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.

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.

Pulmonary vein thrombosis in patients with medical risk factors.

Pulmonary vein thrombosis in patients with medical illnesses has been rarely reported, and it is also rarely reported in those with no risk factors. We report 2 patients with pulmonary vein thrombosis, 1 with metastatic renal cell carcinoma and 1 with presumed pulmonary aspergillosis. Thrombi or tumors in a pulmonary vein are clinically important because they may cause systemic embolism or hemoptysis.

Reduced z-axis technique for CT Pulmonary angiography in pregnancy--validation for practical use and dose reduction.

The aim of this study is to determine the feasibility of using reduced scan range CT pulmonary angiography technique in pregnancy for pulmonary embolism (PE) and to quantify resulting dose reduction. This was a retrospective study. Eighty-four CTPA exams performed on pregnant women during 2004-2012. The scans were modified to create reduced anatomic coverage scans extending from aortic arch to base of heart. These were separately evaluated by two radiologists for PE and non-PE abnormalities. The results were then compared by the third radiologist with original radiology report and scans. Radiation dose reduction was evaluated prospectively in 36 patients as part of a quality control project. Two patients had PE and were successfully identified on reduced z-axis scans. Thirty-two exams were normal; rest had 60 pertinent and 16 had incidental findings. There were four incidental findings which included three benign thyroid nodules and one benign small lung nodule which were missed. None of these affected clinical outcome or management. There was 71 % radiation dose reduction. No PE or any important diagnoses are missed using reduced z-axis CTPA in pregnancy. There is a substantial radiation dose reduction. Hence, this technique is highly recommended in pregnancy.

The azygos vein pathway: an overview from anatomical variations to pathological changes.

The azygos venous system represents an accessory venous pathway supplying an important collateral circulation between the superior and inferior vena cava. The aim of this article is to revise the wide spectrum of changes ranging from normal to pathological conditions involving the azygos system. Teaching points • The azygos vein is a collateral venous pathway, becoming a vital shunt if major pathways of venous return are obstructed. • In azygos continuation, the azygos vein becomes significantly enlarged due to inferior vena cava interruption. • Fibrosing mediastinitis is an underestimated acquired disorder. • Fibrosing mediastinitis induces a variable engorgement of collateral veins. • Fibrosing mediastinitis leads to superior vena cava syndrome.

In search of venous thromboembolism: the first 2913 years.

OBJECTIVE: Venous thromboembolism was first described in India around 600-900 BC. It was not until the 17th through 19th centuries that Western researchers began to understand the anatomy, physiology, and pathology of deep venous thrombosis and pulmonary embolism. Roentgen's discovery of x-rays in 1895 led to the first objective imaging. CONCLUSION: Currently, scintigraphy, helical CT, MRI, and sonography provide accurate in vivo images. These high-quality images have forced clinicians to reevaluate many preimaging assumptions about and treatments for venous thromboembolism.

Dose reduction of 69% for computed tomography pulmonary angiography: reduced z-axis computed tomography pulmonary angiography retains accuracy in those younger than 40 years.

OBJECTIVE: We sought to determine whether reduced scan range (z axis) computed tomography pulmonary angiography (CTPA) technique in 18- to 40-year age group can accurately detect pulmonary embolism (PE) and other important conditions and to quantify the resulting dose reduction. METHODS: We retrospectively identified 200 patients in the age group of 18 to 40 years who underwent CTPA over a period of 3 years. These included 86 patients with PEs and 114 randomly selected patients negative for PE (control subjects). The scans were modified by reducing the scan coverage by eliminating images above the aortic arch and below the base of the heart. Two blinded experienced radiologists rescored them for PE and incidental and pertinent non-PE findings. Discrepancies between these and the original report were assessed by a third experienced radiologist. Separately, a departmental quality-control project was conducted in 15 patients to assess the dose length product along the z axis across the 3 zones of thorax. RESULTS: Pulmonary embolism was diagnosed in all 86 patients. No pertinent additional findings were missed. Only 7 incidental findings were missed (eg, benign thyroid nodules [n = 4], benign adrenal adenoma [n = 1], gallstones [n = 1], and hepatic hemangioma [n = 1]). None affected clinical outcome or management. Dose length product was reduced by a mean of 69% (60%-79%). CONCLUSIONS: Reduced z-axis CTPA for PE is definitely feasible in 18- to 40-year age group. There is a significant radiation reduction (69%) and hence should be considered in selected subgroups of patients.

Use of combination chemotherapy for treatment of granulomatous and lymphocytic interstitial lung disease (GLILD) in patients with common variable immunodeficiency (CVID).

PURPOSE: A subset of patients with common variable immunodeficiency (CVID) develops granulomatous and lymphocytic interstitial lung disease (GLILD), a restrictive lung disease associated with early mortality. The optimal therapy for GLILD is unknown. This study was undertaken to see if rituximab and azathioprine (combination chemotherapy) would improve pulmonary function and/or radiographic abnormalities in patients with CVID and GLILD. METHODS: A retrospective chart review of patients with CVID and GLILD who were treated with combination chemotherapy was performed. Complete pulmonary function tests (PFTs) and high-resolution computed tomography (HRCT) scans of the chest were done prior to therapy and >6 months later. HRCT scans of the chest were blinded, randomized, and scored independently (in pairs) by two radiologists. The differences between pre- and post-treatment HRCT scores and PFT parameters were analyzed. RESULTS: Seven patients with CVID and GLILD met inclusion criteria. Post-treatment increases were noted in both FEV1 (p=0.034) and FVC (p=0.043). HRCT scans of the chest demonstrated improvement in total score (p=0.018), pulmonary consolidations (p=0.041), ground-glass opacities (p=0.020) nodular opacities (p=0.024), and both the presence and extent of bronchial wall thickening (p=0.014, 0.026 respectively). No significant chemotherapy-related complications occurred. CONCLUSIONS: Combination chemotherapy improved pulmonary function and decreased radiographic abnormalities in patients with CVID and GLILD.

Power injectable peripherally inserted central venous catheter lines frequently flip after power injection of contrast.

OBJECTIVE: To determine the frequency of power injectable peripherally inserted central venous catheter (PIPICC) displacement after contrast injection for computed tomography. MATERIALS AND METHODS: We included all patients who had a computed tomographic examination with contrast administration via PIPICC over a 4-month period. Several variables including catheter location before and after the injection were documented. Descriptive statistics were used for continuous variables. The χ² test was used to compare groups. Continuous variables were analyzed using the Student t test. RESULTS: Among 78 injections in 67 patients (34 men and 33 women; median age, 49 years), there were 12 catheter displacements (15.4%): 5 (62.5%) of 8 catheters initially located proximal to the tracheobronquial angle (TBA) and 7 (10.14%) of 69 catheters initially located distal to the TBA. The initial catheter position before the injection correlated with the frequency of displacement significantly (P < 0.006). Contrast injection rate and amount of contrast were no risk factors for position change. There were no complications. CONCLUSION: Catheter displacement occurred in 62.5%, with PIPICCS cephalad to the TBA. A preliminary scout view should be checked before the contrast injection. In addition, a postinjection scan scout view is recommended to verify catheter position.

Diagnosis and management of isolated subsegmental pulmonary embolism: review and assessment of the options.

We assessed the potential safety of withholding treatment of pulmonary embolism (PE) limited to subsegmental branches. Literature review showed that untreated patients with mostly subsegmental PE had no fatal recurrences in 1 to 3 months and no nonfatal recurrences of PE in 3 months. Patients with suspected PE who had nondiagnostic ventilation/perfusion lung scans, adequate cardiorespiratory reserve or low or moderate clinical probability, and negative serial noninvasive leg tests were shown not to require treatment. It appears safe, therefore, to withhold treatment of subsegmental PE providing (1) pulmonary-respiratory reserve is good; (2) no evidence of deep venous thrombosis (DVT) on serial testing; (3) major risk factor for PE was transient and no longer present; (4) no history of central venous catheterization or atrial fibrillation; and (5) willingness to return for serial venous ultrasound. After fully informing patients, some may choose to be treated and some may choose not to be treated.

Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose gadopentetate dimeglumine.

During a recent multi-center trial assessing gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE), the Food and Drug Administration announced a risk of nephrogenic sclerosing fibrosis in patients with renal insufficiency who had received intravenous Gd-based MR contrast agents. Although no patients in this trial had renal insufficiency, in cautious response to this announcement, the trial protocol was changed from an intravenous administration of 0.2 mmol/Kg of a conventional Gd-based MR contrast agent to 0.1 mmol/Kg of gadobenate dimeglumine. The study described herein compares the signal quality of pulmonary MRA performed with double dose conventional agent to single dose gadobenate dimeglumine. This study is a retrospective analysis of data from a prospective, multicenter study in men and women ≥18 years with documented presence or absence of PE. The study was approved by the Institutional Review Board at all participating centers, and all patients provided written indication of informed consent. We performed both objective and subjective analysis of pulmonary artery image quality. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the main pulmonary artery were assessed in single and double dose protocols and compared. SNR and CNR of the main PA were correlated with subjective quality assessment of main/lobar, segmental and subsegmental pulmonary arteries. Although there were individual outliers, both SNR (P = 0.01) and CNR (P = 0.008) were higher in all quartiles for examinations using gadobenate dimeglumine than with gadopentetate dimeglumine. Subjective quality of vascular signal intensity at each vessel order was significantly better for gadobenate dimeglumine (P < 0.0001), and correlated well with SNR and CNR at each order (<0.001). Because of agent high relaxivity, a single dose of gadobenate dimeglumine provides better pulmonary MRA signal quality than double dose of a conventional Gd-based MR contrast agent.

Factors in the technical quality of gadolinium enhanced magnetic resonance angiography for pulmonary embolism in PIOPED III.

In a multi-center trial, gadolinium enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE) had a high rate of technically inadequate images. Accordingly, we evaluated the reasons for poor quality MRA of the pulmonary arteries in these patients. We performed a retrospective analysis of the data collected in the PIOPED III study. We assessed the relationship to the proportion of examinations deemed "uninterpretable" by central readers to the clinical centers, MR equipment platform and vendors, degree of vascular opacification in different orders of pulmonary arteries; type, frequency and severity of image artifacts; patient co-morbidities, symptoms and signs; and reader characteristics. Centers, MR equipment vendor and platform, degree of vascular opacification, and motion artifacts influenced the likelihood of central reader determinations that images were "uninterpretable". Neither the reader nor patient characteristics (age, body mass index, respiratory rate, heart rate) correlated with the likelihood of determining examinations "uninterpretable". Vascular opacification and motion artifact are the principal factors influencing MRA interpretability. Some centers obtain better images more consistently, but the reasons for differences between centers are unclear.

Controversies in diagnosis of pulmonary embolism.

The approach to the diagnosis of acute pulmonary embolism (PE) is under constant revision with advances in technology, noninvasive approaches, and increasing awareness of the risks of ionizing radiation. Optimal approaches in some categories of patients are controversial. Data are insufficient for evidence-based recommendations. Therefore, this survey of investigators in the field was undertaken. Even among experts there were marked differences of opinion regarding the approach to the diagnosis of acute PE. Although CT pulmonary angiography was usually the imaging test of choice, the respondents were keenly aware of the dangers of ionizing radiation. In view of advances in scintigraphic diagnosis since the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) trial, ventilation/perfusion (V/Q) lung scans or perfusion scans alone and single photon emission computed tomography (SPECT) V/Q lung scans are often recommended. The choice depends on the patient's age, gender, and complexity of the findings on the plain chest radiograph.

Pulmonary embolism: optimizing the diagnostic imaging approach.

Venous thromboembolism is a common medical problem that can affect a wide range of patients. The clinical presentation ranges from minor, nonspecific signs and symptoms to severe clinical scenarios. The combination of objective pretest clinical probability, D-dimer testing, and imaging studies plays a critical role in its diagnosis. There are multiple imaging modalities to confirm or exclude the presence of pulmonary embolism and deep vein thrombosis, but, at present, computed tomography angiography is the most frequently used. Other imaging, however, is required for several subpopulations.

Pulmonary embolism in pregnancy: CT pulmonary angiography versus perfusion scanning.

OBJECTIVE: The purpose of this study was to evaluate the equivalence of CT pulmonary angiography and perfusion scanning in terms of diagnostic quality and negative predictive value in the imaging of pulmonary embolism (PE) in pregnancy. MATERIALS AND METHODS: Between 2000 and 2007 at a university hospital and a large private hospital, 199 pregnant patients underwent 106 CT pulmonary angiographic examinations and 99 perfusion scans. Image quality was evaluated, and the findings were reread by radiologists and compared with the original clinical readings. Three-month follow-up findings of PE and deep venous thrombosis were recorded. RESULTS: PE was found in four of the 106 patients (3.7%) who underwent CT pulmonary angiography. The overall image quality was poor in 5.6% of cases, acceptable in 17.9%, and good in 76.4%. Fourteen CT and nine radiographic studies showed other clinically significant abnormalities. Six patients had indeterminate CT pulmonary angiographic findings, three had normal perfusion scans, and none underwent anticoagulation. All perfusion scan findings were normal. There was one incomplete study, and follow-up CT pulmonary angiography performed the same day showed PE. Two of 99 studies (2.02%) showed intermediate probability of the presence of PE; PE was not found at CT pulmonary angiography, but pneumonia was found. PE was found in one postpartum patient 9 weeks after she had undergone CT pulmonary angiography and ultrasound with normal findings. None of the patients died. CONCLUSION: CT pulmonary angiography and perfusion scanning have equivalent clinical negative predictive value (99% for CT pulmonary angiography; 100% for perfusion scanning) and image quality in the care of pregnant patients. Therefore, the choice of study should be based on other considerations, such as radiation concern, radiographic results, alternative diagnosis, and equipment availability. Reducing the amount of radiation to the maternal breast favors use of perfusion scanning when the radiographic findings are normal and there is no clinical suspicion of an alternative diagnosis.

Resolution of pulmonary embolism on CT pulmonary angiography.

OBJECTIVE: The objective of our study was to retrospectively determine the rate of resolution of pulmonary emboli (PEs) in individual vessels and the rate of complete resolution of PEs on CT angiography. MATERIALS AND METHODS: Follow-up CT pulmonary angiograms, obtained during the period from January 2006 through May 2009, of 69 patients with acute PE from two hospitals were assessed. Initial and follow-up CT angiograms were reread together by one radiologist at both of the hospitals. Images were obtained using a 10-, 16-, 40-, or 64-MDCT angiography unit with a 0.5-mm collimation, 1.25- to 2.0-mm reconstruction, 0.3- to 0.5-second rotation time, and 7.5-mm/rotation table speed. All CT angiograms were obtained using a PE protocol. RESULTS: Follow-up CT angiograms were obtained in 35 men and 34 women who ranged in age from 17 to 92 years (mean age, 58 +/- 17 [SD] years). Complete CT angiographic resolution of PE was seen in six of 15 patients (40%) 2-7 days after diagnostic imaging. After day 28, complete resolution occurred in 17 of 21 patients (81%). The main pulmonary arteries showed complete PE resolution during days 2-7 in seven of nine patients (78%) and after day 28 in 34 of 36 (94%). The lobar pulmonary arteries showed complete resolution of PE during days 2-7 in 23 of 33 patients (70%) and after 28 days in 44 of 48 (92%). The segmental pulmonary arteries showed complete resolution during days 2-7 in eight of 21 patients (38%) and after day 28 in 38 of 38 (100%). CONCLUSION: Most patients (81%) showed complete resolution of PE on CT angiography after 28 days. PEs resolved faster in the main and lobar pulmonary arteries than in the segmental branches.

The Beatles, the Nobel Prize, and CT scanning of the chest.

Chest CT scanning has come a long way since 1975. Anatomic images are now superb and functional imaging is in its early stages.

Gadolinium-enhanced magnetic resonance angiography for pulmonary embolism: a multicenter prospective study (PIOPED III).

BACKGROUND: The accuracy of gadolinium-enhanced magnetic resonance pulmonary angiography and magnetic resonance venography for diagnosing pulmonary embolism has not been determined conclusively. OBJECTIVE: To investigate performance characteristics of magnetic resonance angiography, with or without magnetic resonance venography, for diagnosing pulmonary embolism. DESIGN: Prospective, multicenter study from 10 April 2006 to 30 September 2008. SETTING: 7 hospitals and their emergency services. PATIENTS: 371 adults with diagnosed or excluded pulmonary embolism. MEASUREMENTS: Sensitivity, specificity, and likelihood ratios were measured by comparing independently read magnetic resonance imaging with the reference standard for diagnosing pulmonary embolism. Reference standard diagnosis or exclusion was made by using various tests, including computed tomographic angiography and venography, ventilation-perfusion lung scan, venous ultrasonography, d-dimer assay, and clinical assessment. RESULTS: Magnetic resonance angiography, averaged across centers, was technically inadequate in 25% of patients (92 of 371). The proportion of technically inadequate images ranged from 11% to 52% at various centers. Including patients with technically inadequate images, magnetic resonance angiography identified 57% (59 of 104) with pulmonary embolism. Technically adequate magnetic resonance angiography had a sensitivity of 78% and a specificity of 99%. Technically adequate magnetic resonance angiography and venography had a sensitivity of 92% and a specificity of 96%, but 52% of patients (194 of 370) had technically inadequate results. LIMITATION: A high proportion of patients with suspected embolism was not eligible or declined to participate. CONCLUSION: Magnetic resonance pulmonary angiography should be considered only at centers that routinely perform it well and only for patients for whom standard tests are contraindicated. Magnetic resonance pulmonary angiography and magnetic resonance venography combined have a higher sensitivity than magnetic resonance pulmonary angiography alone in patients with technically adequate images, but it is more difficult to obtain technically adequate images with the 2 procedures.