Assessment of cross-sectional lung ventilation-perfusion imbalance in primary and passive pulmonary hypertension with automated V/Q SPECT.
OBJECTIVE
Cross-sectional lung ventilation (V)-perfusion (Q) imbalance in primary pulmonary arterial hypertension (PAH) and passive pulmonary hypertension (PH) was characterized by automated V/Q single-photon emission computed tomography (SPECT).


METHODS
Technegas/macro-aggregated albumin SPECT-derived V/Q SPECT and V/Q profile were automatically built to characterize cross-sectional lung V-Q imbalance in 12 patients with primary (idiopathic or familial) PAH and 15 patients with passive PH associated with left ventricular dysfunction or failure. The abnormality of V/Q distribution in these patients was correlated with PaO2 and pulmonary arterial pressure and with lung morphologic changes on computed tomography (CT).


RESULTS
Markedly low V/Q ratios (reverse V-Q mismatch) in the background lungs with heterogeneous V/Q distribution was seen in 12 of the 12 (100%) patients with primary PAH and in 10 of the 15 (66%) patients with passive PH, which were predominantly seen in the upper lung zone. Including these regions with reverse V-Q mismatch, the V/Q profile frequently showed flattened peaks with asymmetric and broadened V/Q distribution in all patients, with significant correlation between the standard deviation of V/Q ratios in the entire lungs and PaO2 and mean pulmonary arterial pressure (both; P<0.01). At the regions of the lungs with reverse V-Q mismatch, bronchial lumens compressed by dilated pulmonary arteries and heterogeneous lung attenuations were frequently seen on CT.


CONCLUSIONS
Patients with primary PAH and passive PH seem to characteristically have a high prevalence of reverse V-Q mismatch indicative of an inadequate hypoxic vasoconstriction reflex on V/Q SPECT, frequently accompanied with heterogeneous lung attenuations and compressed airways on CT.
Suga
Kazuyoshi
K
Department of Radiology, St Hill Hospital, Yamaguchi, Japan. sugar@sthill-hp.or.jp
Tokuda
Osamu
O
Okada
Munemasa
M
Koike
Masahiro
M
Iwanaga
Hideyuki
H
Matsunaga
Naofumi
N
D000328:Adult; D000368:Aged; D000418:Albumins; D001331:Automation; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008168:Lung / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D013670:Sodium Pertechnetate Tc 99m; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio; D055815:Young Adult
D000418:Albumins; C056708:Technegas; D013670:Sodium Pertechnetate Tc 99m