Septic Pulmonary Emboli

 

CT Finding	Septic Pulmonary Emboli (SPE)	Hematogenous Metastases	Angio-invasive Fungal	Granulomatosis with Polyangiitis	Bland PE / Infarct
Typical distribution	Multiple bilateral peripheral nodules	Random; no pleural predilection	Peribronchovascular & random	Diffuse upper/lowero lbes	Wedge-shaped pleural-based opacity
Feeding-vessel sign	Common (≈60-80%)	Uncommon	Rare	Absent	Enlarged occluded artery (different appearance)
Cavitation	Frequent; thick-walled	Occasional; thin-walled	Very common → air-crescent sign	Common; irregular	Uncommon (late “gangrene”)
Halo sign	Possible	Rare	Classic early sign	May be present	Reverse-halo may evolve
Air-fluid level in nodule	Supports SPE	Rare	Possible (advanced)	Possible	Rare
Tree-in-bud pattern	Common	Rare	Possible	Possible	Absent
Pleural effusion / empyema	Up to 30 %; may be loculated	Rare	Possible	Occasional	Small effusion common
Vascular / cardiac clues	Central line, right-heart clot, septic thrombus	None	None	None	Pulmonary artery filling defect
Clinical context	Bacteremia, R-sided endocarditis, infected device	Known malignancy	Neutropenia, transplant, steroids	ENT/kidney disease, c-ANCA +	Recent DVT/PE, hypercoagulable
Evolution on follow-up CT	Rapid change ⇢ resolves on antibiotics	Slow response to oncologic Rx	Rapid progression if untreated	Slow improvement with immunosuppression	Opacity scars over weeks

How to Use This Table

• Step 1 — Scan for a feeding-vessel sign: a vessel entering a cavitating peripheral nodule strongly tips the balance toward SPE.
• Step 2 — Check distribution & ancillary signs: tree-in-bud plus cavitating nodules along the pleura + bacteremia = think SPE. A solitary wedge opacity without nodules leans toward bland infarct.
• Step 3 — Integrate clinical data: positive blood cultures or a known infected line shifts probability sharply toward SPE; a neutropenic host raises fungal concern; known cancer favors metastases.
• Step 4 — Plan targeted work-up: if SPE suspected, obtain blood cultures, transthoracic/TEE echo, and search for thrombophlebitis or infected devices while starting broad-spectrum antibiotics.

The pattern of multiple bilateral, predominantly peripheral nodules—several with central cavitation and a visible “feeding-vessel” sign—fits best with septic pulmonary emboli (often secondary to right-sided endocarditis, infected intravascular devices, or other deep sources of bacteremia). Other differentials (fungal nodules, vasculitis, hematogenous metastases) are possible, but the morphology and distribution here most strongly favor septic emboli.