A COMPARISON OF I-123 METAIODOBENZYLGUANIDINE SCINTIGRAPHY AND SINGLEBONE-MARROW ASPIRATION BIOPSY IN THE DIAGNOSIS AND FOLLOW-UP OF 26 CHILDREN WITH NEUROBLASTOMA

In staging neuroblastomas, the demonstration of tumoural invasion of t he bone marrow is an important criterion with regard to the therapeuti c prospects and the prognosis. Iliac crest aspiration sampling has bee n used routinely for the detection of bone marrow metastases in neurob lastoma. However, due to the limited character of the sampling, it som etimes leads to false-negative results. Another procedure which is use d to determine the extent of neuroblastoma is metaiodobenzylguanidine (mIBG) scintigraphy. In order to establish the respective merits of bo th diagnostic techniques retrospectively, 148 iodine-123 mIBG scans of 26 children with neuroblastoma have been re-evaluated and compared wi th the results of routine bone marrow samples obtained within a 4-week period before or after scanning. Three types of mIBG uptake in the bo ne/bone marrow could be differentiated: (1) no visualization of the sk eleton; (2) diffuse uptake in the skeleton with or without focally inc reased uptake, which indicates massive, diffuse bone marrow invasion b y the tumour; and (3) focal tracer accumulation in one or several bone s. No tracer uptake was observed in the skeleton in 91 scans. In 89 of the 91 the bone marrow biopsy was negative. Twenty-four scans showed diffuse skeletal uptake with or without foci. The bone marrow biopsies were negative for eight of those 24 scans. Hyperactive foci in one or more bones without diffuse tracer accumulation in the skeleton were d etected in 33 scans. In only 7 of these 33 scans did bone marrow biops y specimens from the iliac MDP crest contain neuroblastoma cells. Avai lable technetium-99m methylene diphosphonate (MDP) whole-body scintigr ams were also compared with the corresponding mIBG scans. Thirty-eight mIBG scans showed no visualization of the skeleton; Tc-99m-MDP scinti grams were also normal. Seven patients with diffuse mIBG uptake in the skeleton appeared as normal on the Tc-99m-MDP scans. Among 27 cases s howing focal mIBG uptake in the skeleton with or without diffuse uptak e, only 18 demonstrated a hot spot on the bone scintigram. The results of our study indicate that for the assessment of bone marrow infiltra tion by neuroblastoma, I-123-mIBG scintigraphy is more sensitive than the conventional cytological examination of bone marrow smears routine ly obtained from the iliac crest, has a very high sensitivity in exclu ding bone marrow invasion, has a high specificity for detecting bone m arrow invasion, appears to be able to detect early tumoural deposits i n the bone marrow before osseous invasion occurs as shown on the MDP s cans and is superior to Tc-99m-MDP bone scan in detecting bone/bone ma rrow metastases of neuroblastoma. In patients with a positive mIBG sca n in the skeleton, bone marrow biopsy will not yield additional inform ation.