Fig. 8

A patient with metastatic pheochromocytoma, previously treated with left adrenalectomy, presented with rapidly rising metanephrines. ⁶⁸Ga-DOTATATE PET and PET/CT(A) showed intense uptake (Krenning score 4) in a thoracic vertebra, two dominant moderately avid (Krenning score 3) hepatic dome lesions (arrows and arrowheads), and mild to moderately avid soft tissue recurrence in the left upper quadrant surgical bed (brackets). ¹²⁴I-MIBG PET and PET/CT (B) showed intense uptake in the bone metastases, variable uptake in hepatic dome lesions [a lesion with mild uptake (arrowheads) and other with intense uptake (arrows)], and intense uptake in the left upper quadrant soft tissue lesions (brackets). Corresponding CT images showed hypodense lesions in the liver (arrow and arrowhead) and soft tissue nodules in the left upper quadrant (bracket) (C). Due to heterogeneity of tracer uptake on both pre-treatment PET scans and the inability to target all sites of disease using a single therapeutic radiopharmaceutical, the patient underwent tandem treatment with 8 GBq of ¹⁷⁷Lu-DOTATATE and 2.7 GBq of ¹³¹I-MIBG. Post-treatment ¹⁷⁷Lu-DOTATATE SPECT and SPECT/CT (D) showed intense uptake in the bone and both hepatic dome metastases (Krenning score 4) (arrows and arrowheads) but only mild uptake in left upper abdomen soft tissue lesions (brackets). Similar to pre-treatment ¹²⁴I-MIBG PET, post-treatment ¹³¹I-MIBG SPECT and SPEC/CT (E) demonstrated intense uptake in the bone, intense uptake in abdominal left upper quadrant soft tissue lesions (brackets) but in only one of the hepatic lesions (arrows) with no significant uptake in the other (arrowheads), emphasizing the ability to cover disparate molecular imaging phenotypes by using a combination of therapeutic radiopharmaceuticals