Mosaic attenuation pattern (pulmonary hypertension)

Case contributed by Melbourne Uni Radiology Masters


ESRF on a background of longstanding polycystic renal abnormality. V/Q scan shows evidence of current PE. Past history of multiple PE.

Patient Data

Age: 45
Gender: Female


Both lungs demonstrate multiple regions of mosaic attenuation, most prominent in both lower lobes. This is associated with enlargement of the central pulmonary arteries, with the pulmonary trunk measuring up to 3.7cm in maximum transverse diameter. There is cardiomegaly with significant right heart enlargement. No pericardial effusion. No pleural effusion.

Bibasal atelectasis. No pulmonary nodules. No evidence of bronchiectasis or interstitial lung disease.

Numerous mildly enlarged mediastinal lymph nodes are demonstrated, with an aortopulmonary node measuring up to 18.5 x 11.5 mm. Hilar lymph nodes are difficult to evaluate on this non-contrast study. No axillary or retrocrural lymphadenopathy.

Beneath the hemidiaphragm, multiple low attenuation liver lesions are seen, as noted previously, in keeping with multiple hepatic cysts. A coarse focus of calcification in association with one of the cysts in the superior right lobe measuring 6.6mm has increased in size but has a benign appearance.

A gastric Lap band is in situ.

No suspicious bony lesion.

Conclusion: Enlargement of the pulmonary arterial tree with cardiomegaly and right heart enlargement. Mosaic attenuation in both lungs is likely due to pulmonary hypertension, rather than a pulmonary parenchymal disease.

Case Discussion

The CT shows areas of mosaic attenuation with a considerably dilated central pulmonary artery in keeping with changes of pulmonary arterial hypertension, probably on a background of recurrent PE.

No expiratory study was performed, the airways appear normal with no features to suggest an obliterative or constrictive bronchiolitis abnormality.

The mosaic pattern is suspicion of changes resulting from severe pulmonary arterial hypertension.

Mosaic attenuation is a non-specific finding, which may be seen in any of the following:

  • obstructive small airways disease: low attenuation regions are abnormal and reflect decreased perfusion of the poorly ventilated regions, e.g. bronchiectasis, cystic fibrosis, constrictive bronchiolitis
  • occlusive vascular disease (can be termed a mosaic perfusion pattern in this setting 7): low attenuation regions are abnormal and reflect relative oligaemia, e.g. chronic pulmonary embolism
  • parenchymal disease: high attenuation regions are abnormal and represent ground-glass opacity


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Case information

rID: 43961
Published: 6th May 2016
Last edited: 26th Sep 2017
System: Chest
Tag: rmh
Inclusion in quiz mode: Excluded

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