Clinical PET-MR Imaging in Breast Cancer and Lung Cancer

Abstract

Hybrid imaging systems have dramatically improved thoracic oncology patient care over the past 2 decades. PET-MR imaging systems have the potential to further improve imaging of thoracic neoplasms, resulting in diagnostic and therapeutic advantages compared with current MR imaging and PET-computed tomography systems. Increasing soft tissue contrast and lesion sensitivity, improved image registration, reduced radiation exposure, and improved patient convenience are immediate clinical advantages. Multiparametric quantitative imaging capabilities of PET-MR imaging have the potential to improve understanding of the molecular mechanisms of cancer and treatment effects, potentially guiding improvements in diagnosis and therapy.

Keywords: Breast cancer; Hybrid imaging; Lung cancer; Oncology; PET-MR imaging; Thoracic imaging.

Fig. 1

54-year-old woman with newly diagnosed left breast cancer. FDG PET-MR imaging performed in the prone position (reoriented) with a dedicated breast coil demonstrates intense FDG uptake in primary tumor on PET and PET-MR images (top right and bottom right). ADC map MR image (bottom left) demonstrates heterogeneous signal intensity with areas of low ADC (grey-black regions) within tumor due to high cellularity. Postcontrast T1-weighted MR image (top left) demonstrates heterogeneous enhancement within the mass. Prone PET-MR imaging with dedicated breast coil facilitates multiparametric quantitative analysis of primary breast tumors. (Courtesy of Dr Amy Melsaether, NYU Langone Medical Center, New York, NY.)

Fig. 2

Left axillary lymph node metastasis in patient presented in Fig. 1. FDG PET-MR image (top left) and PET images (top middle and top right) demonstrate intense radiotracer uptake in a borderline prominent left axillary node. T1-weighted fat-suppressed MR image (bottom left) demonstrates isointense signal intensity of lymph node relative to skeletal muscle. DWI MR image (bottom right) demonstrates high signal intensity of lymph node, and resulting ADC map MR image (bottom middle) demonstrates low signal intensity within central portion of the lymph node in keeping with restricted diffusion. (Courtesy of Dr Amy Melsaether, NYU Langone Medical Center, New York, NY.)

Fig. 3

51-year-old woman with metastatic left breast cancer. FDG PET images (top left and top middle) and PET-MR image (top right) demonstrate large left lung and left pleural metastases, which demonstrate enhancement on post-contrast T1-weighted fat suppressed MR image (bottom left). Note that peripheral rim of FDG uptake in lung metastasiscorresponds to regions of high cellularitywith restricteddiffusion on ADCmap MR image (bottommiddle) derived from DWI MR images (bottom right). (Courtesy of Dr Amy Melsaether, NYU Langone Medical Center, New York, NY.)

Fig. 4

78-year-old woman with bilateral lung cancers. FDG PET-MR image (top left) and PET images (top middle and top right) demonstrate peripheral intense radiotracer uptake in left lung tumor that is most intense medially. ADC map MR image (bottom left) is degraded by motion artifact, a significant challenge for lung nodule imaging. T1-weighted fat-suppressed MR image (bottom middle) and T2-weighted MR image (bottom right) demonstrate heterogeneous signal intensity in the left lower lobe mass.

Fig. 5

64-year-old woman with NSCLC. FDG PET-CT images (top row) demonstrate presumed left adrenal gland metastasis, which is not well-delineated on low-dose unenhanced CT image (top middle) due to relatively low contrast relative to surrounding diaphragm. FDG PET-MR images (bottom row) clearly demonstrate that lesion is a retroperitoneal lymph node (crosshairs) just medial to the left adrenal gland (darker inverted V-shaped structure lateral to crosshairs). Improved soft tissue contrast of MR imaging yielded better lesion localization compared with PET-CT.

Fig. 6

70-year-old woman with NSCLC. FDG PET-MR images (bottom row) identify an enhancing tiny new left cerebellar brain metastasis seen only on postcontrast T1-weighted MR image (bottom middle, see crosshair) and PET-MR image (bottom right, see crosshair). Note that the lesion is not visible on PET images (left column), low-dose unenhanced CT image (top middle), or on PET-CT image (top right).