J A C C : C A R D I O V A S C U L A R I M A G I N G V O L . - , N O . - , 2 0 1 7

ª 2 0 1 7 B Y T H E AM E R I C A N C O L L E G E O F C A R D I O L O G Y F O U N D A T I O N

P U B L I S H E D B Y E L S E V I E R

I S S N 1 9 3 6 - 8 7 8 X / $ 3 6 . 0 0

h t t p s : / / d o i . o r g / 1 0 . 1 0 1 6 / j . j c m g . 2 0 1 7 . 0 7 . 0 1 8

IMAGING VIGNETTE

Additional Diagnostic Value of CombinedAngio-Computed Tomography andFluorodeoxyglucose F-18 PositronEmission Tomography in Infectious Aortitis

Nidaa Mikail, MD,a,b Khadija Benali, MD,a,b Antoine Dossier, MD,c,d Claire Bouleti, MD,e Fabien Hyafil, MD, PHD,a,b

Dominique Le Guludec, MD, PHD,a,b François Rouzet, MD, PHD,a,b Phalla Ou, MD, PHDb,f

INFECTIOUS AORTITIS (IA) IS A LIFE-THREATENING DISEASE RESULTING FROM THE COLONIZATION OF THE

aorta wall by pathogenic germs. IA generally occurs in pre-disposing conditions (1): 1) a pre-existing vascularlesion: atheromatous plaques or aneurysm; 2) in immunosuppressed patients, because of either comorbiditiesor treatments. IA symptoms are inconsistent and unspecific. Diagnosis relies on blood cultures, frequentlynoncontributive due to previous introduction of antibiotherapy for fever of unknown origin, and on contrast-enhanced computed tomographic angiography (CTA), which implies that the diagnosis was previouslysuspected. The use of positron emission tomography (PET) using fluorodeoxyglucose F-18 (18FDG) as a tracer(18FDG-PET) is widely acknowledged in the management of infectious-related fever, including vascularinfections (2). Here we present 4 cases of IA (Figures 1 to 4), illustrating the additional diagnostic value of asequential multimodal approach combining 18FDG-PET for the screening of infections, including IA, followedby oriented CTA for diagnostic confirmation, guided by 18FDG-PET results.

IA is a life-threatening disease, the diagnosis of which is difficult, often masked by prior antibiotherapy.18FDG-PET, a mainstay in the work-up of infectious diseases, may display patterns evocative of IA that can beconfirmed by CTA. This series suggests IA diagnosis could benefit from a hybrid 18FDG-PET/contrast-enhancedCTA imaging.

From the aDepartment of Nuclear Medicine, Bichat Hospital, Assistance Publique-Hôpitaux de Paris and DHU FIRE, Paris, France;bInserm Unité Mixte de Recherche U1148, LVTS, Paris-Diderot University, Paris, France; cDepartment of Internal Medicine, Bichat

Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France; dUniversité Paris Diderot, PRES Sorbonne Paris Cité, Assistance

Publique Hôpitaux de Paris INSERM U1149 Département Hospitalo-Universitaire FIRE (Fibrosis, Inflammation and Remodelling

in Renal and Respiratory Diseases), Paris, France; eDepartment of Cardiology, Bichat Hospital, Assistance Publique-Hôpitaux de

Paris, Paris, France; and the fDepartment of Radiology, Bichat Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France.

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Manuscript received June 6, 2017; revised manuscript received July 13, 2017, accepted July 14, 2017.

FIGURE 1 IA Through Septic Embolism in an Immunocompromised Patient

PET PET-CT CTA

MIP

FDG-PET

Axial slice

Sagittal slice

Axial slice Axial slice

Sagittal slice Sagittal slice

Mr. R.T., 57 years of age, under immunosuppressive treatment for cardiac graft, was referred for diffuse cutaneous nodules with fever. A skin biopsy showed infection

by Aspergillus fumigatus. Fluorodeoxyglucose F-18 positron emission tomography (18FDG-PET) evidenced multiple cutaneous and muscular focal uptakes (PET/MIP:

green arrow), pulmonary septic embolism (PET/MIP: yellow arrow), as well as vascular abnormalities suggestive of infectious graft: an intense and circumferential

uptake around the descending thoracic aorta wall (PET/MIP, PET, and PET–computed tomography [CT]: red arrow), and 2 foci on left posterior tibial artery and left

fibular artery (PET/MIP: blue arrows). Computed tomographic angiography (CTA) guided by 18FDG-PET results confirmed the dissection of the descending thoracic

aorta (CTA, red arrows), and mycotic aneurysms of the lower limbs arteries. The treatment of this disseminated aspergillosis with embolic infectious aortitis (IA)

consisted of antifungal therapy concomitant with emergent surgical replacement of aorta (confirming the infectious origin). The patient was further discharged with no

associated morbidity. MIP ¼ maximum intensity projection.

CTA PET-CTFDG-PET

Axial slice Axial slice Axial slice

Coronal slice Coronal slice Coronal slice

FIGURE 2 IA by Direct Contamination From aContiguous Infectious Site

Mr. F.B., 50 years of age, was referred to hospital for

fever of unknown etiology. Work-up showed inflamma-

tory syndrome and a left basal lung condensation on

thoracic radiography, suggestive of pulmonary infection.

Despite repeatedly negative blood cultures, empirical

broad-spectrum antibiotherapy was initiated. Given the

persistence of the inflammatory syndrome, an 18FDG-PET

was realized, showing an intense hypermetabolism

circumscribing a left basal pulmonary empyema (green

arrow) and extending to the abdominal aortic wall

(yellow arrow). Subsequent CTA confirmed the existence

of a fissured aneurysm of suprarenal abdominal aorta

(red arrow), adjacent to the pulmonary empyema (blue

arrow), suggestive of IA by direct contamination from

an adjacent foci, a diagnosis made possible by the

combination of both modalities. Treatment consisted of

continuation of the antibiotherapy along with the

surgical replacement of the aneurysm by an aortic graft.

Complementary analysis of the specimens allowed no

microbiological documentation, possibly due to the

previous initiation of antibiotherapy. Abbreviations as

in Figure 1.

Mikail et al. J A C C : C A R D I O V A S C U L A R I M A G I N G , V O L . - , N O . - , 2 0 1 7

Diagnostic Value of Combined Angio-CT and 18FDG-PET - 2 0 1 7 :- –-

2

FIGURE 3 IA on an Aortic-Graft Repair

WBC SPECT 1 WBC SPECT-CT 1

FDG-PET PET-CT

WBC SPECT-CT 2

CTA

Mrs. M.D., 75 years of age, with history of aortic aneurysm, was referred for persistent biological inflammatory syndrome. Bacteriological tests were inconclusive.

Transesophageal echocardiography and CTA displayed a stable aneurysm of the ascending aorta, with no sign of infection. 18FDG-PET was acquired, displaying a focal

FDG uptake regarding the aneurysm (red arrow). Subsequently, radiolabeled white blood cells (WBC) scintigraphy (radiolabeled WBC single-photon emission computed

tomography [SPECT]/CT 1) was realized, showing a focal accumulation of leukocytes, topographically consistent with the FDG uptake (blue arrow), strongly

suggestive of IA. Given the negativity of bacteriological explorations, simple monitoring was advised. Two months later, the patient presented a hemorrhagic stroke,

associated with palmar Janeway lesions. Despite repeatedly negative large-spectrum blood cultures, broad spectrum antibiotherapy was initiated, and 18FDG-PET and

WBC SPECT/CT were repeated, showing the persistence of the abnormal aortic uptake and the appearance of a second focal uptake on the aortic graft. A new CTA

displayed the appearance of an endoluminal floating vegetation attached to the proximal part of the aortic prosthesis (yellow arrow), topographically consistent with

the radiolabeled WBC SPECT 2 (orange arrow). Diagnosis of IA was retained based on the endocarditis-like presentation, with the association of 1 major criteria of the

revised Duke-Li criteria (new partial dehiscence of prosthetic graft on echography, 18FDG-PET uptake), and 3 minor criteria (Janeway lesions, intracranial bleed, and

pre-disposing cardiovascular condition). Therefore, an aortic Bentall replacement and prolongation of antibiotherapy were decided. Specimen analysis evidenced a

suppuration surrounding the proximal part of the aortic prosthesis, with, however, no bacteria on cultures. Consequently, the infectious disease was clinically and

biologically resolved. Abbreviations as in Figure 1.

J A C C : C A R D I O V A S C U L A R I M A G I N G , V O L . - , N O . - , 2 0 1 7 Mikail et al.- 2 0 1 7 :- –- Diagnostic Value of Combined Angio-CT and 18FDG-PET

3

FIGURE 4 IA on Bacteriemia in a Patient With Pre-Existing Intima Breach

FDG-PET CT

CTA

FDG-PET

Mr. J.T., 69 years of age, with record of renal failure, for which he underwent hemodialysis, was referred for fever and Staphylococcus aureus methicillin-sensitive

bacteremia, with no plain portal of entry. Transesophageal echocardiography found no sign of infective endocarditis. He underwent 18FDG-PET exploration, which

revealed the presence of an intense FDG uptake around the descending aorta wall (red arrows), limited to the level of the ninth thoracic vertebra. Aorta showed diffuse

calcifications on CT in relation with atheroma (CT, orange arrow). This aspect suggested IA. Consequently, CTA was performed, showing an ulceration of the aortic

wall, topographically consistent with the abnormalities found on PET (CTA, blue arrows), thus favoring the diagnosis of IA. Treatment consisted in antistaphylococcal

antibiotherapy, allowing the regression of clinical and biological signs of infection. CT without arterial phase could not orient the diagnosis, which was obtained by the

addition of 18FDG-PET to CTA. Abbreviations as in Figure 1.

Mikail et al. J A C C : C A R D I O V A S C U L A R I M A G I N G , V O L . - , N O . - , 2 0 1 7

Diagnostic Value of Combined Angio-CT and 18FDG-PET - 2 0 1 7 :- –-

4

ADDRESS FOR CORRESPONDENCE: Dr. Nidaa Mikail, Bichat-Beaujon Hospital Nuclear Medicine, 46 rue HenriHuchard, Paris 75018, France. E-mail: nidaa.mikail@gmail.com.

RE F E RENCE S

1. Gornik HL, Creager MA. Aortitis. Circulation2008;117:3039–51.

2. MikailN,Benali K,OuP,et al. Detectionofmycoticaneurysms of lower limbs by whole-body (18)F-FDG-PET. J Am Coll Cardiol Img 2015;8:859–62.

KEY WORDS aortitis, CTA, FDG-PET,infectious, multimodality