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.

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.

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.

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.

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.

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.

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.

Multidetector computed tomography for acute pulmonary embolism.

BACKGROUND: The accuracy of multidetector computed tomographic angiography (CTA) for the diagnosis of acute pulmonary embolism has not been determined conclusively. METHODS: The Prospective Investigation of Pulmonary Embolism Diagnosis II trial was a prospective, multicenter investigation of the accuracy of multidetector CTA alone and combined with venous-phase imaging (CTA-CTV) for the diagnosis of acute pulmonary embolism. We used a composite reference test to confirm or rule out the diagnosis of pulmonary embolism. RESULTS: Among 824 patients with a reference diagnosis and a completed CT study, CTA was inconclusive in 51 because of poor image quality. Excluding such inconclusive studies, the sensitivity of CTA was 83 percent and the specificity was 96 percent. Positive predictive values were 96 percent with a concordantly high or low probability on clinical assessment, 92 percent with an intermediate probability on clinical assessment, and nondiagnostic if clinical probability was discordant. CTA-CTV was inconclusive in 87 of 824 patients because the image quality of either CTA or CTV was poor. The sensitivity of CTA-CTV for pulmonary embolism was 90 percent, and specificity was 95 percent. CTA-CTV was also nondiagnostic with a discordant clinical probability. CONCLUSIONS: In patients with suspected pulmonary embolism, multidetector CTA-CTV has a higher diagnostic sensitivity than does CTA alone, with similar specificity. The predictive value of either CTA or CTA-CTV is high with a concordant clinical assessment, but additional testing is necessary when the clinical probability is inconsistent with the imaging results.

Reconstructed 4-chamber views compared with axial imaging for assessment of right ventricular enlargement on CT pulmonary angiograms.

PURPOSE: To test the hypothesis that right enlargement assessed from right ventricular/left ventricular (RV/LV) dimension ratios of computed tomographic (CT) angiograms are equivalent irrespective of whether measured on axial views or reconstructed 4-chamber views. METHODS: RV/LV dimension ratios were calculated from measurements on axial views, manually reconstructed 4-chamber views and computer generated reconstructed 4-chamber views of CT angiograms in 152 patients with PE. RESULTS: Paired readings of the axial view and manually reconstructed 4-chamber view showed agreement with RV/LV > or =1 or RV/LV <1 in 114 of 127 (89.8%). Paired readings also showed agreement in 119 of 127 (93.7%) with axial views and computer generated reconstructed 4-chamber views. The McNemar test showed no statistically significant difference between assessments of RV enlargement (RV/LV > or = 1) with any method. CONCLUSION: Right ventricular enlargement can be determined from axial views on CT angiograms, which are readily and immediately available, without obtaining 4-chamber reconstructed views.

Imaging of pulmonary thromboembolism.

Pulmonary thromboembolism usually results from deep venous thrombi originating in the lower extremities. Therefore, imaging of venous thromboembolism includes evaluation of the pulmonary arteries and the deep veins of the lower extremities. The introduction of helical CT and multidetector row CT into daily use has enabled direct visualization of pulmonary arteries. CT venography, performed 3 minutes after CT pulmonary angiography (without additional contrast administration), adds the ability to evaluate the veins of the lower extremities and pelvis. The modalities currently used in the diagnostic workup of venous thromboembolic disease and their advantages and disadvantages are discussed in this article.

Smoking-related interstitial lung disease.

Pulmonary diseases associated with tobacco smoking are a complex group of disorders ranging from chronic obstructive pulmonary disease (COPD) to lung cancer. Interstitial lung diseases (ILDs) have only recently been linked to smoking. The ILDs related to smoking include respiratory bronchiolitis-associated interstitial lung disease, desquamative interstitial pneumonia, and pulmonary Langerhans cell histiocytosis. The relationship of smoking with each of these entities has been largely established on the weight of epidemiologic evidence. Although they have been retained as distinct and separate conditions in various classifications of interstitial lung diseases, these 3 entities share a number of clinical, radiologic, and pathologic features suggesting that they represent a spectrum of patterns of interstitial lung disease occurring in predisposed individuals who smoke. Evaluation of histologic features, particularly in surgical lung biopsy samples, is important in making the distinction between these disorders. However, even after tissue biopsy, it may sometimes be difficult to clearly separate these entities. The importance of making the distinction between them lies in the different clinical management strategies used. Further experimental evidence, including genetic information, may be important in improving our understanding of these diseases.

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.

Usefulness of multidetector spiral computed tomography according to age and gender for diagnosis of acute pulmonary embolism.

Data from the Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) were evaluated to test the hypothesis that the performance of multidetector computed tomographic (CT) pulmonary angiography and CT venography is independent of a patient's age and gender. In 773 patients with adequate CT pulmonary angiography and 737 patients with adequate CT pulmonary angiography and CT venography, the sensitivity and specificity for pulmonary embolism for groups of patients aged 18 to 59, 60 to 79, and 80 to 99 years did not differ to a statistically significant extent, nor were there significant differences according to gender. Overall, however, the specificity of CT pulmonary angiography was somewhat greater in women, but in men and women, it was > or =93%. In conclusion, the results indicate that multidetector CT pulmonary angiography and CT pulmonary angiography and CT venography may be used with various diagnostic strategies in adults of all ages and both genders.

CT venography and compression sonography are diagnostically equivalent: data from PIOPED II.

OBJECTIVE: The purpose of this study was to compare the clinical value of CT venography (CTV) after MDCT angiography (CTA) with venous compression sonography for the diagnosis of venous thromboembolism (VTE). The Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) showed that lower extremity imaging detects about 7% more patients requiring anticoagulation than CTA alone. SUBJECTS AND METHODS: PIOPED II was a prospective multicenter study investigating the accuracy of CTA alone and CTA and CTV together. A composite reference standard was used to confirm, or rule out, pulmonary embolus. Adequate quality CTV and sonographic images were obtained in 711 patients. RESULTS: There was 95.5% concordance between CTV and sonography for the diagnosis or exclusion of deep venous thrombosis (DVT); the kappa statistic was 0.809. The sensitivity and specificity of combined CTA and CTV were equivalent to those of combined CTA and sonography. Diagnostic results in subgroups, including patients with signs or symptoms of DVT, asymptomatic patients, and patients with a history of DVT, were similar whether CTV or sonography was used. Patients with signs or symptoms of DVT were eight times more likely to have DVT, and patients with a history of DVT were twice as likely to have positive findings. CONCLUSION: CTV and sonography showed similar results in diagnosing or excluding DVT. The incidence of positive studies in patients without signs, symptoms, or history of DVT is low. In terms of clinical significance, CT venography and lower extremity sonography yield equivalent diagnostic results; the incidence of positive studies in patients without signs, symptoms, or history of DVT is low; thus the choice of imaging technique can be made on the basis of safety, expense, and time constraints.

CT venography for deep venous thrombosis: continuous images versus reformatted discontinuous images using PIOPED II data.

OBJECTIVE: This study was designed to determine whether discontinuous CT of the lower extremities for the detection of deep venous thrombosis (DVT) yields results similar to those of complete helical imaging using cases from the Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II). MATERIALS AND METHODS: In PIOPED II, CT venography followed CT angiography (CTA) to detect pulmonary embolus, using 7.5-mm continuous helical imaging from the iliac crest to the tibial plateau. DVT was detected in 105 of 737 patients (14.2%). We randomly chose 54 positive cases and 96 negative cases for our study. The continuous helical images were reformatted as 7.5-mm images and two of every three images were deleted. These images (7.5 mm; skip = 15 mm) were then sent--without identifying information--to the original reviewers. From 1 to 3.5 years had elapsed since the original interpretations. The results of the new interpretations were compared with the original CT venography consensus interpretations of PIOPED II. RESULTS: There was agreement for the presence of DVT in at least one leg (same leg) or for the absence of DVT in both legs in 133 of the 150 study patients (89%). The kappa statistic showed substantial agreement between the consensus interpretations and the test interpretations (kappa = 0.75; 95% CI = 0.64-0.86) per patient. CONCLUSION: There was good--but not perfect--agreement between continuous helical and discontinuous axial imaging for the detection of DVT. Given the vagaries of interobserver and intraobserver variation, there appears to be little difference between the two approaches. Adopting discontinuous imaging and other dose-reduction strategies can reduce pelvic radiation by more than 75%.