Israel Medical Association Journal

Background: Despite the lack of clinical studies supporting the use of routine surveillance FDG-positron emission tomography (PET) in patients with diffuse large B cell lymphoma (DLBCL) who achieved remission, many centers still use this strategy, especially in high risk patients. Surveillance FDG-PET computed tomography (CT) is associated with a high false positive (FP) rate in DLBCL patients. 

Objectives: To investigate whether use of specific CT measurements could improve the positive predictive value (PPV) of surveillance FDG-PET/CT. 

Methods: This retrospective study included DLBCL patients treated with CHOP or R-CHOP who achieved complete remission and had at least one positive surveillance PET. CT-derived features of PET-positive sites, including long and short diameters and presence of calcification and fatty hilum within lymph nodes, were assessed. Relapse was confirmed by biopsy or consecutive imaging. The FP rate and PPV of surveillance PET evaluated with/without CT-derived measurements were compared. 

Results: Seventy surveillance FDG-PET/CT scans performed in 53 patients were interpreted as positive for relapse. Of these studies 25 (36%) were defined as true-positive (TP) and 45 (64%) as FP. Multivariate analysis found long or short axis measuring ≥ 1.5 and ≥ 1.0 cm, respectively, in PET-positive sites, International Prognostic Index (IPI) ≥ 2, lack of prior rituximab therapy and FDG uptake in a previously involved site, to be independent predictors of true positive surveillance PET (odds ratio 5.4, 6.89, 6.6, 4.9, P < 0.05 for all). 

Conclusion: PPV of surveillance PET/CT may be improved by its use in selected high risk DLBCL patients and combined assessment of PET and CT findings.

 

Objectives: To retrospectively determine the clinical response to ¹³¹I-MIBG therapy at low doses in patients with refractory neuroblastoma.

Methods: We performed a retrospective chart review of 10 patients with neuroblastoma treated with ¹³¹I-MIBG at Rambam Health Care Campus from 1994 to 2012. Clinical data, number of ¹³¹I-MIBG courses delivered, toxicities, and clinical responses were reviewed. MIBG scan was performed after each course.

Results: Twenty-one courses of ¹³¹I-MIBG were delivered to 10 patients (3 girls, 7 boys). Their mean age was 3.8 years (range 1.5–6 years). All patients received several protocols of chemotherapy including the high dose form. Three patients received three courses of ¹³¹I-MIBG with a minimum of 6 weeks between each course, five patients received two courses, and two patients received only one course. An objective response to the first course was obtained in nine patients and to the second course in six of eight, and in three children who underwent the third course the pain decreased. One patient has no evidence of disease, four are alive with disease, and five died of the disease. No unanticipated toxicities were observed.

Conclusions: Low dose ¹³¹I-MIBG is an effective and relatively non-toxic treatment in neuroblastoma disease palliation. Rapid and reproducible pain relief with ¹³¹I-MIBG was obtained in most of the children. Treatment with systemic radiotherapy in the form of low dose ¹³¹I-MIBG was easy to perform and effective in cases of disseminated neuroblastoma, demonstrating that this primary therapy can be used for palliative purposes.