Lung Perfusion In Patients Research Articles

Imaging the pulmonary vasculature in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by a redistribution of regional lung perfusion that impairs gas exchange. While speculative, experimental evidence suggests that perfusion redistribution may contribute to regional inflammation and modify disease progression. Unfortunately, tools to visualize and quantify lung perfusion in patients with ARDS are lacking. This review explores recent advances in perfusion imaging techniques that aim to understand the pulmonary circulation in ARDS. Dynamic contrast-enhanced computed tomography captures first-pass kinetics of intravenously injected dye during continuous scan acquisitions. Different contrast characteristics and kinetic modeling have improved its topographic measurement of pulmonary perfusion with high spatial and temporal resolution. Dual-energy computed tomography can map the pulmonary blood volume of the whole lung with limited radiation exposure, enabling its application in clinical research. Electrical impedance tomography can obtain serial topographic assessments of perfusion at the bedside in response to treatments such as inhaled nitric oxide and prone position. Ongoing technological improvements and emerging techniques will enhance lung perfusion imaging and aid its incorporation into the care of patients with ARDS.

A technique for assessing pulmonary perfusion in patients with previously treated COVID-19 pneumonia: clinical controlled non-randomized study

INTRODUCTION: Evaluating pulmonary lung perfusion in patients with previously treated COVID-19 infection may lead to a better understanding of long-term consequences of the disease, as well as may identify the changes determined by their symptoms. Further research is required for optimization of lung perfusion’s design parameters’ methods in order to implement those in clinical practice.OBJECTIVE: To determine the possibilities of an alternative method for evaluation of relative lung perfusion using three-dimensional ultrafast contrast-enhanced MRI on patients with previously treated COVID-19 pneumonia.MATERIALS AND METHODS: We examined 100 patients (28 male and 72 female, aged 22 to 70) who had laboratory-confirmed COVID-19 infection. The research was conducted using the three-dimensional ultrafast dynamic contrast-enhanced MRI based on 3D T1-weighted images. During the postprocessing, we received the values of rPBF (relative pulmonary blood flow), rPBV (relative pulmonary blood volume), and rMTT (relative mean transit time).Statistics. For non-linear dependence modelling we used natural spline transformation for time and interaction effect with a group. Intergroup comparison on integral measures was based on Kruskall-Wallis test (χ2), pair comparisons were based on Conover’s test (Δ). For multiple hypothesis testing correction, we used the false discovery rate (FDR). Comparisons were determined as statistically significant when p<0.05.RESULTS: The differences in obtained values of lung perfusion among patient groups were confirmed both quantitatively (by rMTT, rPBV, rPBF) and qualitatively (by building the curves of contrast agent accumulation). Patients with previously treated COVID-19 demonstrate slower contrast agent transit and increased relative lung blood volume. Their accumulation curves have qualitative differences as well.DISCUSSION: We suggest a new method of evaluation of lung perfusion indicators in patients with previously treated COVID-19. We conducted an intergroup analysis based on the degree of lung damage during the acute phase of COVID-19 (with no infiltrativechanges, with minor lung damage, and major lung damage). The intergroup differences found are more significant for patients with lung damage (both minor and major) than for patients with no infiltrative lung changes during the acute phase of COVID-19.CONCLUSION: This method of evaluation of pulmonary perfusion is able to adequately characterize the functional lung conditions in patients with previously treated COVID-19 pneumonia. The chosen model is the most optimal.

Elexacaftor/Tezacaftor/Ivacaftor Improves Bronchial Artery Dilatation Detected by Magnetic Resonance Imaging in Patients with Cystic Fibrosis.

Rationale: Magnetic resonance imaging (MRI) detects improvements in mucus plugging and bronchial wall thickening, but not in lung perfusion in patients with cystic fibrosis (CF) treated with elexacaftor/tezacaftor/ivacaftor (ETI). Objectives: To determine whether bronchial artery dilatation (BAD), a key feature of advanced lung disease, indicates irreversibility of perfusion abnormalities and whether BAD could be reversed in CF patients treated with ETI. Methods: A total of 59 adults with CF underwent longitudinal chest MRI, including magnetic resonance angiography twice, comprising 35 patients with CF (mean age, 31 ± 7 yr) before (MRI1) and after (MRI2) at least 1 month (mean duration, 8 ± 4 mo) on ETI therapy and 24 control patients with CF (mean age, 31 ± 7 yr) without ETI. MRI was assessed using the validated chest MRI score, and the presence and total lumen area of BAD were assessed with commercial software. Results: The MRI global score was stable in the control group from MRI1 to MRI2 (mean difference, 1.1 [-0.3, 2.4]; P = 0.054), but it was reduced in the ETI group (-10.1 [-0.3, 2.4]; P < 0.001). In the control and ETI groups, BAD was present in almost all patients at baseline (95% and 94%, respectively), which did not change at MRI2. The BAD total lumen area did not change in the control group from MRI1 to MRI2 (1.0 mm2 [-0.2, 2.2]; P = 0.099) but decreased in the ETI group (-7.0 mm2 [-8.9, -5.0]; P < 0.001). This decrease correlated with improvements in the MRI global score (r = 0.540; P < 0.001). Conclusions: Our data show that BAD may be partially reversible under ETI therapy in adult patients with CF who have established disease.

Dynamic digital radiography: a novel quantitative modality to assess the pulmonary blood flow.

A 17-year-old girl with congenital unilateral absence of the pulmonary artery underwent surgical reconstruction of the right pulmonary artery (RPA) with a 6 mm polytetrafluoroethylene vascular graft 15 years ago. She had received stent implantation (S.M.A.R.T® 7.0 × 60 mm) to control the graft stenosis at 10-years-old. Nevertheless, regular hemodynamic assessment with balloon angioplasty was required because of the recurrence of graft stenosis. The current cardiac catheterization demonstrated RPA graft stenosis with a pressure gradient of 34 mmHg (Panel A). Tecnethium-99m-macroaggregated albumin lung perfusion scintigraphy showed decreased perfusion in the right lung (right/left: 20.1%/79.9%) (Panel B). A similar result was achieved in dynamic digital radiography (DDR) captured by a flat panel detector (Aero DR fine®, KONICAMINOLTA, Japan) and a conventional X-ray system (RAD speed Pro®, SHIMADZU, Japan), using a prototype workstation (KONICAMINOLTA, Japan) (right/left: 17.4%/82.6%). (Panel C, and Supplementary data online, Video) Lung perfusion scintigraphy has been a golden standard modality for the quantitative assessment of pulmonary blood flow laterality and is inevitably accompanied by radiation exposure. DDR is a new imaging to visualize small changes in pixel value representing the pulmonary circulation without contrast media.1,2 This imaging system can facilitate both qualitative and quantitative evaluations of the dynamic pulmonary circulation with a low cost, short examination time, and reduced radiation exposure. This convenient and non-invasive method will be an effective and alternative approach to assessing lung perfusion in patients with pulmonary artery stenosis.

Changes in Lung Perfusion in Patients Treated with Percutaneous Mechanical Thrombectomy for Intermediate-Risk Pulmonary Embolism

BackgroundCurrent pulmonary embolism treatment options rely heavily on anatomical clot location. However, anatomical location does not necessarily determine adverse outcomes; rather, clinical severity is secondary to the degree of perfusion impairment. Dual-energy computed tomography pulmonary angiogram (DE-CTPA) can map perfusion at the time of pulmonary embolism diagnosis. Single-photon emission computed tomography ventilation-perfusion scans allow for perfusion tracking similar to DE-CTPA. MethodsWe present 3 patients with intermediate-risk pulmonary embolism treated with mechanical thrombectomy using the Inari FlowTriever System (Inari Medical, Irvine, Calif). Lung perfusion scoring was applied to pre-procedure and post-procedure imaging. We graded perfusion of each lobe in 3 planes. If the entire lobe was perfused, a score of 3 was assigned. If lung perfusion is normal, total perfusion score is 15. All patients had pre-procedure and follow-up transthoracic echocardiograms. ResultsAll 3 patients were diagnosed with pulmonary embolism via DE-CTPA that showed right ventricle strain and had deep venous thrombosis. Following mechanical thrombectomy, patients immediately experienced improvement in perfusion score; scores continued to improve at follow-up. All patients also had improvement in right ventricle size or function on follow-up echocardiogram. DiscussionIntermediate-risk pulmonary embolism often has large initial clot burden that predicts residual pulmonary vascular obstruction. Residual pulmonary vascular obstruction is associated with increased risk of death, recurrent thrombus, and chronic thromboembolic pulmonary hypertension. Clot removal via thrombectomy may decrease the prevalence of residual pulmonary vascular obstruction by improving lung perfusion. We found that mechanical thrombectomy increased lung perfusion immediately and at follow-up assessments.

Lung perfusion scintigraphy in the assessment of pulmonary circulation after completion of surgical treatment of a hypoplastic left heart syndrome (HLHS).

Hypoplastic left heart syndrome (HLHS) is an inborn complex heart malformation. A multi-stage treatment is initiated in a neonatal period with a Norwood surgery. The next step is Glenn surgery - a bidirectional superior cavo-pulmonary anastomosis. At the last stage anastomosis of inferior vena cava (IVC) with the right pulmonary artery (RPA) is formed as a result of a Fontan surgery. The aim of this study was to assess lung perfusion in patients with HLHS after completion of a surgical therapy, using a scintigraphic method. In 92 patients with HLHS a planar lung scintigraphy in anterior and posterior projections after administration of 99mTc-macroaggregates in activity 18-111MBq was carried out twice (in several day intervals). At first, a radiopharmaceutical was administered to the right extremity in order to assess the lung distribution of blood flowing through the anastomosis of superior vena cava (SVC) with RPA. In the next study, after administration of the tracer to the right lower extremity, the distribution of blood flowing through the anastomosis of IVC with RPA was assessed. The relative percentage of each lung in the total lung perfusion was calculated on a Xeleris workstation using the "Lung perfusion analysis" program. Lung perfusion was considered close to symmetrical when the proportion was in the range of 40-60%. In spite of the fact that mean relative values of distribution of blood flowing through the anastomosis of SVC with RPA to the left lung (LL) and right lung (RL) in the entire study group did not differ significantly: LLmean = 47%; RLmean = 53%, p = 0.14, relative values of perfusion of both lungs were differentiated - in 26% of patients LL was better perfused, in 38% RL was better perfused and in 36% a perfusion of both lungs was similar. The analysis of blood distribution by anastomosis of IVC with RPA showed that the mean relative perfusion of RL was significantly higher than that of LL (70% vs. 30%, p < 0.0000001). No signs of pulmonary emboli were detected. In 13% of studied patients, uptake of the radiopharmaceutical in kidneys was shown indicating the presence of shunt "from right to left". After completion of surgical treatment of patients with HLHS, differentiated blood supply of the lungs was observed through SVC with RPA anastomosis and a tendency to higher blood supply of RL than LL by anastomosis of IVC with RPA. No signs of pulmonary embolism were detected. The study revealed a "right to left" shunt in some patients.

Multicenter Phase II Clinical Trial of Isolated Lung Perfusion in Patients With Lung Metastases

Up to 66% of patients show local pulmonary disease progression after pulmonary metastasectomy. Regional treatment with isolated lung perfusion (ILuP) may improve local control with minimal systemic adverse effects. The aims of this study were to evaluate local and distant control after ILuP, determine the effect on overall survival compared with historical controls, and confirm the safety and feasibility of ILuP. A total of 107 patients with resectable pulmonary metastases of colorectal carcinoma, osteosarcoma, and soft-tissue sarcoma were included in a prospective phase II study of pulmonary metastasectomy combined with ILuP with 45 mg melphalan at 37°C. Local and distant control, overall survival, lung function, and 90-day mortality and morbidity were monitored. We report 0% mortality, low morbidity, and no long-term pulmonary toxicity. For colorectal carcinoma, median time to local pulmonary progression, median time to progression, and median survival time were 31, 14, and 78 months, respectively. Median time to local progression was not reached for sarcoma, whereas median time to progression and median survival time were 13 and 39 months, respectively. The 5-year disease-free rate and pulmonary progression-free rate were 26% and 44% for colorectal carcinoma and 29% and 63% for sarcoma, respectively. ILuP with melphalan combined with metastasectomy is feasible and safe. Compared with historical controls, favorable results were obtained in this phase II study for local control. Further evaluation of locoregional lung perfusion techniques with other chemotherapeutic drugs is warranted.

Subtraction CT angiopulmonographic assessment of the vascular bed and lung perfusion in patients with chronic thromboembolic pulmonary hypertension: A pilot study

To evaluate the vascular bed and lung perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH) by computed tomography (CT) and to compare the severity of pulmonary arterial (PA) thrombotic lesions concurrent with parenchymal perfusion disorders with angiopulmonographic findings and clinical and hemodynamic characteristics. In the period from November 2015 to May 2016, 22 patients (7 men, 15 women) aged 27 to 67 years with a verified diagnosis of CTEPH were examined using an Aquilion ONE VISION Edition 640 (Toshiba Medical Systems, Japan) CT scanner with a 320-row detector. Perfusion defect in this study was evaluated with the new software allowing one to combine contrast and contrast-free images by a subtraction method. CT data analysis included visual assessment of the vascular bed and lung parenchyma and quantitative assessment with perfusion map construction and semi-automatic determination of the obstruction index (OI) and perfusion defect index (PDI). OI was compared with PDI and mean LA pressure according to the data of right heart catheterization and 6-minute walk test. A statistically significant correlation was found between OI and PDI in patients with CTEPH (Pearson r=0.56; p=0.0065). There were no relationships between mean LA pressure and vascular perfusion indices (OI and PDI) or between vascular perfusion parameters and 6-minute walk test results. CT angiopulmonography in conjunction with pulmonary perfusion assessment (within one study) allows evaluation of the severity of vascular lesions and perfusion disorders and determination of the efficiency of treatment in patients with CTEPH.

Non-contrast-enhanced preoperative assessment of lung perfusion in patients with non-small-cell lung cancer using Fourier decomposition magnetic resonance imaging

ObjectiveTo investigate non-contrast-enhanced Fourier decomposition MRI (FD MRI) for assessment of regional lung perfusion in patients with Non-Small-Cell Lung Cancer (NSCLC) in comparison to dynamic contrast-enhanced MRI (DCE MRI). MethodsTime-resolved non-contrast-enhanced images of the lungs were acquired prospectively in 15 patients using a 2D balanced steady-state free precession (b-SSFP) sequence. After non-rigid registration of the native image data, perfusion-weighted images were calculated by separating periodic changes of lung proton density at the cardiac frequency using FD. DCE MRI subtraction datasets were acquired as standard of reference. Both datasets were analyzed visually for perfusion defects. Then segmentation analyses were performed to describe perfusion of pulmonary lobes semi-quantitatively as percentages of total lung perfusion. Overall FD MRI perfusion signal was compared to velocity-encoded flow measurements in the pulmonary trunk as an additional fully quantitative reference. ResultsImage quality ratings of FD MRI were significantly inferior to those of DCE MRI (P<0.0001). Sensitivity, specificity, and accuracy of FD MRI for visual detection of perfusion defects were 84%, 92%, and 91%. Semi-quantitative evaluation of lobar perfusion provided high agreement between FD MRI and DCE MRI for both entire lungs and upper lobes, but less agreement in the lower parts of both lungs. FD perfusion signal showed high linear correlation with pulmonary arterial blood flow. ConclusionFD MRI is a promising technique that allows for assessing regional lung perfusion in NSCLC patients without contrast media or ionizing radiation. However, for being applied in clinical routine, image quality and robustness of the technique need to be further improved.

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.

TU‐G‐217A‐01: Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE‐MRI) for High‐Resolution Lung Perfusion Evaluation in Pulmonary Neoplasms Prior to Radiotherapy

Purpose: To propose using Dynamic Contrast Enhanced‐ MRI (DCE‐MRI) for a high‐resolution, pre‐treatment evaluation of lung perfusion in patients with lung cancer who will receive radiation therapy. The second goal is to benchmark the performance of DCE‐MRI against the gold standard: scintigraphy perfusion‐scan. Methods: DCE‐MRI and scintigraphy V/Q scans were acquired for 4 lung cancer patients prior to radiation therapy. DCE‐MRI relies on a single bolus injection of a paramagnetic contrast agent (Gd‐DTPA) that produces a transient signal enhancement on a T1 sensitive imaging sequence. By mapping the signal changes into contrast agent concentration curves, one can use techniques developed for indicator dilution to calculate perfusion estimates of pulmonary blood flow (PBF), blood volume, and mean transit time. The images were corrected for volumetric changes induced by respiratory motion using a non‐rigid registration technique. 3D masks of the right and left lung fields were manually contoured on the initial MRI volume using MATLAB and applied to the PBF maps. These maps were subsequently collapsed in the A‐P‐ dimension to create coronal 2D projections consistent with the scintigraphy V/Q images. Left and right lung fields were divided into 3 sections of equal height, and signal intensity computation was carried out analogous to the analyses performed on scintigraphy scans. Kendall's tau rank correlation coefficients were used to compare lung perfusion estimated using DCE‐MRI to the perfusion portion of the V/Q studies. Results: The non‐parametric Kendall's tau correlation coefficient ranged between 0.93–0.96 for PBF and scintigraphy perfusion. There is a 2X improvement in spatial resolution when compared to SPECT‐perfusion. Conclusions: There was a strong correlation between the DCE‐MRI and scintigraphy V/Q estimates of perfusion with statistically significant rank correlations. These results indicate that DCE‐MRI is a viable high‐resolution imaging modality for the evaluation of pre‐treatment lung perfusion in patients with lung cancer.

Prospective Study on Functional Results After Lung-Sparing Radical Pleurectomy in the Management of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) can reduce lung function by entrapping lung parenchyma via a rind of tumor with or without concurrent effusion. Radical pleurectomy (RP) allows expansion of the trapped lung. The purpose of this study was to investigate changes in pulmonary function and lung perfusion in patients undergoing RP. In a prospective, nonrandomized study, all patients with histologically proven MPM were evaluated from January to December 2010 for trimodality therapy including RP as surgical procedure. Pulmonary-function tests and perfusion scans were obtained before and 2 months after RP. Primary end points were pulmonary function (forced vital capacity [FVC], forced expiratory volume in 1 second [FEV1]) and ipsilateral lung perfusion. Sixteen out of 25 consecutive patients (age 68.8±8.9 years) were enrolled in the study. Macroscopic complete resection could be achieved in 13 patients (81.3%). Diaphragm resection was necessary in 5 patients. Significant postsurgical improvement of pulmonary function at 2 months was observed for FVC and FEV1 (both absolute and percentage of predicted values) and ipsilateral perfusion (p < 0.001). Avoidance of diaphragm resection was associated with greater increase in FVC (+34.6±17.0% versus +13.5±5.4%; p = 0.002) and FEV1 (+29.2±18.1% versus +12.1±6.4%; p = 0.015), respectively. Lung-sparing RP leads to significant improvement of pulmonary function and perfusion after a recovery time of 2 months. Functional results are better after preservation of the diaphragm. Preservation of physiological reserve via lung-sparing RP might allow patients with MPM to be eligible for further therapeutic options in the long term.

Noninvasive evaluations of pulmonary circulation, cardiac function, and liver excreting rate at late follow-up following the modified Fontan operation

The purpose of this paper was to define the late postoperative pulmonary circulation and cardiac and liver functions after a modified Fontan operation by radionuclide studies. Eleven patients (5 with single ventricle and 6 with double outlet right ventricle) underwent a modified Fontan operation using a RA-PA anastomosis. These 11 patients ranging in age from 7 to 42 years (mean 17±10 years) were examined at 4.7–12.1 years (mean 8.6±2.4 years) postoperatively and compared with studies in 10 normal adults. Pulmonary circulation, cardiac function and liver excreting function were determined by intravenous administration of Tc-MAA, Tc-PYP, and Tc-PMT, respectively. No extrapulmonary radioactivity was detected by Tc-MAA lung perfusion in patients. Although the cardiac diastolic function of the patients remained normal, the systolic functions (EF=46.4±7.8%, 1/3EF=11.2±4.4%, PER=1.93±0.54/sec) of the patients were significantly decreased compared with those of normal controls (EF=54.7±4.7%, 1/3EF=21.7±2.1%, PER=2.91±0.4/sec), respectively. The mean level of MTT of the patients (9.4±2.7 minutes) was also significantly prolonged compared with that of normal controls (6.1±4.4 minutes). Some of these deteriorated parameters clearly related to higher age at operation and length of intervals since operation. These data suggest that the earlier surgical intervention by the Fontan operation is desired for the complex congenital cardiac anomalies.

Assessment of pulmonary vascular volume and lung perfusion in patients with hypoplastic left heart syndrome (HLHS) in Fontan-circulation

Data from catheter angiography indicate that children with Hypoplastic Left Heart Syndrome (HLHS) in Fontan circulation have hypoplastic central pulmonary arteries. We used novel MRI techniques to quantify pulmonary vascular volume and lung perfusion in a cohort of HLHS patients and a group of healthy control subjects.

Impaired lung perfusion in patients with congestive heart failure by quantitative MRI perfusion

Methods Study subjects were prospectively enrolled and underwent cardiac MRI at 1.5 T. First-pass perfusion was performed with 0.01 mmol/kg gadopentetate in 3 coronal slices covering anterior, mid and posterior lung fields during inspiration using a saturation recovery SSFP sequence. Mean signal intensity of all pixels in pulmonary parenchyma at each time point was evaluated using a custom modelindependent deconvolution program for perfusion quantitation. Pulmonary transit time was measured as the time interval between peak signal intensity in the main pulmonary artery and peak signal intensity in the left atrium. Cardiac function was assessed using SSFP standard short axis cine imaging. Pulmonary flow was measured by through plane phase contrast imaging in the main pulmonary artery. Results Of the 25 subjects enrolled 7 were normal controls and 15 were patients with systolic CHF in I-III NYHA functional class who completed lung perfusion imaging in inspiration. Average lung perfusion was reduced in CHF patients, 81 ± 32 ml/100 ml/min vs 118 ± 48 ml/100 ml/min in controls (p = 0.046). Similar to normal controls patients with CHF maintained a perfusion gradient in the gravity direction with the highest perfusion in posterior and the lowest in anterior lung field. However, the absolute perfusion was reduced in all lung fields with anterior, mid and posterior perfusion 58 ± 26, 85 ± 38, 106 ± 36 ml/100 ml/min in CHF patients and 73 ± 53, 116 ± 53, 165 ± 45 ml/100 ml/min in controls. Reduced lung perfusion was associated with lower pulmonary flow (indexed by BSA) (r = -0.771, p < 0.001), longer pulmonary transit time (r = -0.729, p < 0.001), a marker of total pulmonary resistance, lower LVEF (r = 0.443, p = 0.039) and lower RVEF (r = 0.474, p = 0.026). In a multivariate regression analysis including all variables associated with lung perfusion and an interaction term for pulmonary flow and pulmonary transit time since they were significantly correlated, the predictors of lung perfusion were pulmonary flow and flow/transit time interaction, suggesting the importance of both forward flow and total pulmonary resistance.

Lung Perfusion in Patients With Pulmonary Hypertension: Comparison Between MDCT Pulmonary Angiography With minIP Reconstructions and 99mTc-MAA Perfusion Scan

Alterations in lung perfusion are a well-known feature of pulmonary hypertension (PH) seen on nuclear medicine studies. Abnormal radiotracer distribution in patients with PH may be caused by arterial thromboembolic occlusion, like in chronic thromboembolic pulmonary hypertension, by parenchymal destruction as in interstitial lung disease and pulmonary emphysema or by distal arteriopathy, like in idiopathic pulmonary arterial hypertension and other nonembolic forms. The different imaging pattern on radionuclide perfusion studies represents an important element for differential diagnosis. The aim of this study was to evaluate minimum intensity projection (minIP) images as an alternative to perfusion scintigraphy. We compared lung parenchyma attenuation patterns as depicted in minIP reconstructions with scintigraphic findings of lung perfusion in patients affected by pulmonary hypertension from various etiologies. One hundred and seven consecutive patients affected by PH of different etiology (37 of those had chronic thromboembolic pulmonary hypertension) who had undergone both multidetector computed tomography pulmonary angiography and 99mTc-MAA perfusion scan were included. Five-millimeter thickness contiguous axial, coronal, and sagittal minIP images were reconstructed from the contrast enhanced computed tomography datasets. Two radiologists evaluated the images and qualitatively graded pulmonary attenuation as homogeneous, inhomogeneous with nonsegmental patchy defects, or inhomogeneous with segmental defects. The presence of parenchymal and pleural alterations was recorded. MinIP perfusion grading results were then compared with those of perfusion scintigraphy. In 87 of 107 patients (81.3%), the attenuation pattern seen on minIP images (39 homogeneous patterns, 13 with nonsegmental patchy defects, and 39 with segmental defects) correlated with the nuclear medicine scans. In the remaining 20 patients (18.7%), the imaging pattern was discordant because of 7 false-positive and 2 false-negative thromboembolic patterns at minIP and 11 false-positive thromboembolic patterns at perfusion scan. Air-trapping and parenchymal disease caused false-positive findings at minIP and perfusion scans, respectively. The sensitivity and specificity of minIP in detection of a chronic thromboembolic perfusion pattern were 94.5% and 90%, whereas perfusion scan had 100% sensitivity and 84% specificity. MinIP reconstructions can identify different patterns of pulmonary parenchymal attenuation, which show high concordance with perfusion patterns seen on radionuclide studies in patients with pulmonary hypertension. MinIP is a promising technique to evaluate lung perfusion in PH and may be used as an alternative to scintigraphy in the diagnostic work-up of these patients.

Doppler flow evaluation can anticipate abnormal left lung perfusion after transcatheter closure of patent ductus arteriosus

Coil protrusion into the left pulmonary artery (LPA) has been described after transcatheter closure of the patent ductus arteriosus (PDA). The possible impact of such a finding in lung perfusion has not been completely clarified. We evaluated Doppler flow velocities and lung perfusion in patients submitted to that procedure. After transcatheter closure of PDA with coils, 70 patients (mean age 8.6+/-3.4 years) were followed for a period of 3.6+/-0.9 years (range 2.1-5.9) and compared to 22 controls. Peak flow velocities and coil protrusion were assessed by Doppler echocardiography. A Doppler velocity index (DVI) was calculated by the difference between the LPA and right pulmonary artery (RPA) peak flow velocities relative to the pulmonary trunk (PT) expressed in percentage, as follows: DVI=(LPA velocity - RPA velocity)/PT velocity x 100. Lung scintigraphy was performed using (99m)Tc-labelled macro-aggregated albumin. Device protrusion was observed in 94% of the patients, 10% of whom presented abnormal left lung perfusion. Peak LPA velocity and DVI were significantly greater in patients (p=0.001) and correlated negatively with left lung perfusion values (R(2)=0.21 and R(2)=0.65, respectively). A cut-off value of 50% for the DVI showed high sensitivity and specificity for reduced lung perfusion. Impaired left lung perfusion may appear following transcatheter closure of PDA with coils and the determination of DVI may anticipate such alteration.

Noninvasive evaluations of pulmonary circulation, cardiac function, and liver excreting rate at late follow-up following the modified Fontan operation

The purpose of this paper was to define the late postoperative pulmonary circulation and cardiac and liver functions after a modified Fontan operation by radionuclide studies. Eleven patients (5 with single ventricle and 6 with double outlet right ventricle) underwent a modified Fontan operation using a RA-PA anastomosis. These 11 patients ranging in age from 7 to 42 years (mean 17 ± 10 years) were examined at 4.7–12.1 years (mean 8.6 ± 2.4 years) postoperatively and compared with studies in 10 normal adults. Pulmonary circulation, cardiac function and liver excreting function were determined by intravenous administration of Tc-MAA, Tc-PYP, and Tc-PMT, respectively. No extrapulmonary radioactivity was detected by Tc-MAA lung perfusion in patients. Although the cardiac diastolic function of the patients remained normal, the systolic functions (EF = 46.4 ± 7.8%, 1/3EF = 11.2 ± 4.4%, PER = 1.93 ± 0.54/sec) of the patients were significantly decreased compared with those of normal controls (EF = 54.7 ± 4.7%, 1/3EF = 21.7 ± 2.1%, PER = 2.91 ± 0.4/sec), respectively. The mean level of MTT of the patients (9.4 ± 2.7 minutes) was also significantly prolonged compared with that of normal controls (6.1 ± 4.4 minutes). Some of these deteriorated parameters clearly related to higher age at operation and length of intervals since operation. These data suggest that the earlier surgical intervention by the Fontan operation is desired for the complex congenital cardiac anomalies.