Sepsis MRI
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2] Jason Le, B.S.[3]
Synonyms and keywords: sepsis syndrome; septic shock; septicemia
Sepsis MRI
Magnetic resonance imaging (MRI) has no imaging pattern specific for sepsis and is not a first-line or screening study for the undifferentiated septic patient. The 2024 American College of Radiology (ACR) Appropriateness Criteria for Sepsis state that there are no data supporting MRI as an initial or next-line study for undifferentiated sepsis, because most septic patients are too unstable for a relatively long acquisition when faster CT and ultrasound are available. MRI's value is targeted: characterizing a specific, clinically suspected deep source such as musculoskeletal infection, spinal epidural abscess/discitis, perianal or pelvic abscess, or selected hepatobiliary processes, and evaluating suspected sepsis-associated encephalopathy.[1]
Targeted indications
- Musculoskeletal infection: MRI is the study of choice for suspected osteomyelitis, septic arthritis, and deep soft-tissue infection after initial radiographs. A normal MRI can effectively exclude active osteomyelitis, and contrast is useful for characterizing associated soft-tissue infection, abscess, fistula, and vascular complications.[2]
- Spinal infection: Contrast-enhanced spine MRI is the definitive imaging study for suspected spinal epidural abscess or discitis-osteomyelitis, particularly when the source is occult or neurologic findings are present.[3]
- Perianal or pelvic sepsis: MRI can characterize occult perianal or pelvic infection, particularly in neutropenic or immunocompromised patients. Perianal sepsis occurs in up to 10% of neutropenic patients, and pelvic MRI identified a drainable perianal abscess in approximately 88% (8/9) of scanned neutropenic patients in an ACR-cited cohort.[1]
- Selected hepatobiliary sources: MRI/MRCP can characterize suspected biliary obstruction, cholangitis, or hepatic abscess when CT is equivocal or additional soft-tissue or biliary characterization is needed.[1]
- Whole-body MRI: Whole-body MRI can localize multifocal osteomyelitis, intramuscular or solid-organ abscess, myositis, and other occult inflammatory or infectious foci without ionizing radiation, particularly in selected pediatric or immunosuppressed patients. Its use in adult sepsis workflows is not standardized.[4]
Sepsis-associated encephalopathy
Brain MRI is indicated for focal neurologic signs, brainstem symptoms, new-onset seizures, or persistent encephalopathy after metabolic and toxic causes and sedation have been excluded. MRI should include a diffusion-weighted imaging (DWI) sequence and is used chiefly to identify sepsis-associated brain injury and exclude alternative diagnoses such as stroke, central nervous system infection, and posterior reversible encephalopathy syndrome (PRES).[5][6]
- Reported acute-phase MRI findings include parenchymal lesions in approximately 55%, ischemic lesions in 14%-27%, and white-matter lesions in 14%-81% of patients studied for sepsis-associated encephalopathy. Ischemic lesions are often multiple, large, or watershed and have been associated with disseminated intravascular coagulation and lower platelet counts.[5][6]
- Advanced MRI techniques such as magnetic resonance spectroscopy and arterial spin labeling remain investigational for early identification of sepsis-associated encephalopathy and are not established routine diagnostic tests.[7]
Typical MRI findings in infection
- Osteomyelitis: marrow T1 hypointensity, fat-suppressed T2/STIR hyperintensity, and post-contrast enhancement; intraosseous or subperiosteal collections may demonstrate rim enhancement and diffusion restriction.[4][2]
- Abscess: a T2-hyperintense fluid collection with an enhancing rim and central diffusion restriction. Contrast-enhanced imaging and DWI help distinguish a drainable abscess from phlegmon and define the extent of infection.[4][2]
- Septic arthritis: joint effusion with synovial thickening and enhancement; these findings are sensitive but nonspecific and should be correlated with arthrocentesis when septic arthritis is suspected.[4][2]
- Myositis and necrotizing soft-tissue infection: muscle T2 hyperintensity and enhancement with deep fascial fluid or edema. MRI can define the extent of soft-tissue involvement, but it is inferior to CT for depicting soft-tissue gas.[4][2]
Contrast and diagnostic considerations
For peripheral osteomyelitis, intravenous contrast does not substantially improve diagnostic accuracy when noncontrast MRI is already adequate for detection of bone infection, but contrast improves characterization of associated soft-tissue infection, abscess, fistula, and vascular complications.[2]
Gadolinium-based contrast agents may improve detection and characterization of abscess, fistula, necrosis, and vascular complications. Current MRI contrast guidance supports use of appropriate gadolinium-based agents when clinically indicated, with renal function and the clinical indication considered in contrast selection.
Safety and logistics
MRI requires prolonged acquisition in a remote environment with more constrained physiologic monitoring than CT. Do not delay resuscitation, cultures, antimicrobials, or source control to obtain MRI, and stabilize the patient before transport.[1]
Suspected necrotizing soft tissue infection is a surgical diagnosis. Never delay operative exploration for MRI when necrotizing infection is clinically suspected. MRI also depicts soft-tissue gas less well than CT and should not be selected over a faster modality when detection of gas is clinically important.[2]
Clinically actionable recommendations
- Do not use MRI as a first-line or screening study for undifferentiated sepsis; use CT or ultrasound for rapid source evaluation when appropriate.[1]
- Reserve MRI for a specific clinically suspected source that requires its superior soft-tissue, marrow, or neurologic characterization, including musculoskeletal infection, spinal epidural abscess/discitis, perianal or pelvic infection, and selected hepatobiliary processes.[1][2]
- Obtain contrast-enhanced spine MRI urgently when spinal epidural abscess is suspected, particularly with compatible symptoms or neurologic findings.[3]
- Use MRI to define the extent of infection and drainable collections for source-control planning, recognizing that MRI is generally not the modality used to perform drainage itself.[2][4]
- Obtain brain MRI with DWI for sepsis-associated encephalopathy with focal neurologic signs, brainstem symptoms, new-onset seizures, or persistent unexplained encephalopathy, primarily to identify brain injury and exclude alternative diagnoses.[5][6]
- Never delay surgery for suspected necrotizing soft-tissue infection to obtain MRI.[2]
- Stabilize before transport and do not delay time-critical sepsis care for MRI.[1]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Brixey AG, Fung A, De Leon AD; et al. (2024). "ACR Appropriateness Criteria® Sepsis". Journal of the American College of Radiology. 21 (6S): S292–S309. doi:10.1016/j.jacr.2024.02.029.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 Expert Panel on Musculoskeletal Imaging, Pierce JL, Perry MT; et al. (2022). "ACR Appropriateness Criteria® Suspected Osteomyelitis, Septic Arthritis, or Soft Tissue Infection (Excluding Spine and Diabetic Foot): 2022 Update". Journal of the American College of Radiology. 19 (11S): S473–S487. doi:10.1016/j.jacr.2022.09.013.
- ↑ 3.0 3.1 Long B, Gottlieb M. (2025). "Emergency Medicine Updates: Evaluation and Diagnosis of Sepsis and Septic Shock". The American Journal of Emergency Medicine. 90: 169–178. doi:10.1016/j.ajem.2025.01.055. PMID 39892181 Check
|pmid=value (help). - ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Greer MC. (2018). "Whole-body magnetic resonance imaging: techniques and non-oncologic indications". Pediatric Radiology. 48 (9): 1348–1363. doi:10.1007/s00247-018-4141-9.
- ↑ 5.0 5.1 5.2 Sonneville R, Benghanem S, Jeantin L; et al. (2023). "The spectrum of sepsis-associated encephalopathy: a clinical perspective". Critical Care. 27 (1): 386. doi:10.1186/s13054-023-04655-8.
- ↑ 6.0 6.1 6.2 Hosokawa T, Kinoshita K, Ihara S; et al. (2025). "Acute Abnormalities Identified on Brain Magnetic Resonance Imaging in Patients With Sepsis". Neurocritical Care. 43 (2): 437–445. doi:10.1007/s12028-025-02235-y. PMID 40293694 Check
|pmid=value (help). - ↑ Wu S, Wang Y, Song Y; et al. (2023). "Application of Magnetic Resonance Imaging-Related Techniques in the Diagnosis of Sepsis-Associated Encephalopathy: Present Status and Prospect". Frontiers in Neuroscience. 17: 1152630. doi:10.3389/fnins.2023.1152630. PMID 37304016 Check
|pmid=value (help).