Clinical application of [18F]FDG PET/CT in follicular lymphoma

The objective of the present paper was to review the clinical application of [¹⁸F]FDG PET/CT in follicular lymphoma (FL). Once it was clear that, despite it is characterized as indolent, this type of lymphoma usually shows a high [¹⁸F]FDG avidity, PET/CT became more important and it's now considered the standard technique in staging, re-staging and response evaluation. Many studies have shown its impact on the management of patients (as it can change the stage in a significant proportion of cases and lead to treatment modifications), its superiority over CT (mainly because it's able to distinguish fibrosis in residual masses from viable tumor) and its prognostic value. The latter was initially associated only to the degree of metabolic response, which has proved to be a strong and independent predictive factor in terms of disease-free survival (DFS) and overall survival (OS). Thus, a negative PET/CT scan could be considered a guarantee in high-tumor-burden follicular lymphoma patients. However, semiquantitative parameters such as metabolic tumor volume or total lesion glycolysis, may also provide useful information and help us to identify patients with poor prognosis, guiding a risk-adjusted management and follow-up.

Utility of low dose (18)F-FDG PET-CT in patients with suspected colorectal carcinoma recurrence in conventional diagnostic methods

OBJECTIVE

To evaluate the efficacy of (18)F-FDG PET-CT in the diagnosis of recurrence of colorectal cancer (CRC) in patients with elevated values of carcinoembryonic antigen (CEA) and/or signs of recurrence in the multidetector CT (MDCT), and to demonstrate that good results can be obtained applying the ALARA principles.

MATERIAL AND METHODS

A retrospective study of 54 patients with suspected CRC, who underwent an (18)F-FDG PET-CT, administering a mean dose of 222 MBq (6 mCi) of (18)F-FDG, from 07/2007 to 01/2011 was carried out. Seven patients were excluded, thus studying 47 (27 males, 20 females, mean age 63 years). Recurrence was confirmed by histopathology study in 14 cases and by clinical evolution in 33. The patients were divided into 4 groups. A: patients with elevation of CEA and suspected recurrence in the MDCT. B: elevation of CEA, without suspicious lesions in the MDCT. C: normal levels of CEA and positive MDCT. D: normal levels of CEA and uncertain MDCT.

RESULTS

We found sensitivity, specificity, PPV, NPV and overall accuracy of 91%, 69%, 89%, 75% and 85% respectively. For group A, we found 100% sensitivity, in group B, 75% sensitivity with 100% specificity%, for C, sensitivity was 89% with 71% specificity. Finally, in group D, sensitivity was 100% and specificity 60%, respectively.

CONCLUSION

Applying a low dose, the (18)F-FDG PET-CT has high diagnostic performance in patients with suspicion of CRC, approaching in a higher grade the ALARA criteria.

[Diagnostic value of cardiac 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy in Lewy body disorders]

INTRODUCTION

Lewy body disorders such as Parkinson's disease (PD) and Lewy body dementia (LBD) are associated with cardiac sympathetic denervation, which can be visualized on 123I-MIBG scintigraphy. Our objectives were to study the diagnostic value of this technique in Lewy body disorders and its relationship with PD clinical variables.

PATIENTS AND METHODS

We studied 90 patients: 51 with PD, 19 with LBD, 9 with multiple system atrophy (MSA) and 11 controls. Scintigraphy images were qualitatively evaluated and early and delayed heart-to-mediastinum ratios (HMR) were calculated. The main confounding factors (ischemic heart disease, diabetes, hypertension and drugs) were controlled by multivariate linear regression analysis. We investigated correlations between scintigraphy variables and PD variables.

RESULTS

The delayed HMR, which showed better discriminative ability was 2.03 +/- 0.32 in controls, 1.37 +/- 0.30 in PD (p<0.001 vs controls), 1.47+/-0.45 in LBD (p=0.001 vs controls) and 1.69+/-0.28 in MSA (p=0.02 vs controls; p=0.004 vs PD). This ratio was influenced by PD/LBD diagnosis (beta= -0.638; p<0.001) and to a lesser degree, by ischemic heart disease (beta= -0.244; p=0.028). Optimal cut-off value between PD/LBD and controls was 1.71 (83% sensitivity and 82% specificity). Within the PD group, those with a family history of PD/LB showed higher delayed HMR values (1.65+/-0.34 vs 1.30+/-0.24 without history; p<0.001) and proportion with normal scintigraphy (56% vs 5%; p=0.001).

CONCLUSIONS

Cardiac 123I-MIBG scintigraphy is useful in the diagnosis of Lewy body disorders, although its value in PD is conditioned by having a family history of PD.