Three-dimensional fractal analysis of 99mTc-MAA SPECT images in chronic thromboembolic pulmonary hypertension for evaluation of response to balloon pulmonary angioplasty: association with pulmonary arterial pressure

The Role of Lung Ventilation/Perfusion Scan in the Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH), which is classified as a group 4 pulmonary hypertension (PH), is a life-threatening complication of acute pulmonary embolism (PE). With the introduction of multidisciplinary approaches and innovative treatment strategies for CTEPH, it is currently regarded not as a fatal disease, but as a curable form of PH. Ventilation/perfusion (V/Q) scan is the preferred imaging method for screening for CTEPH, with superior sensitivity to CT pulmonary angiography. The findings and interpretations of V/Q scan in CTEPH may differ from those observed in acute PE. The use of V/Q scan in combination with SPECT or SPECT/CT is becoming more popular than planar scan alone. Comprehensive understanding of the role of V/Q scan in CTEPH will assist in providing early diagnosis, proper therapeutic decision making, and improved prognosis. This review outlines the current roles and potential clinical applications of V/Q scan in the diagnosis and evaluation of CTEPH.

Cardiothoracic Imaging for Outcome Prediction in Chronic Thromboembolic Pulmonary Hypertension after Pulmonary Endarterectomy or Balloon Pulmonary Angioplasty: A Scoping Review

There has been a rapid expansion in centers performing balloon pulmonary angioplasty (BPA) and pulmonary thromboendarterectomy (PTE) for chronic thromboembolic pulmonary hypertension (CTEPH). The purpose of this scoping review was to identify cardiothoracic imaging predictors of outcomes and to identify gaps to address in future work. A scoping review was conducted using the framework outlined by Arksey and O'Malley and Levac et al. in MEDLINE and EMBASE. The study protocol was preregistered in OSF Registries and performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR) guidelines. There were 1117 identified studies, including 48 involving pulmonary thromboendarterectomy (n = 25) and balloon pulmonary angioplasty (n = 23). CT was the most common preoperative imaging modality used (n = 21) and CT level of disease was the most reported imaging predictor of outcomes for pulmonary thromboendarterectomy. Although must studies evaluated hemodynamic improvements, imaging was of additional use in predicting clinically significant procedural complications after balloon pulmonary angioplasty, as well as mortality and long-term outcome after pulmonary endarterectomy. Predictors reported in MRI and digital subtraction angiography were less commonly reported and warrant multicenter validation. Cardiothoracic imaging may predict clinically significant outcomes after balloon pulmonary angioplasty and pulmonary thromboendarterectomy. Radiologists involved in the assessment of CTEPH patients should be aware of key predictors and future investigations could focus on multicenter validation and new technologies.

Semi-Quantitative Analysis of Lung Perfusion SPECT/CT for Evaluation of Response to Balloon Pulmonary Angioplasty in Chronic Thromboembolic Pulmonary Hypertension

Purpose

We aimed to investigate the response to balloon pulmonary angioplasty (BPA) in chronic thromboembolic pulmonary hypertension (CTEPH) using semi-quantitative analysis of lung perfusion SPECT/CT.

Methods

This is a single-center retrospective study of patients with CTEPH who underwent BPA and pre- and post-BPA lung perfusion SPECT/CT between 2015 and 2022. Segmental defects on SPECT/CT were visually assessed and semi-quantitatively scored as 1 (large defect) or 0.5 (moderate defect) in accordance with modified PIOPED II criteria. The perfusion defect score was defined as (Σ segmental defect scores/18) × 100 (%). Associations between perfusion defect score and hemodynamic or functional parameters including WHO functional class, six-minute walking distance (6MWD), serum B-type natriuretic peptide (BNP), mean arterial pulmonary pressure (mPAP), pulmonary vascular resistance (PVR), and tricuspid regurgitation pressure gradient (TRPG) on echocardiography were statistically analyzed.

Results

A total of 24 consecutive patients were included. The perfusion defect score significantly improved after BPA (median 58.3% vs. 47.2%, P < 0.001), in conjunction with the WHO functional class, 6MWD, serum BNP, mPAP, and TRPG. Perfusion defect scores were significantly correlated with 6MWD (rho = - 0.583, P < 0.001), serum BNP (rho = 0.514, P < 0.001), mPAP (rho = 0.583, P < 0.001), and PVR (rho = 0.575, P < 0.001). The improvement in the perfusion defect score was significantly associated with improvement in mPAP (rho = 0.844, P < 0.001).

Conclusion

Our results suggest that semi-quantitative analysis of lung perfusion SPECT/CT can provide a potential imaging biomarker for monitoring the efficacy of BPA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-024-00858-1.

Evaluation of balloon pulmonary angioplasty using lung perfusion SPECT in patients with chronic thromboembolic pulmonary hypertension

BACKGROUND

The aim of this study was to evaluate the effect of balloon pulmonary angioplasty (BPA) using lung perfusion single-photon emission computed tomography (SPECT) in patients with chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS AND RESULTS

20 consecutive patients (64 ± 15 years) who were diagnosed with CTEPH and underwent BPA were included in this study. All patients underwent lung perfusion SPECT before and after BPA. The relationship between functional %volume of the lung calculated from the lung perfusion SPECT (FVL-LPSPECT), and other clinical parameters before and after BPA was assessed using the Wilcoxon signed-rank test. The correlation between each parameter and mean pulmonary artery pressure (mPAP) using the Spearman's correlation was performed. To determine predictors of mPAP for evaluating treatment effectiveness, significant parameters were included in multiple regression analysis. After BPA, world health organization functional classification, six-minute walk distance (6MWD), mPAP, and FVL-LPSPECT significantly improved. FVL-LPSPECT (r = - 0.728, P < 0.001) and 6MWD (r = - 0.571, P = 0.009) were significant correlation of mPAP. In the multiple regression analysis, FVL-LPSPECT was the most significant predictor of improvement in mPAP after BPA (P < 0.001).

CONCLUSIONS

This study demonstrated that the lung perfusion SPECT could be a potential measurement of the effectiveness of BPA in patients with CTEPH.

Ventilation/perfusion imaging predicts response to balloon pulmonary angioplasty in patients with chronic thromboembolic pulmonary hypertension

OBJECTS

Although balloon pulmonary angioplasty (BPA) has emerged as an alternative treatment option for chronic thromboembolic pulmonary hypertension (CTEPH), it is followed in some patients by residual PH. We studied the efficacy of BPA on pulmonary blood flow and the predictive value of ventilation/perfusion (V/Q) scanning.

METHODS

We retrospectively reviewed the clinical database, which included patients diagnosed with CTEPH who had received BPA. All patients undergone V/Q scanning to quantify the extent of pulmonary perfusion abnormality before and after BPA. Pulmonary hemodynamics were assessed by right heart catheterization, and cardiac function and exercise capacity were evaluated at baseline and post-BPA. A total of 120 CTEPH patients were included for analysis.

RESULTS

BPA significantly alleviated mean pulmonary arterial pressure (mPAP: 48.0 ± 12.9 mmHg vs 34.7 ± 10.3 mmHg, P < 0.001) and pulmonary vascular resistance (PVR: 8.8 ± 4.1 Wood units vs 5.2 ± 3.0 Wood units, P < 0.001), and improved cardiac function (N-terminal pro B-type natriuretic peptide: 1628.7 ± 2887.2 pg/mL vs 400.4 ± 669.3 pg/mL, P < 0.001) and exercise capacity (6-minute walking distance: 386 ± 122 m vs 461 ± 86 m, P < 0.001). The extent of pulmonary perfusion abnormality represented by the percentage of perfusion defects (PPDs%) was improved after BPA (50.1 ± 13.6 vs 35.6 ± 14.2, P < 0.001), with the right and inferior lung lobes benefitting the most. PPDs% < 35.5 at baseline and greater restoration of PPDs% after BPA (∆PPDs% > 20.6) were associated with a better response to BPA (PPDs% < 35.5: odds ratio [OR] 10.857, 95% confidence interval [95%CI] 1.393-84.635, P = 0.023; ∆PPDs% > 20.6: OR 1.035, 95% CI 1.002-1.068, P = 0.036).

CONCLUSION

BPA significantly restored pulmonary blood flow, predominantly in the right and inferior lobes. V/Q scanning has the potential to predict the therapeutic response to BPA for CTEPH.

Imaging of Pulmonary Hypertension in Adults: A Position Paper from the Fleischner Society

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure greater than 20 mm Hg and classified into five different groups sharing similar pathophysiologic mechanisms, hemodynamic characteristics, and therapeutic management. Radiologists play a key role in the multidisciplinary assessment and management of PH. A working group was formed from within the Fleischner Society based on expertise in the imaging and/or management of patients with PH, as well as experience with methodologies of systematic reviews. The working group identified key questions focusing on the utility of CT, MRI, and nuclear medicine in the evaluation of PH: (a) Is noninvasive imaging capable of identifying PH? (b) What is the role of imaging in establishing the cause of PH? (c) How does imaging determine the severity and complications of PH? (d) How should imaging be used to assess chronic thromboembolic PH before treatment? (e) Should imaging be performed after treatment of PH? This systematic review and position paper highlights the key role of imaging in the recognition, work-up, treatment planning, and follow-up of PH. This article is a simultaneous joint publication in Radiology and European Respiratory Journal. The articles are identical except for stylistic changes in keeping with each journal's style. Either version may be used in citing this article. © 2021 RSNA and the European Respiratory Society. Online supplemental material is available for this article.

Pulmonary angioplasty: A step further in the continuously changing landscape of chronic thromboembolic pulmonary hypertension management

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially fatal and frequently undiagnosed form of pulmonary hypertension (PH), classified within group 4 by the World Health Organization (WHO). It is a type of precapillary PH, which uncommonly develops as a peculiar sequel of acute pulmonary embolism due to the partial resolution of the mechanically obstructing thrombus with a coexisting inflammatory response from pulmonary vessels. CTEPH is one of the potentially treatable forms of PH whose current standard of care is surgical pulmonary endarterectomy. Medical therapy with few drugs in non-operable disease is approved and has shown improvement in patients' hemodynamic condition and functional ability. Recently, balloon pulmonary angioplasty (BPA) has shown promising results as a treatment option for technically inoperable patients, those with unacceptable risk-to-benefit ratio and in a case of residual PH after endarterectomy. Lack of meticulous CTEPH screening programs in post-pulmonary embolism patients leading to underdiagnosis of this condition, complex operability assessment, and diversity in BPA techniques among different institutions are still the issues that need to be addressed. In this paper, we review the recent achievements in the management of non-operable CTEPH, their outcome and safety, based on available data.

Advanced Imaging in Pulmonary Vascular Disease

Although the diagnosis of pulmonary hypertension requires invasive testing, imaging serves an important role in the screening, classification, and monitoring of patients with pulmonary vascular disease (PVD). The development of advanced imaging techniques has led to improvements in the understanding of disease pathophysiology, noninvasive assessment of hemodynamics, and stratification of patient risk. This article discusses the current role of advanced imaging and the emerging novel techniques for visualizing the lung parenchyma, mediastinum, and heart in PVD.

Imaging of pulmonary hypertension in adults: a position paper from the Fleischner Society

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure greater than 20 mmHg and classified into five different groups sharing similar pathophysiologic mechanisms, haemodynamic characteristics, and therapeutic management. Radiologists play a key role in the multidisciplinary assessment and management of PH. A working group was formed from within the Fleischner Society based on expertise in the imaging and/or management of patients with PH, as well as experience with methodologies of systematic reviews. The working group identified key questions focusing on the utility of CT, MRI, and nuclear medicine in the evaluation of PH: a) Is noninvasive imaging capable of identifying PH? b) What is the role of imaging in establishing the cause of PH? c) How does imaging determine the severity and complications of PH? d) How should imaging be used to assess chronic thromboembolic PH before treatment? e) Should imaging be performed after treatment of PH? This systematic review and position paper highlights the key role of imaging in the recognition, work-up, treatment planning, and follow-up of PH.

Perfusion Scintigraphy in Diagnosis and Management of Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a life-threatening complication of acute pulmonary embolism (PE). Because the treatment of CTEPH is markedly different from that of other types of pulmonary hypertension, lung ventilation-perfusion (V/Q) scintigraphy is recommended for the workup of patients with unexplained pulmonary hypertension. Lung V/Q scintigraphy is superior to CT pulmonary angiography for detecting CTEPH. Perfusion defect findings of CTEPH can be different from those of acute PE. Familiarity with the patterns of perfusion defects seen during the initial workup of CTEPH and the expected posttreatment changes seen at follow-up imaging is essential for accurate interpretation of V/Q scintigraphy findings. ^©RSNA, 2019.

Novel imaging techniques in pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension is a life-shortening condition, which may be idiopathic but is more frequently seen in association with other conditions. Current guidelines recommend cardiac catheterization to confirm the diagnosis of pulmonary hypertension. Evidence suggests an increasing role for noninvasive imaging modalities in the initial diagnostic and prognostic assessment and evaluation of treatment response.

RECENT FINDINGS

In this review we examine the evidence for current noninvasive imaging methodologies: echocardiography computed tomography and MRI in the diagnostic and prognostic assessment of suspected pulmonary hypertension and explore the potential utility of modeling and machine-learning approaches.

SUMMARY

Noninvasive imaging allows a comprehensive assessment of patients with suspected pulmonary hypertension. It plays a key part in the initial diagnostic and prognostic assessment and machine-learning approaches show promise in the diagnosis of pulmonary hypertension.

Comparative clinical and predictive value of lung perfusion blood volume CT, lung perfusion SPECT and catheter pulmonary angiography images in patients with chronic thromboembolic pulmonary hypertension before and after balloon pulmonary angioplasty

OBJECTIVES

Lung perfusion blood volume (PBV) using dual-energy computed tomography has recently become an accepted technique for diagnosing pulmonary thromboembolism. We evaluated the correlation among lung PBV, single-photon emission computed tomography (SPECT) and catheter pulmonary angiography images in patients with chronic thromboembolic pulmonary hypertension (CTEPH) before and after balloon pulmonary angioplasty (BPA).

METHODS

In total, 17 patients and 57 sessions were evaluated with the three modalities. Segmental lung perfusion and its improvement in lung PBV and SPECT were compared with catheter pulmonary angiography as the reference standard before and after BPA.

RESULTS

The sensitivity for detecting segmental perfusion defects using SPECT and lung PBV was 85% and 92%, the specificity was 99% and 99%, the accuracy was 92% and 95%, the positive predictive value was 99% and 99%, and the negative predictive value was 88% and 93%. The sensitivity for detecting segmental perfusion improvement using SPECT and lung PBV was 61% and 69%, the specificity was 75% and 83%, the accuracy was 62% and 70%, the positive predictive value was 97% and 98%, and the negative predictive value was 12% and 16%.

CONCLUSIONS

Lung PBV is a useful technique for evaluation of segmental lung perfusion and its improvement in patients with CTEPH.

KEY POINTS

• BPA is a new treatment for patients with CTEPH. • Lung PBV images may be more sensitive for pulmonary blood flow. • The current work demonstrates that Lung PBV images are useful in evaluating patients with CTEPH. • The current work demonstrates that Lung PBV is useful in gauging the treatment effect of BPA.