COMMENTARY

PET/MRI vs PET/CT for the Detection of Lung Nodules

Hossein Jadvar, MD, PhD, MPH, MBA

Disclosures

November 26, 2013

Pulmonary Nodules in Patients With Primary Malignancy: Comparison of Hybrid PET/MR and PET/CT Imaging

Chandarana H, Heacock L, Rakheja R, et al
Radiology. 2013;268:874-881

Summary

The goal of this investigation was to compare the diagnostic performance of radial T1-weighted gradient-echo (radial volumetric interpolated breath-hold examination [VIBE]) MRI, PET, simultaneous hybrid PET/MRI, and hybrid PET/CT for the detection of 69 lung nodules in 32 patients with cancer of the breast, lung, ovary, endometrium, esophagus, prostate, or skin; sarcoma; osteosarcoma; or lymphoma.

The sensitivity of PET/MRI was 70.3% for all nodules, 95.6% for fluorodeoxyglucose (FDG)-avid nodules, and 88.6% for nodules ≥ 0.5 cm. PET/MRI had significantly higher sensitivity than MRI alone for FDG-avid nodules and higher sensitivity than PET alone for all nodules. There was a strong correlation between measured metabolic activity by PET/CT and PET/MRI. The authors concluded that simultaneous PET/MRI with radial VIBE sequence has high sensitivity for the detection of nodules ≥ 0.5 cm in diameter and FDG-avid nodules.

Viewpoint

Hybrid PET/MRI systems may provide competitive advantages over PET/CT in some clinical settings, and they are now available on the market.[1,2,3] This study from New York University addressed concerns regarding the perceived limitations of PET/MRI compared with PET/CT in depicting lung nodules.

This straightforward clinical study design showed that PET/MRI is generally useful in detecting lung nodules compared with PET/CT, although it may be limited for small non-FDG avid nodules. Small nodules, including micronodules (miliary pattern), may also be missed on PET. However, they are generally depicted well on CT.

Therefore, PET/MRI may have a disadvantage in the detection of micronodularity and possibly for lymphangitic metastatic spread. Nevertheless, it appears that for most clinical situations, PET/MRI offers adequate diagnostic performance for the detection of lung disease, although occasional chest CT may still be needed.

Abstract

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