, and FLV10, FLV15, FLV20, FLV25, FLV30 and FLV35 decreased 10.8%, 14.6%, 17.3%, 14.5%, 14.5% and 10.5%. FLVx decreased significantly compared with WLVx. There were significant differences in WLV10, WLV15, WLV20, WLV25, WLV3 and FLV10, FLV15, FLV20, FLV25, FLV30 between plan 1 and plan 2 (P=0.002, 0.000, 0.000, 0.005, 0.027 and 0.002, 0.000, 0.000, 0.006, 0.010). According to Kendall correlation analysis, NFL had a negative relation with the percentage FLV20 decrease (r=-0.559, P<0.01), while the distance of PTV and NFL center had a significantly positive relation with the percentage of FLV20 decrease (r=0.768, P<0.01). Routine use of SPECT-LPI for patients undergoing radiotherapy planning for stage III NSCLC appears warranted.

The clinical application of combined dual-energy CT pulmonary angiography and indirect venography

Objective To assess the usefulness of combined dual-energy CT pulmonary angiography (DE-CTPA) and indirect CT venography (CTV) in the diagnosis of venous thromboembolism (VTE) . Methods Forty-nine patients with leg swelling suspected of pulmonary embolism (PE) underwent both DE-CTPA combined with CTV and lower extremity venous ultrasound (US) in 1—2 days prior to CT.Image quality of CTPA and dual energy lung perfusion image (DEPI) was rated using a 5-point scale and the coherence between CTPA and DEPI was analyzed by Kap pa statistics.The ability of CTV and US in the diagnosis of deep venous thrombosis (DVT) was compared by Chi-square test. Results Twenty-nine of 49 patients were identified with PE by DE-CTPA,including 28 patients identified by CTPA and one more by DEPI,and 21 patients were found to have both PE and DVT.Both DE-CTPA and DEPI had positive findings for pulmonary embolism in 19 patients and both had negative findings in 18 patients.There was a moderate agreement between DEPI and DE-CTPA in the assessment of PE (Kappavalue=0.7534).Thirty-eight patients with DVT were identified by US,while 35 patients were identified by CTV.Among the 35 patients with DVT identified by CTV,pelvic veins were involved in 25 patients,while the inferior vena cava was involved in 3 patients.There was no significant difference between CTV and US in the diagnosis of DVT (P=0.625).The detection rate of VTE with DE-CTPA combining CTV was 30.6% higher than that with CTPA alone. Conclusions The combined DE-CTPA and CTV achieves“one-stop”examination.It not only provides evaluation of PE and DVT and increases detection of VTE,but also depicts perfusion defect of pulmonary parenchyma that corresponds to PE. Key words: Pulmonary embolism; Venous thrombosis; Lower extremity; Phlebography; Tomography,X-ray computed

Cationised radiolabelled nanoparticles for perfusion imaging of the lungs

Diagnostic imaging of the blood perfusion of the lungs is currently performed using particles of macro-aggregated albumin, which are mechanically arrested at limiting diameters of the capillary bed. While the proportion of blood flow obstructed is typically very low and temporary, it would seem more desirable to image lung perfusion in patients using a non-obstructive method, and using materials that avoid biological hazards. We have characterised the in vitro and in vivo properties of a colloid of a cationised radiolabelled nanocomposite. The nanoparticles comprise a Technetium-99m core encapsulated in graphitic carbon, and coated with low molecular weight poly-lysine to provide a strong charge-based affinity for the endothelial glycocalyx of the lung. Following intravenous injection in rabbits and cats, the nanoparticles rapidly distribute and localise in the lungs, thus enabling gamma camera imaging of lung perfusion. Repeat administration of this colloid in both species over several weeks indicates favourable biocompatibility.

Preclinical characterization of 18F-MAA, a novel PET surrogate of 99mTc-MAA

(99m)Tc-labeled macroaggregated albumin ((99m)Tc-MAA) scintigraphy scan is routinely performed for lung perfusion imaging and for the assessment of in vivo distribution of (90)Y-labeled SIR-Spheres prior to selective internal radiation treatment for hepatocellular carcinoma. Positron emission tomography (PET) imaging is superior to gamma scintigraphy in terms of sensitivity, spatial resolution and accuracy of quantification. This study reported that (18)F-labeled macroaggregated albumin ((18)F-MAA) is an ideal PET imaging surrogate for (99m)Tc-MAA. (18)F-MAA was prepared from the commercial MAA kit via a one-step conjugation with N-succinimidyl 4-(18)F-fluorobenzoate ((18)F-SFB). The biodistribution study and microPET/microSPECT imaging were conducted in normal SD rats after intravenous injection of (18)F-MAA/(99m)Tc-MAA. A comparison study of these two radiotracers was performed after co-injection via the intrahepatic arterial in a N1S1 hepatoma-bearing SD rat model. The optimal condition for (18)F-MAA preparation is coupling MAA (0.5mg) with (18)F-SFB at 45°C for 5 min in a phosphate buffer of pH 8.5. (18)F-MAA was prepared in 60 min with high radiochemical yield (30%-35%) and high radiochemical purity (>95%). The in vivo distribution of (18)F-MAA after intravenous injection meets the specifications of MAA depicted in European Pharmacopeia. Our study demonstrated excellent correlation between (18)F-MAA and (99m)Tc-MAA in the regional distribution of tumor, liver and lungs (R(2)=0.965, 0.886 and 0.991, respectively), and also in the tumor-to-liver and tumor-to-lungs ratio (R(2)=0.965 and 0.987, respectively) in a N1S1 hepatoma-bearing SD rat model. The organ uptakes derived from animal PET/CT and SPECT/CT imaging after administration of these two tracers were in accordance with those obtained in the distribution studies. Starting from commercial MAA kit, an efficient preparation of (18)F-MAA was successfully established. Highly correlated, almost parallel, regional distribution of (18)F-MAA and (99m)Tc-MAA in both normal rats and hepatoma-bearing rats was observed. The findings, taken together, demonstrate that (18)F-MAA is an ideal surrogate for (99m)Tc-MAA for clinical PET applications.

Phase I Study of Pemetrexed, Cisplatin, and Concurrent Radiotherapy in Patients With Locally Advanced Non-small Cell Lung Cancer

Concurrent chemoradiotherapy in well-selected locally advanced non-small cell lung cancer (LANSCLC) is considered as standard therapy. However, the choice of anticancer agents is still unresolved. Our objectives were to determine the maximum tolerated dose and recommended dose of pemetrexed in combination with cisplatin, with concurrent late course accelerated hyperfractionated (LCAF) intensity modulated radiotherapy (IMRT) in patients with LANSCLC and to investigate the safety and efficacy. The chemotherapy was cisplatin (25 mg/m(2) × 3 days) plus pemetrexed with doses escalating from 400 to 500 mg/m(2). The dose level was increased every 3 patients. The gross tumor volumes of concurrent LCAF IMRT were delineated according to [(18)F] fluorodeoxyglucose positron emission tomography computed tomography imaging. To spare functional lung, single photon emission photography lung perfusion imaging was used to optimize the plans. The total radiation dose was limited such that the V20 of bilateral lung is no more than 35%. Nine patients with LANSCLC were enrolled in this study. The median radiation dose was 70.8 Gy. The response rate was 66.7% with a complete remission rate of 33.3%. Toxicity was mild with only 1 patient experiencing dose limiting toxicity in 500 mg/m(2) level. Obviously, the maximum tolerated dose was not reached as per the definition. As the systemically active chemotherapy dose was reached, further dose escalation was discontinued, and the recommended dose of pemetrexed for a phase II study was 500 mg/m(2). The combination of pemetrexed and cisplatin with concurrent LCAF IMRT optimized based on single photon emission photography lung perfusion imaging is well tolerated in patients with LANSCLC. Full therapeutic doses of the chemotherapy can be safely administered. The initial results showed signs of efficacy.

Utility of CMR in identification of post lung transplant cardiovascular complications

Background Graft dysfunction after lung transplantation is typically attributable to infection or rejection. In the absence of these entities, structural cardiovascular (CV) abnormalities need to be sought. At our center this evaluation typically includes a myriad of diagnostic tests: echocardiography, chest computed tomographic angiography, nuclear medicine lung perfusion imaging, and right heart catheterization (RHC). This study was designed to evaluate the utility of a novel comprehensive CMR protocol for identification of all post-operative structural CV complications in lung transplant recipients. Methods We enrolled 80 consecutive lung transplant recipients who were referred for CMR evaluation of CV abnormalities. There were 47 men and 33 women; mean age 56.7 ±13.6 years; 55 Caucasians, 9 Hispanic, 13 African American, and 3 Asian. Underlying restrictive disease was present in 39 subjects, obstructive disorders in 22, and other disorders in 19. Forty-three subjects had undergone double lung transplant, while 37 subjects had single lung transplant (23 left lung, and 14 right lung). The comprehensive CMR protocol included complete short and long axis cine imaging (SSFP) to evaluate cardiac size and function; ECG gated spin echo imaging to assess pericardial thickness; contrast enhanced MRA of the pulmonary arterial (PA) and venous (PV) systems to assess for anastomotic site stenosis; phase contrast velocity flow mapping to assess anastomotic site peak velocity and right and left PA flow fraction; and inversion recovery SSFP to evaluate for myocardial fibrosis. Results All 80 subjects completed CMR imaging without difficulty and none were excluded from this analysis for reasons of image quality. The mean LVEF was 66.4±9.23%, mean RVEF was 54.37±10.45%, right and left PAs flow were 2.6±1.21 and 2.6± 1.31 liter/min, respectively. Specific complications identified and the prevalence is shown in Table 1. Patients with moderate or severe PA or PV anastomotic site stenosis underwent RHC and intravascular ultrasound, which confirmed CMR findings; patients with severe stenosis underwent stenting of the respective vessel. Patients with CMR evidence of pericardial constriction underwent pericardiectomy with improvement in symptoms. Conclusions A comprehensive CMR protocol can be a useful single noninvasive test for the detection of structural cardiovascular (CV) abnormalities after lung transplantation. Funding Not applicable.

Effects of respiratory cycle and body position on quantitative pulmonary perfusion by MRI

To evaluate the performance of lung perfusion imaging using two-dimensional (2D) first pass perfusion MRI and a quantitation program based on model-independent deconvolution algorithm. In eight healthy volunteers 2D first pass lung perfusion was imaged in coronal planes using a partial Fourier saturation recovery stead state free precession (SSFP) technique with a temporal resolution of 160 ms per slice acquisition. The dynamic signal in the lung was measured over time and absolute perfusion calculated based on a model-independent deconvolution program. In the supine position mean pulmonary perfusion was 287 ± 106 mL/min/100 mL during held expiration. It was significantly reduced to 129 ± 68 mL/min/100 mL during held inspiration. Similar differences due to respiration were observed in prone position with lung perfusion much greater during expiration than during inspiration (271 ± 101 versus 99 ± 38 mL/min/100 mL (P < 0.01)). There was a linear increase in pulmonary perfusion from anterior to posterior lung fields in supine position. The perfusion gradient reversed in the prone position with the highest perfusion in anterior lung and the lowest in posterior lung fields. Lung perfusion imaging using a 2D saturation recovery SSFP perfusion MRI coupled with a model-independent deconvolution algorithm demonstrated physiologically consistent dynamic heterogeneity of lung perfusion distribution.

SU‐C‐BRC‐04: Avoidance of Perfused Lung by Optimization of Functional Mean Dose in Direct Machine Parameter Optimization

Purpose: To implement and evaluate a functional mean dose‐based objective in a well‐established IMRT system, using lung perfusion images and direct machine parameter optimization (DMPO). Methods: Nineteen patients underwent SPECT perfusion imaging prior to treatment. In this retrospective study, plans were generated using Pinnacleˈ DMPO (Philips Healthcare, Andover, MA) with the aim of minimizing either the mean lung dose (MLD) or the lung functional mean dose (FMD). A seven equidistant beam configuration was used in all plans. Two levels of dose were prescribed: 50 Gy to the PTV1 (clinical target volume with margins) and 66 Gy to the PTV2 (gross tumor volume with margins). The MLD or FMD objective was decreased by steps of 1 Gy until dose to target volumes or organs at risk was deemed unacceptable. Plans were compared in terms of dose‐volume and dose‐function parameters. Statistical significance was assessed with a Wilcoxon matched pairs test. Results: While keeping PTV coverage similar (volumes receiving 93% of the prescribed dose were all over 98%), differences in MLD between both types of plans for a given patient ranged from –1.0 to +1.5 Gy (p = 0.2050), while FMD decreased significantly with a range of –2.1 to 0.0 Gy (p = 0.0003). The net improvement (FMD difference − MLD difference) ranged between −2.2 and 0.0 Gy. Dose to other organs at risk were similar and below widely‐ accepted tolerances. Conclusions: The use of SPECT perfusion images in conjunction with DMPO allowed a significant decrease of FMD while keeping dose to other structures at an acceptable level. Functionality‐aware dose redistribution could prove useful for dose escalation to improve tumor control with similar or lower lung complication probabilities. The approach can also be easily ported to arc therapy treatment planning using SmartArc.This work is supported by the Natural Sciences and Engineering Research Council of Canada and by a research agreement with Philips Healthcare.

Imaging of acute pulmonary embolism using a dual energy CT system with rapid kVp switching: Initial results

PurposeComputed tomography pulmonary angiography (CTPA) is considered as clinical gold standard for diagnosing pulmonary embolism (PE). Whereas conventional CTPA only offers anatomic information, dual energy CT (DECT) provides functional information on blood volume as surrogate of perfusion by assessing the pulmonary iodine distribution. The purpose of this study was to evaluate the feasibility of lung perfusion imaging using a single-tube DECT scanner with rapid kVp switching. Materials and methodsFourteen patients with suspicion of acute PE underwent DECT. Two experienced radiologists assessed the CTPA images and lung perfusion maps regarding the presence of PE. The image quality was rated using a semi-quantitative 5-point scale: 1 (=excellent) to 5 (=non-diagnostic). Iodine concentrations were quantified by a ROI analysis. ResultsSeventy perfusion defects were identified in 266 lung segments: 13 (19%) were rated as consistent with PE. Five patients had signs of PE at CTPA. All patients with occlusive clots were correctly identified by DECT perfusion maps. On a per patient basis the sensitivity and specificity were 80.0% and 88.9%, respectively, while on a per segment basis it was 40.0% and 97.6%, respectively. None of the patients with a homogeneous perfusion map had an abnormal CTPA. The overall image quality of the perfusion maps was rated with a mean score of 2.6±0.6. There was a significant ventrodorsal gradient of the median iodine concentrations (1.1mg/cm3 vs. 1.7mg/cm3). ConclusionLung perfusion imaging on a DE CT-system with fast kVp-switching is feasible. DECT might be a helpful adjunct to assess the clinical severity of PE.

The study on dual-energy lung perfusion imaging in the diagnosis of pulmonary embolism using dualsource CT

Objective To explore the diagnostic values of dual energy lung perfusion in the diagnosis of pulmonary embolism by using dual-source CT (DSCT). Methods Thirty patients with clinically suspected pulmonary embolism underwent dual-energy scanning with dual-source CT. The scanned data were integrated into three groups including 140, 80 kV and coefficient of 0.3. According to the CT pulmonary angiography (CTPA) of the fusion data, the patients were divided into pulmonary embolism group and normal group. The thin-slice reconstruction of data was analyzed using dual-energy perfusion imaging analysis software. The lung field was divided into upper, middle and lower part to make quantitative analysis of lung tissue perfusion. Paired t-tests were used in the normal patients to compare bilateral lungs, and independent samples t-tests were applied to compare the embolism group and normal group, while minimum intensity projection images (MinIP) were utilized in the assessment of lung ventilation. Results Dual energy CT showed symmetrical homogeneous perfusion in 16 normal cases, without significant perfusion defects. Quantitative analysis showed that left and right lung perfusion were (27 ± 7) and (28 ± 8 ) HU respectively, and no significant difference was found between the two sides ( t=-1.73, P ＞0.05 ).Perfusion of the left upper, middle and lower lung was ( 23 ± 6), (24 ± 6), and (28 ± 8) HU respectively, while the perfusion of right upper, middle and lower lung was (26 ±8), (27 ±8), and (28 ±9) HU respectively, showing no statistical significant difference between the two sides (t=-1.91, -1.96,-1.73 ,P＞0.05 ). Angiography of pulmonary embolism group(14 cases)showed filling defects in the pulmonary trunk, segments and sub-segments. Pulmonary perfusion imaging showed low perfusion or defectsin lung field that dominated by embolic vessels. Quantitative analysis showed that the perfusion of the whole lung and the middle and lower lung were (22 ±5), (22 ±8), and (21 ±8) HU in the embolism group,which were significantly different from the normal group (t=-2. 10, -2.32, -2.63, P＜0.05).Minimum intensity projection images showed a good consistency of abnormal ventilation zone area and perfusion abnormalities. Conclusions Pulmonary perfusion status, especially pulmonary embolism, can be analyzed by dual energy CT scanning. It helps to early discover and precisely locate the embolism. Key words: Pulmonary embolism; Perfusion; Tomography,X-ray computed

Value of SPECT lung perfusion imaging in the optimization of intensity-modulated radiotherapy for non-small cell lung cancer

放射性肺损伤已成为肺癌患者放疗剂量提升的重要限制因素，特别是对于合并慢性阻塞性肺疾病、重度吸烟等导致肺功能减损的患者。依据单光子发射计算机断层扫描肺灌注显像（single photon emission computed tomography—lungperfusion images，SPECT—LPI）优化放疗计划，

Dual Energy CT lung perfusion imaging—Correlation with SPECT/CT

Aims were (1) to determine the diagnostic accuracy of Dual Energy CT (DECT) in the detection of perfusion defects and (2) to evaluate the potential of DECT to improve the sensitivity for PE. 15 patients underwent Dual Energy pulmonary CT angiography (DE CTPA) and a combination of lung perfusion SPECT/CT and ventilation scintigraphy. CTPA and DE iodine distribution maps as well as perfusion SPECT/CT and inhalation scintigrams were reviewed for pulmonary embolism (PE) diagnosis. DECT and SPECT perfusion images were assessed regarding localization and extent of perfusion defects. Diagnostic accuracy of DE iodine (perfusion) maps was determined with reference to SPECT/CT. Diagnostic accuracies for PE detection of DECT and of SPECT/CT with ventilation scintigraphy were calculated with reference to the consensus reading of all modalities. DE CTPA had a sensitivity/specificity of 100%/100% for acute PE, while the combination of SPECT/CT and ventilation scintigraphy had a sensitivity/specificity of 85.7%/87.5%. For perfusion defects, DECT iodine maps had a sensitivity/specificity of 76.7% and 98.2%. DECT is able to identify pulmonary perfusion defects with good accuracy. This technique may potentially enhance the diagnostic accuracy in the assessment of PE.

Syndrome hépatopulmonaire et pneumopathie interstitielle diffuse idiopathique

The association between interstitial pneumonia and hepatopulmonary syndrome (HPS) has rarely been described. We report the cases of two patients, 62 and 64 years old, who presented with idiopathic interstitial pneumonia (IIP) and severe, disproportionate hypoxemia, PaO(2) 42 and 47 mmHg, respectively. This hypoxemia lead to search for associated disease. The diagnosis of right-to-left shunt was established by the 99mTc-MAA perfusion lung imaging. A contrast cardiac echography confirmed the intrapulmonary shunt. Both patients were found to have hepatic cirrhosis, classed as Child Grade A6 and C10. In this context of chronic hepatopathy, the diagnosis of SHP associated with IIP was established. Liver transplantation, the only way to cure the lung consequences of the HPS, was planned. These two cases highlight the importance of searching for right-to-left shunt in patients who have lung disease with severe disproportionate hypoxemia. Liver transplantation is the only way to cure the lung consequences of the hepathopathy. The rare association between ILD and HPS raises problems when deciding to go forward to transplantation in the absence of a histological diagnosis of the lung disease and where the prognosis of the lung disease is unclear.

Comparative study of dual-energy CT pulmonary angiography and lung perfusion with pulmonary perfusion scintigraphy in the diagnosis of pulmonary embolism

Objective To investigate the diagnostic value of dual-energy CT pulmonary angiography (DE-CTPA) and dual-energy CT lung perfusion (DE-CTLP) in the assessment of pulmonary embolism comparing with pulmonary ventilation-perfusion scintigraphy. Methods Fifty patients suspected of PE (26 males, 24 females) underwent both DE-CTPA, DE-CTLP and pulmonary ventilation-perfusion scintigraphy. The results were compared and the correlation between the intravascular clots in DE-CTPA and the perfusion defects in DE-CTLP was analyzed. The sensitivity, specificity and accuracy of DE-CTLP for PE were assessed according to scintigraphic results which was considered as a gold standard. Result ( 1 ) Of 50 cases,920 segments in 46 cases were diagnostable, 4 cases were not included because of the poor image quality. lntravascular clots were found in 262 segments on DE-CTPA and perfusion defects in 266 segments were identified on DE-CTLP, while 268 segments were positive on scintigraphy. (2) The perfusion defects on DE-CTLP were correlated well with the clots on CTPA ( r = 0. 883, P < 0. 01 ). The Dual energy CT Lung perfusion imaging had a good consistence with scintigraphy (Kappa = 0. 940, P <0. 01 ). The sensitivity, specificity, positive and negative predictive value were 96. 2% (279/290), 98.0%(641/654), 95. 5% (279/292) and 98. 3% (641/652), respectively. (3)The radiation dose of DE-CTPA and CE-CTLP scan was(4. 37 ± 0. 47) mSv by using CareDose 4D technique. Conclusion DE-CTPA and CE-CTLP can provide pulmonary vascular morphology and parenchyma perfusion information which are useful and valuable for the diagnosis of PE. Key words: Pulmonary embolism; Tomography,X-ray computed; Perfusion; Radionuclide imaging

Radiopharmaceutical considerations for using Tc-99m MAA in lung transplant patients

ObjectivesTo elucidate radiopharmaceutical considerations for using technetium Tc-99m albumin aggregated (Tc-99m MAA) in lung transplant patients and to establish an appropriate routine dose and preparation procedure. SettingTertiary care academic hospital during May 2007 to May 2009. Practice descriptionNuclear pharmacist working in nuclear medicine department. Practice innovationRadiopharmaceutical considerations deemed important for the use of Tc-99m MAA in lung transplant patients included radioactivity dose, particulate dose, rate of the radiolabeling reaction (preparation time), and final radiochemical purity. Evaluation of our initial 12-month experience, published literature, and professional practice guidelines provided the basis for establishing an appropriate dose and preparation procedure of Tc-99m MAA for use in lung transplant patients. Main outcome measuresRadiochemical purity at typical incubation times and image quality in subsequent lung transplant patients imaged during the next 12 months. ResultsBased on considerations of radioactivity dose, particulate dose, rate of the radiolabeling reaction (preparation time), and final radiochemical purity, a routine dose consisting of 3mCi (111 MBq) and 100,000 particles of Tc-99m MAA for planar perfusion lung imaging of adult lung transplant patients was established as reasonable and appropriate. MAA kits were prepared with a more reasonable amount of Tc-99m and yielded high radiochemical purity values in typical incubation times. Images have continued to be of high diagnostic quality. ConclusionTc-99m MAA used for lung transplant imaging can be readily prepared with high radiochemical purity to provide a dose of 3mCi (111 GBq)/100,000 particles, which provides images of high diagnostic quality.

Lung Perfusion Imaging with Monosized Biodegradable Microspheres

After intravenous injection, particles larger than red blood cells will be trapped in the first capillary bed that they encounter. This is the principle of lung perfusion imaging in nuclear medicine, where macroaggregated albumin (MAA) is radiolabeled with (99m)Tc, infused into a patient's arm vein, and then imaged with gamma scintigraphy. Our aim was to evaluate if monosized microspheres could replace (99m)Tc-MAA. Biodegradable poly(L-lactide) microspheres containing chelating bis(picolylamine) end groups were prepared by a flow focusing method on a microfluidic glass chip and were of highly homogeneous size (9.0 +/- 0.4 microm). The microspheres were radiolabeled with [(99m)Tc(H(2)O)(3)(CO)(3)](+) and then evaluated in mice for lung perfusion imaging. Fifteen minutes after injection, 79.6 +/- 3.8% of the injected activity was trapped in the lungs of mice. Monosized biodegradable radioactive microspheres are, thus, appropriate lung perfusion imaging agents. Other sizes of these highly uniform microspheres have the potential to improve diagnostic and therapeutic approaches in diverse areas of medicine.

A method for registration between CT and single photon emission computed tomography lung perfusion images

Objective To compare the registration errors of single photon emission computed tomography (SPECT) and CT images using a visual method and the methods of different numbers and combinations of the external markers,and to explore an accurate,reproducible and simple registration method of CT-SPECT lung perfusion images. Methods Two patients with lung cancer underwent thoracic CT scans and SPECT lung perfusion scans. The 9 external markers were fixed on the thoracic region before CT scans and SPECT lung per-fusion scans. Two series of images were registered using a visual method and the methods of different numbers and combinations of the external markers respectively based on Pinnacle~3 planning treatment system. After regis-tration , space coordinates of the 9 external markers were recorded respectively. The accuracy of registration was assessed using the absolute differences value of the 9 external markers coordinates between two series of images after registration. Results After registration using 9 external markers, the error in the left-right direction was the greatest, (1. 92 ±1.56 ) mm. Compared with that of using 9 external markers, there were statistical differ-ences using the visual method,2 external markers,3 external markers,4 external markers ( P < 0. 05 ), and there was no statistical difference using 5 external makers,6 external markers,7 external markers,8 external markers (P =0.081,0.061,0. 854,0. 860, respectively). Comparing the registration methods based on the middle thoracic external markers with the registration methods based on the pectus external markers using 4 ex-temal markers,5 external markers,6 external markers,there was no statistical difference between two methods and between the former and 9 external markers ( P =0.395,0. 110, respectively), and there was statistical difference between the latter and 9 external markers ( P = 0. 010). There was no statistical difference in the three registrations using 5 external markers ( P =0. 613,0. 26,0. 531 ,respectively). Conclusion The method of 5 external markers distributing non-coplanar is an accurate, reproducible and simple registration method of CT-SPECT lung perfusion images. Choosing the middle thoracic external markers less influenced by respiratory movement is a better method. Key words: Carcinoma, non- small- cell lung; Radiotherapy; Tomography, emission-computed, single-photon; Medical image registration

Ventilations-Perfusions-Lungen -szintigraphie mit der PET und 68Ga-markierten Radiopharmaka

Imaging of lung perfusion with positron emission tomography (PET) is already possible with 68Ga labeled denaturized albumin. The purpose of our study was to produce and test a 68Ga labeled aerosol (Galligas®) for ventilation and 68Ga labeled albumin particles (microspheres) for perfusion imaging with PET. Galligas was produced by simmering and burning generator eluted 68Ga solution (100 MBq/0.1 ml) in an ordinary technegas generator. Fifteen patients with suspicion on pulmonary embolism underwent PET/CT (Biograph 16) after inhalation of Galligas and application of 68Ga labeled microspheres. A low dose CT was acquired for attenuation correction (AC). Images were reconstructed with and without AC. The inhaled activity was calculated compared to the activity injected. Inhaled radioaerosol Galligas demonstrated typical distribution as known from 99mTc-labeled technegas with homogeneous distribution in lung without hilar deposits. Attenuation corrected images resulted in artefacts in the lung base. Therefore, non-corrected images were used for making the results. Three out of fifteen patients showed a deficient perfusion whereas ventilation was normal corresponding to pulmonary embolism. Lung scintigraphy with PET is feasible. Galligas is simple to produce (analogously to technegas). 68Ga labeled microspheres are available. The method is applicable to daily routine and rendered clinically relevant informations.