The “question-mark ” MR anatomy of the cervico-thoracic ganglia complex: can it help to avoid mistaking it for a malignant lesion on 68Ga-PSMA-11 PET/MR?

Abstract

AIM

To investigate the anatomy of cervico-thoracic-ganglia-complex (CTG-C) on MR part of the multimodal ⁶⁸Ga- PSMA)-11 PET/MR imaging on the background of PET features, suggesting malignancy.

METHODS

In 106 patients, 212 sites of the CTG-C were retrospectively reviewed to assess the radiotracer uptake (SUV_max), size, shape, position, symmetry of location and visual uptake intensity. Asymmetry of PSMA-ligand uptake and increased uptake were regarded as risk factors of malignancy.

RESULTS

In 66.0% L(left) and 53.8% R(right) CTG-C we noticed configurations, not previously identified, resembling the shape of a question-mark, an exclamation-mark, or a part of a question mark resembling kidney or comma (called “typical”). Tumor-like CTG-C shapes (oval, binodular or longitudinal) were detected in 28.3% L-CTG-C and in 40.6% R-CTG-C.

When visual assessment of PET suggested malignancy, the recognition of “typical” shape of underlying CTG-C on MR generated a statistically significant rise in the accuracy of their proper identification (from 34.4% to 75%, χ2(1) = 70.4; p < .001). Recognizing the shape of the CTG-C as “typical” in MR allowed us to classify as “not-suspicious” 61.9% of all CTG-C which were treated as “suspicious” after sole PET assessment.

CONCLUSIONS

The characteristic shape of cervico-thoracic-ganglia-complex (resembling a question-mark, including bludgeon-like shape, or its part: kidney-like or comma-like, or an exclamation-mark) on MR part of the multimodal whole-body ⁶⁸Ga-PSMA-ligand PET/MR imaging, seems to be an important adjunct contributing to the proper identification of CTG-C and helps to avoid a diagnostic mistake when PET features suggest possibility of metastasis or other malignancy.