Semiquantitative Volumetry by Sequential PET/CT May Improve Prediction of Complete Response to Neoadjuvant Chemoradiation in Patients With Distal Rectal Cancer.

BACKGROUND: Previous studies using PET/CT imaging have failed to accurately identify complete responders to neoadjuvant chemoradiation among patients with rectal cancer. The use of metabolic parameters alone or imprecise delineation of baseline and residual tumor volumes may have contributed for these disappointing findings. OBJECTIVE: The purpose of this study was to determine the accuracy of complete response identification in rectal cancer after neoadjuvant chemoradiation by sequential PET/CT imaging with a decrease in tumor metabolism and volume using optimal tumor volume delineation. DESIGN: This was a retrospective comparison of prospectively collected data from a clinical trial (National Clinical Trial 00254683). SETTINGS: The study was conducted at a single research center. PATIENTS: Ninety patients with cT2-4N0-2M0 distal rectal cancer underwent sequential PET/CT at baseline and 12 weeks after neoadjuvant chemoradiation. Quantitative metabolic analysis (median and maximal standard uptake values), volumetric estimates (metabolic tumor volume), and composite estimates incorporating volume and quantitative data (total lesion glycolysis) were compared for the assessment of response to neoadjuvant chemoradiation using receiver operating characteristic curves. Individual standard uptake value thresholds were used according to response to neoadjuvant chemoradiation to match metabolic activity and optimize volume delineation. MAIN OUTCOME MEASURES: The accuracy of complete response identification by multiple volumetric and metabolic parameters using sequential PET/CT imaging was measured. RESULTS: Variation in total lesion glycolysis between baseline and 12-week PET/CT scans was associated with the best area under the curve (area under the curve = 0.81 (95% CI, 0.69-0.92)) when compared with standard uptake value or metabolic tumor volume for the identification of a complete responder. Patients with a ≥92% decrease in total lesion glycolysis between baseline and 12-week PET/CT scan had a 90% chance to harbor complete response. LIMITATIONS: This study was limited by its lack of interobserver agreement analysis. CONCLUSIONS: PET/CT scan using volume and metabolic estimates with individual standard uptake value thresholds for volume determination may provide a useful tool to predict response to neoadjuvant chemoradiation in distal rectal cancer.

18F-FDG PET/CT delayed images after diuretic for restaging invasive bladder cancer.

UNLABELLED: PET with (18)F-FDG has been considered of limited value for detection of bladder cancer because of the urinary excretion of the tracer. The purpose of this study was to investigate the role of PET/CT in the detection and restaging of bladder cancer using furosemide and oral hydration to remove the excreted (18)F-FDG from the bladder. METHODS: Seventeen patients with bladder cancer (11 without cystectomy, 6 with total cystectomy and urinary diversion) underwent (18)F-FDG PET/CT from head to the upper thighs 60 min after the intravenous injection of 370 MBq of (18)F-FDG. Additional pelvic images were acquired 1 h after the intravenous injection of furosemide and oral hydration. PET/CT findings were confirmed by MRI, cystoscopy, or biopsy. RESULTS: PET/CT was able to detect bladder lesions in 6 of 11 patients who had not undergone cystectomy. These images changed the PET/CT final reading in 7 patients: Recurrent bladder lesions were detected in 6 patients, pelvic lymph node metastases in 2 patients, and prostate metastasis in 1. This technique overcame the difficulties posed by the urinary excretion of (18)F-FDG. Hypermetabolic lesions could be easily detected by PET and precisely localized in the bladder wall, pelvic lymph nodes, or prostate by CT. Seven of 17 patients (41%) were upstaged only after delayed pelvic images. CONCLUSION: Detection of locally recurrent or residual bladder tumors can be dramatically improved using (18)F-FDG PET/CT with delayed images after a diuretic and oral hydration.

Normal values of [99mTc]pertechnetate uptake and excretion fraction by major salivary glands.

The assessment of the functional status of the salivary glands has been used in the scintigraphic evaluation of xerostomia. Several quantitative methods derived from standard dynamic scintigraphy have been suggested. However, the indices proposed are quite variable and unlikely to be useful in clinical practice. The objectives of this study were to obtain reference values of major salivary glands uptake and excretion fraction in healthy subjects and to obtain normal ratios of Tc-pertechnetate uptake by the major salivary glands in comparison to the thyroid gland uptake. The standardization of these values has the purpose of making this evaluation faster and more objective. Fifty volunteers without clinical evidence of xerostomia or thyroid disease underwent static salivary glands scintigraphy with Tc-pertechnetate. Static images were obtained at 20 minutes and then at 3 minutes after oral stimulation with lemon juice. Percent uptake, excretion fraction and salivary gland to thyroid ratio rates were calculated for the parotid and the submandibular glands. The mean of the uptake values at 20 minutes for the right and left parotid glands were respectively 0.31% and 0.26%, and for the submandibular glands 0.15%. The excretion fraction of the tracer after the lemon juice stimulation was 70% for the parotids glands, 50% for the right and 49% for the left submandibular glands. The mean+/-SD salivary gland to thyroid count ratio was 0.79+/-0.45 for the right parotid, 0.78+/-0.5 for the left parotid, 0.67+/-0.33 and 0.66+/-0.34 for the right and left submandibular glands, respectively. Salivary glands scintigraphy with uptake and excretion fraction calculation is an easy to perform, non-invasive and objective method to investigate salivary glands function. These findings help the nuclear physician to interpret salivary gland scintigraphy more objectively, even in patients with thyroid gland dysfunction in whom Tc-pertechnetate thyroid uptake may be abnormal.

(18)F-FDG uptake by rectal cancer is similar in mucinous and nonmucinous histological subtypes.

PURPOSE: PET/CT has been considered limited for the evaluation of mucinous colorectal tumors due to low (18)F-FDG uptake. The aim of our study was to compare PET/CT variables in mucinous (MC) and nonmucinous (NMC) rectal adenocarcinomas. METHODS: Consecutive patients with cT2-4N0-2M0 rectal cancer included in a prospective clinical trial were reviewed. PET/CT was performed for primary baseline staging. Visual and quantitative analysis included SUVmax and SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG). PET/CT parameters were compared according to histological subtypes. RESULTS: Overall, 73 patients were included (18 mucinous and 55 nonmucinous). SUVmax values were similar between MC and NMC (19.7 vs. 16.6; p = 0.5). MTV and TLG values were greater in the MC group (103.9 vs. 54.1; p = 0.007 and 892.5 vs. 358.8; p = 0.020) due to larger tumor volumes of MC. CONCLUSIONS: Metabolic parameters at baseline PET/CT for patients with rectal cancer are similar in mucinous and nonmucinous histological subtypes.

Functional electrical stimulation improves brain perfusion in cranial trauma patients.

OBJECTIVE: Demonstrate brain perfusion changes due to neuronal activation after functional electrical stimulation (FES). METHOD: It was studied 14 patients with hemiplegia who were submitted to a program with FES during fourteen weeks. Brain perfusion SPECT was performed before and after FES therapy. These patients were further separated into 2 groups according to the hemiplegia cause: cranial trauma and major vascular insults. All SPECT images were analyzed using SPM. RESULTS: There was a significant statistical difference between the two groups related to patient's ages and extent of hypoperfusion in the SPECT. Patients with cranial trauma had a reduction in the hypoperfused area and patients with major vascular insult had an increase in the hypoperfused area after FES therapy. CONCLUSION: FES therapy can result in brain perfusion improvement in patients with brain lesions due to cranial trauma but probably not in patients with major vascular insults with large infarct area.

Functional electrical stimulation improves brain perfusion in cranial trauma patients / A terapia com estímulo elétrico funcional pode melhorar a perfusão cerebral no SPECT em pacientes com trauma craniano

OBJECTIVE: Demonstrate brain perfusion changes due to neuronal activation after functional electrical stimulation (FES). METHOD: It was studied 14 patients with hemiplegia who were submitted to a program with FES during fourteen weeks. Brain perfusion SPECT was performed before and after FES therapy. These patients were further separated into 2 groups according to the hemiplegia cause: cranial trauma and major vascular insults. All SPECT images were analyzed using SPM. RESULTS: There was a significant statistical difference between the two groups related to patient's ages and extent of hypoperfusion in the SPECT. Patients with cranial trauma had a reduction in the hypoperfused area and patients with major vascular insult had an increase in the hypoperfused area after FES therapy. CONCLUSION: FES therapy can result in brain perfusion improvement in patients with brain lesions due to cranial trauma but probably not in patients with major vascular insults with large infarct area.

OBJETIVO: Demonstrar mudanças na perfusão cerebral devido à ativação neuronal depois de estimulação elétrica funcional (EEF). MÉTODO: Foram estudados 14 pacientes com hemiplegia submetidos a quatorze semanas de um programa com EEF. O SPECT de perfusão cerebral foi realizado antes e depois da terapia com EEF. Estes pacientes foram separados em 2 grupos com relação à causa da hemiplegia: trauma craniano e acidente vascular cerebral (AVC). As imagens de SPECT foram analisadas usando SPM. RESULTADOS: Houve diferença estatisticamente significativa entre os dois grupos relacionada a idade dos pacientes e extensão da hipoperfusão. Os pacientes com trauma craniano tiveram redução na área de hipoperfusão e pacientes com AVC tiveram aumento na área de hipoperfusão após terapia com EEF. CONCLUSÃO: A terapia com EEF pode levar a melhora na perfusão cerebral em pacientes com lesões cerebrais secundárias a trauma craniano; entretanto, provavelmente não em pacientes com extensas áreas de infarto secundárias a AVC.