Single-bed, whole-body 68Ga DOTATATE PET/CT delineation of neuroendocrine tumor metastases

Single-bed, whole-body
68Ga DOTATATE PET/CT delineation of neuroendocrine tumor metastases

By Partha Ghosh, MD, Siemens Healthineers, Hoffman Estates, IL, USA
Data and images courtesy of Inselspital, Bern, Switzerland

|2021-06-01

 A 74-year-old male with a primary duodenal neuroendocrine tumor was referred for 68Ga DOTATATE PET/CT staging to evaluate suspected metastases. One hour and 17 minutes following a 4.3 mCi (158 MBq) intravenous (IV) injection of 68Ga DOTATATE, the patient underwent a 10-minute, single-bed, whole-body PET/CT acquisition on a Biograph Vision Quadrascanner. 

As seen in Figure 1, there are extensive metastases observed throughout the body with lesions in the bone, liver, and intestines. The physiological uptake of radionuclides in the normal liver parenchyma, spleen, kidney, ureter, bladder, bilateral adrenal glands, and pituitary gland appears within normal limits. As observed in Figures 2 and 3, the upper- and lower-most metastatic lesions—ranging from the skull base to the thighs—are sharply defined with equally high contrast-to-background levels due to the Biograph Vision Quadra’s 106 cm axial PET field of view (FoV), which enabled the single-bed, whole-body acquisition for this particular patient measuring 172 cm (5’7”) in height.

There are multiple metastases visualized from the primary neuroendocrine tumor, indicating high somatostatin-receptor density and intense avidity for 68Ga DOTATATE. These findings help inform the recommendation for the patient to proceed with 177Lu DOTATATE radionuclide therapy. By using DOTATATE-labeled ligands, this will help ensure that a similar level of therapeutic tracer intensity within lesions can be achieved for a high and sustained radiation dose to the metastatic lesions without undue normal tissue irradiation.

Although skeletal lesions are possible in the extremities of a patient with a neuroendocrine tumor, metastatic lesions are primarily expected in the vertex-to-mid-thigh region. In this particular case, the 106 cm axial PET FoV enabled vertex-to-mid-thigh imaging, thus providing the accurate visualization of the smallest lesion in the skull base at one end of the FoV as well as the focal marrow metastases in the shaft of the femur at the other end of the FoV—all within a single bed acquisition. Even the smallest lesions with dimensions of 5-6 mm are visualized with precise delineation. There are clinical benefits to be acknowledged in having the ability to conduct single-bed, whole-body imaging, which include reduced scan times and effective doses. In general, the use of the 106 cm axial PET FoV in the PET/CT oncology setting should be adequate in meeting most clinical requirements for oncological conditions requiring vertex-to-mid-thigh imaging.

This case demonstrates the role of 68Ga DOTATATE PET/CT imaging in the evaluation of somatostatin-receptor density within neuroendocrine tumor metastases. The 10-minute, single-bed, whole-body images acquired with Biograph Vision Quadra’s 106 cm axial PET FoV helped define metastatic burden and inform radionuclide therapy plans that involved the use of DOTATATE-labeled ligand.

Scanner: Biograph Vision Quadra

PET

 

CT

Injected dose

4.3 mCi (158 MBq) 68Ga DOTATATE

Tube voltage

120 kV

Post-injection delay

1 hour and 17 minutes

Tube current

80 ref mAs

Acquisition

Single-bed, whole-body; 440 x 440

matrix, PSF+TOF 4i5s, Gaussian filter 2

Slice collimation

32 x 1.2 mm

Scan time
10 minutes