Valor da PET/CT na abordagem do câncer de cabeça e pescoço / Value of PET/CT in the approach to head and neck cancer

OBJETIVO: Avaliar a PET/CT na abordagem de pacientes com câncer de cabeça e pescoço. MATERIAIS E MÉTODOS: Estudo retrospectivo de 63 prontuários e exames de PET/CT de pacientes com câncer de cabeça e pescoço. RESULTADOS: Foram encontradas alterações em 76% dos exames. Destes, 7 (11%) foram considerados falso-positivos, com SUV < 5,0. A PET/CT mostrou-se negativa em 15 situações (24%). Dos 14 casos nos quais se utilizou o exame para estadiamento, em 3 (22%) houve aumento no estadiamento. CONCLUSÃO: A PET/CT mostra-se como exame de potencial valor na rotina de avaliação de pacientes com câncer de cabeça e pescoço, entretanto, necessitamos de maior número de casos para definirmos protocolo de uso.

OBJECTIVE: To evaluate the role of PET/CT in the approach to patients with head and neck cancer. MATERIALS AND METHODS: Retrospective study of medical records and PET/CT images of 63 patients with head and neck cancer. RESULTS: Alterations were observed in 76% of the cases. Out of these cases, 7 (11%) were considered as false-positive, with SUV < 5.0. PET/CT demonstrated negative results in 15 cases (24%). Among the 14 cases where the method was utilized for staging, 3 (22%) had their stages changed. CONCLUSION: PET/CT has shown to be of potential value in the routine evaluation of patients with head and neck cancer, but further studies of a higher number of cases are required to define a protocol for utilization of the method.

Utility of PET in unknown primary with cervical metastasis: A retrospective study.

Background: FDG-PET is recommended as an investigation in unknown primary tumors, but its definitive role and cost effectiveness are yet to be established. Aims: dditional value of FDG-PET over conventional imaging in unknown primary tumors with cervical metastasis. Setting and Design: Retrospective study in a tertiary level oncology centre. Materials and Methods: A total of 112 patients were divided into three groups; 53 with conventional modalities (either computed tomography or magnetic resonance imaging) (group I), 59 with FDG-PET (group II), and group III (subgroup of group II) with both (40 patients). Statistical Analysis: Sensitivity and specificity of both conventional modality and PET were calculated. Association between neck nodes and distant metastasis was analysed using multivariate logistic regression analysis. Results: Sensitivity and specificity for conventional modalities was 92.3% and 50% and sensitivity and specificity of FDG-PET was 92.8% and 71.4%, respectively. FDG-PET detected metastasis in 52.54% of patients. Multivariate logistic regression analysis showed statistically significant association between distant metastasis and multiplicity of nodes (N2b, N2c) (P = 0.007). Among all patients with low neck nodes in group II, FDG-PET detected primaries in 12 patients, 9 of which were infraclavicular (75%). FDG-PET added information to conventional imaging in 32.5% of patients and influenced an overall change in management in 38.9% of patients. Conclusions: FDG-PET is a valuable tool influencing change of management in unknown primary with cervical metastasis. It is recommended especially in the presence of low or multiple neck nodes in view of high incidence of infraclavicular primary and distant metastasis, respectively.

Advanced motion correction methods in PET [review article]

With the arrival of increasingly higher resolution PET systems, small amounts of motion can cause significant blurring in the images, compared to the intrinsic resolutions of the scanners. In this work, we have reviewed advanced correction methods for the three cases of [i] unwanted patient motion, as well as motions due to [ii] cardiac and [iii] respiratory cycles. For the first type of motion [most often studies in PET brain imaging], conventional motion-correction algorithms have relied on extraction of the motion information from the emission data itself. However, the accuracy of motion compensation in this approach is degraded by the noisy nature of the emission data. Subsequently, advanced methods, as reviewed in this work, make use of external real-time measurements of motion. Various image-based and projection-based correction methods have been discussed and compared. The paper also reviews recent and novel applications that perform corrections for cardiac and respiratory motions. Unlike conventional gating schemes, in which the cardiac and respiratory gated frames are independently reconstructed [resulting in noisy images], the reviewed methods are seen to follow a common trend of seeking to produce images of higher quality by making collective use of all the gated frames [and the estimated motion]. As an observation, a general theme in motion-correction methods is seen to be the use of increasingly sophisticated software to make use of existing advanced hardware. In this sense, this field is very open to future novel ideas [hardware, and especially software] aimed at improving motion detection, characterization and compensation