Table 1.
Baseline characteristics.
Fig 1.
A 58-year-old man with an immunoglobulin G4-associated inflammatory abdominal aortic aneurysm (Ormond disease), initially presented with back pain and fever.
PET/CT (A: maximum intensity projection of PET; B: fused PET/CT images; C: native CT images) and contrast-enhanced CT (CE-CT: D) showed a 64 mm large abdominal aortic aneurysm (white arrows in A-D) with intense FDG uptake (SUVmax 9.0 in A and B) in the thickened (12 mm) aortic wall (white arrows in B-D) with prominent dorsal sparing. Using PET/CT images alone one reader correctly diagnosed an inflammatory aneurysm, while the other one falsely diagnosed an infectious/mycotic aneurysm. With CE-CT and with combined imaging both readers correctly diagnosed an inflammatory aneurysm. The patient was subsequently treated with percutaneous endovascular abdominal aortic aneurysm repair and steroid therapy. The latest follow-up imaging 2.5 years after the initial diagnosis (not shown), showed a smaller (42 mm) aneurysm with less FDG uptake (SUVmax 4.1); and the patient had no symptoms.
Fig 2.
A 42-year-old man with chronic periaortitis, initially presenting with left-sided abdominal pain.
PET/CT (A: maximum intensity projection of PET; B and C: fused PET/CT images (B) and contrast-enhanced CT (CE-CT: E) showed a 32 mm large abdominal aortic aneurysm (white arrows in B, C and E) with increased FDG uptake (SUVmax 3.5 in A-C) in the thickened (10 mm) aortic wall (white arrow in E). Using PET/CT images alone (A-D) both readers suspected an infectious/mycotic aneurysm (notably, wall thickening may not be clearly delineated on the non-enhanced CT part of the PET/CT in D, but only on the CE-CT in E). With CE-CT (E) and with combined imaging (not shown) both readers correctly diagnosed an inflammatory aneurysm. The patient was subsequently treated with steroid therapy for four months and no vascular intervention was performed. The latest follow-up imaging eight years after the initial diagnosis (not shown), showed no residual wall thickening in the normal sized (18 mm) abdominal aorta and the patient had no abdominal symptoms.
Fig 3.
A 51-year-old man with an inflammatory abdominal aortic aneurysm, initially presenting with back pain and abdominal pain.
PET/CT (A: maximum intensity projection of PET; B and E: fused PET/CT images) and contrast-enhanced CT (CE-CT: D) showed a 52 mm large abdominal aortic aneurysm (white arrows in B and D) with increased FDG uptake (SUVmax 3.6 in A and B) in the thickened (12 mm) aortic wall (white arrow in D) with dorsal sparing. Using PET/CT images alone (A-C) one reader correctly diagnosed an inflammatory aneurysm, while the other one falsely diagnosed an infectious/mycotic aneurysm (notably, wall thickening may not be clearly delineated on the non-enhanced CT part of the PET/CT in C, but only on the CE-CT in D). With CE-CT (E) and with combined imaging (not shown) both readers correctly diagnosed an inflammatory aneurysm. As an incidental finding, a small metabolically active pneumonia was diagnosed on PET/CT images (E). The patient was subsequently treated with percutaneous endovascular abdominal aortic aneurysm repair and steroid therapy. The latest follow-up imaging five years after the initial diagnosis (not shown), showed a stable abdominal aortic graft with no relevant wall thickening, and the patient had no abdominal symptoms.
Fig 4.
A 48-year-old man with a non-infected, non-inflammatory abdominal aortic aneurysm, initially diagnosed as an incidental finding on abdominal ultrasound.
PET/CT (A: maximum intensity projection of PET; B: fused PET/CT images (B); C native CT images) and contrast-enhanced CT (CE-CT: D) showed a 55 mm large abdominal aortic aneurysm (white arrows in B and D) with increased FDG uptake (SUVmax 5.2, black arrow in A, white arrow in B) in the thickened (20 mm) aortic wall (white arrow in D). Both readers rated all imaging data set falsely: using PET/CT images and CE-CT images alone, one reader diagnosed a mycotic/infectious aneurysm while the other one diagnosed an inflammatory aneurysm; both readers suspected an inflammatory aneurysm on combined imaging. The patient was subsequently treated with percutaneous endovascular abdominal aortic aneurysm repair and neither antibiotic nor steroid therapy. The latest follow-up imaging four years after the initial diagnosis, showed no residual wall thickening abdominal aorta (E) and the patient had no abdominal symptoms.
Fig 5.
A 52-year-old man with an infectious/mycotic abdominal aortic aneurysm caused by Streptococcus pneumoniae, initially presented with abdominal discomfort and elevated C-reactive protein levels.
PET/CT (A: maximum intensity projection of PET; B: fused PET/CT images; C native CT images) and contrast-enhanced CT (CE-CT: D) showed a 49 mm large abdominal aortic aneurysm (white arrows in B and D) with increased FDG-uptake (SUVmax 4.2; black arrow in A, white arrow in B) in the thickened (12 mm) aortic wall (white arrow in D). With all imaging data sets one reader correctly diagnosed an infectious/mycotic aneurysm, while the other one falsely diagnosed an inflammatory aneurysm on all imaging data sets. The patient was subsequently treated with endovascular aortic repair and antibiotic therapy.
Table 2.
Diagnostic accuracy of PET/CT, CE-CT, combined CE-PET/CT for diagnosis of MAA, IAA and AAA—combined for both readers, and Kappa statistics of the interrater agreement.
Table 3.
Relevance of imaging characteristics in PET/CT and CE-CT for diagnosis of MAA, IAA and AAA—combined for both readers.