Prediction and Diagnosis of Bone Metastases in Well-Differentiated Gastro-Entero-Pancreatic Endocrine Cancer: A Prospective Comparison of Whole Body Magnetic Resonance Imaging and Somatostatin Receptor Scintigraphy

Purpose: Our purpose was to compare the sensitivity of whole body (WB) magnetic resonance imaging (MRI) and somatostatin receptor scintigraphy (SRS) for the diagnosis of bone metastases (BMs) in patients with well-differentiated gastro-entero-pancreatic endocrine cancer (WD-GEP-EC) and to determine predictive factors of BM. Patients and Methods: WB-MRI and SRS were prospectively performed in 79 patients with bronchial (11), thymic (five), gastric (two), duodeno-pancreatic (24), ileal (26), colic (one), or unknown primary (10) WD-GEP-EC. Results: A total of 36 patients (46%) had 333 BMs involving 119 skeletal segments. WB-MRI and SRS were equally sensitive for detecting patients with BM (86 vs. 81%; P = 0.56), with 33% of the patients diagnosed with only one procedure. WB-MRI detected more BMs than SRS (80 vs. 57%; P = 0.017). Compared with SRS, WB-MRI detected more spine BMs (96 vs. 45%; P < 0.001) and tended to detect more pelvic and lower limb BMs (P = 0.054 and P = 0.06, respectively). Compared with WB-MRI, SRS detected more skull BMs (100 vs. 0%; P < 0.001) and tended to detect more rib BMs (P = 0.08). Sternal and upper-limb BMs were equally detected with WB-MRI and SRS (P = 0.32 and P = 0.46, respectively). Bone staging with SRS and spine MRI rather than WB-MRI would have detected 92% of the patients with BMs and 83% of all BMs. The extent of liver involvement and bronchial-thymic primary tumors were independent predictive factors for BM. Conclusions: We recommend bone staging with SRS and spine MRI in all patients with bronchial-thymic or unknown primary WD-GEP-EC. In case of duodeno-pancreatic or ileal primary, bone imaging may be restricted to patients with liver metastases.