Pugliese, Steven C.

Purpose: To measure the computed tomography (CT) attenuation of acute pulmonary embolism (PE) and establish an upper Hounsfield unit (HU) threshold above which it is unlikely to occur. Materials and Methods: This retrospective study analyzed CT pulmonary angiography (CTPA) exams in patients with acute PE (2018–2023) who had a prior negative CTPA in the preceding 2 weeks. Clot and artifact attenuation were measured on the positive and prior negative CTPA respectively. Analysis of variance with post hoc tests and linear regression analysis were performed to determine the effects of technical and other parameters on clot and artifact attenuation. Results: A total of 60 patients were included, each with 1 record or a pair of CTPA exams, yielding 105 clots and 41 artifacts. Mean attenuation for acute PE was 50±40 HU, and for artifact was 110±146 HU. A threshold of 125 HU achieved 97% (102/105) sensitivity for acute PE below it and the same specificity for artifact above it. Specificity for acute PE below this threshold was 37% (15/41). Subsegmental clots had a lower attenuation than all other clots as a group. Kilovoltage peak (kVp) and proximal vessel attenuation were poor predictors of clot attenuation . Conclusions: Most acute PE demonstrated a CT attenuation ≤125 HU on standard CTPA, an upper threshold higher than previously reported, while artifacts demonstrated both lower and higher attenuation. An attenuation >125 HU on standard CTPA, favoring artifact rather than acute PE, may be a useful adjunct to morphologic differentiation between these entities.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, morbid, potentially curable subtype of pulmonary hypertension that negatively impacts health‐related quality of life (HRQoL). Little is known about differences in HRQoL and hospitalization between CTEPH patients and idiopathic pulmonary arterial hypertension (IPAH) patients. Using multivariable linear regression and mixed effects models, we examined differences in HRQoL assessed by emPHasis‐10 (E10) and SF‐12 between CTEPH and IPAH patients in the Pulmonary Hypertension Association Registry, a prospective multicenter cohort of patients newly evaluated at a Pulmonary Hypertension Care Center. Multivariable negative binomial regression models were used to estimate incidence rate ratios (IRR) for hospitalization amongst the two groups. We included 461 IPAH patients and 169 CTEPH patients. Twenty‐one percent of CTEPH patients underwent pulmonary thromboendarterectomy (PTE) before the end of follow‐up. At baseline, patients with CTEPH had significantly worse HRQoL (higher E10 scores) (ß 2.83, SE 1.11, p = 0.01); however, differences did not persist over time. CTEPH patients had higher rates of hospitalization (excluding the hospitalization for PTE) compared to IPAH patients after adjusting for age, sex, body mass index, WHO functional class and six‐minute walk distance (IRR 1.66, 95%CI 1.04–2.65, p = 0.03). CTEPH patients who underwent PTE had improved HRQoL as compared to those who were medically managed, but patients who underwent PTE were younger, had higher cardiac outputs and greater six‐minute walk distances. In this large, prospective, multicenter cohort, CTEPH patients had significantly worse baseline HRQoL and higher rates of hospitalizations than those with IPAH. CTEPH patients who underwent PTE had significant improvements in HRQoL.