Tomas G Ohlsson

FDG PET studies during treatment: Prediction of therapy outcome in head and neck squamous cell carcinoma

Positron emission tomography (PET) provides metabolic information of tissues in vivo. The purpose of this study was to assess the value of PET with 2‐[18 F] fluoro‐2‐deoxy‐D‐glucose (FDG) in prediction of therapy outcome (tumor response, survival, and locoregional control) in locally advanced HNSCC.

Lu-177-[DOTA0,Tyr3] Octreotate Therapy in Patients With Disseminated Neuroendocrine Tumors: Analysis of Dosimetry With Impact on Future Therapeutic Strategy

177Lu‐(DOTA0,Tyr3) octreotate is a new treatment modality for disseminated neuroendocrine tumors. According to a consensus protocol, the calculated maximally tolerated absorbed dose to the kidney should not exceed 27 Gy. In commonly used dosimetry methods, planar imaging is used for determination of the residence time, whereas the kidney mass is determined from a computed tomography (CT) scan.

Dose-Fractionated Radioimmunotherapy in Non-Hodgkin's Lymphoma Using DOTA-Conjugated, 90Y-Radiolabeled, Humanized Anti-CD22 Monoclonal Antibody, Epratuzumab.

Purpose: Fractionated radioimmunotherapy may improve therapeutic outcome by decreasing heterogeneity of the dose delivered to the tumor and by decreasing hematologic toxicity, thereby allowing an increased amount of radionuclide to be administered. Because humanized anti-CD22 epratuzumab can be given repeatedly, a single-center study was conducted to establish the feasibility, safety, optimal dosing, and preliminary efficacy of weekly administrations of 90Y-labeled 1,4,7,10-tetra-azacyclodecane-N,N′,N″,N‴-tetraacetic acid–conjugated epratuzumab. Experimental Design: Cohorts of three to six patients with B-cell lymphoma received 185 MBq/m2 [90Y]epratuzumab with unconjugated epratuzumab (total protein dose 1.5 mg/kg) once weekly for two to four infusions, with [111In]epratuzumab coadministered at first infusion for scintigraphic imaging and dosimetry. Results: Sixteen patients received treatment without significant infusional reactions. The overall objective response rate was 62% (95% confidence interval, 39-86%) in both indolent (75%) and aggressive disease (50%). Complete responses (CR/CRu) occurred in 25% of patients and were durable (event-free survival, 14-41 months). Two patients receiving four infusions had hematologic dose-limiting toxicity. Serum epratuzumab levels increased with each weekly dose. Of 13 patients with tumor cell CD22 expression determined by flow cytometry, seven of eight with strongly positive results had objective responses, versus one of five with negative or weakly positive results (P = 0.032). Conclusions: Radioimmunotherapy with weekly 185 MBq/m2 [90Y]epratuzumab achieved a high objective response rate (62%) across lymphoma subtypes, including durable CRs. The findings that three weekly infusions (555 MBq/m2, total dose) can be administered safely with only minor toxicity, that antibody levels increased during treatment weeks, and that therapeutic response predominantly occurs in patients with unequivocal CD22 tumor expression provide guidance for future studies.

Combined (18) F-fluorocholine and (18) F-fluoride positron emission tomography/computed tomography imaging for staging of high-risk prostate cancer.

Study Type – Diagnosis (cohort)

Cerebral glucose metabolism measured by positron emission tomography in term newborn infants with hypoxic ischemic encephalopathy

Total and regional cerebral glucose metabolism (CMRgl) was measured by positron emission tomography with 2-(18F) fluoro-2-deoxy-d-glucose (18FDG) in 20 term infants with hypoxic ischemic encephalopathy (HIE) after perinatal asphyxia. All infants had signs of perinatal distress, and 15 were severely acidotic at birth. Six infants developed mild HIE, twelve moderate HIE, and two severe HIE during their first days of life. The positron emission tomographic scans were performed at 4–24 d of age (median, 11 d). One hour before scanning, 2–3.7 MBq/kg (54–100 μCi/kg) 18FDG was injected i.v. No sedation was used. Quantification of CMRgl was based on a new method employing the glucose metabolism of the erythrocytes, requiring only one blood sample. In all infants, the most metabolically active brain areas were the deep subcortical parts, thalamus, basal ganglia, and sensorimotor cortex. Frontal, temporal, and parietal cortex were less metabolically active in all infants. Total CMRgl was inversely correlated with the severity of HIE (p < 0.01). Six infants with mild HIE had a mean (range) CMRgl of 55.5 (37.7–100.8) μmol·min-1·100 g-1, 11 with moderate HIE had 26.6 (13.0–65.1) μmol·min-1·100 g-1, and two with severe HIE had 10.4 and 15.0 μmol·min-1·100 g-1, respectively. Five of six infants who developed cerebral palsy had a mean (range) CMRgl of 18.1 (10.2–31.4) μmol·min-1·100 g-1 compared with 41.5 (13.0–100.8) μmol·min-1·100 g-1 in the infants with no neurologic sequela at 2 y. We conclude that CMRgl measured during the subacute period after perinatal asphyxia in term infants is highly correlated with the severity of HIE and short-term outcome.

Early Prediction of Treatment Outcome in Head and Neck Cancer with 2-18FDG PET

The development of alternative treatment regimens in clinical oncology has increased the need for early prediction of cancer therapy outcome. The aim of this study was, early in the treatment phase, to identify patients with advanced head and neck cancer, responding or not responding to initiated therapy. The tumour metabolic rate of glucose (MRgl) examined by 2-18FDG-PET was determined in 17 patients before and after the first weeks of either radiotherapy (16-35 Gy) or one course of combination chemotherapy. Metabolic values uptake values normalized to plasma activity integrals--were correlated to loco-regional outcome, as evaluated 5-6 weeks after completion of treatment. Initial low tumour MRgl (<20 micromol/min/100 g tissue), in primary lesions or regional metastases, predicted a local complete response. When a high initial tumour MRgl was found, the magnitude of the reduction of MRgl in the second PET examination might be an adjunct in predicting local tumour response.

Reduced postnatal cerebral glucose metabolism measured by PET after asphyxia in near term fetal lambs

The effects of fetal asphyxia on cerebral function and development, involve the transition from fetal to neonatal life. Changes in cerebral glucose metabolism may be an early postnatal indicator of fetal asphyxia. The objective is to develop an experimental lamb model involving the transition from fetal to neonatal life and to examine the effect of fetal asphyxia with cerebral hypoxic ischemia on early postnatal cerebral glucose metabolism. Fetal asphyxia was induced by total umbilical cord occlusion in eight near‐term fetal lambs (134–138 days) with the ewe under isoflurane‐opiate anesthesia. The mean occlusion time until cardiac arrest was 14.5 (4.2) min (SD). Lambs were immediately delivered and standardized resuscitation was instituted after 2 min asystole. At 4 hr postnatal age, [18‐F]Fluoro‐2‐deoxy‐glucose (18‐FDG) was injected intravenously in eight asphyxiated lambs and in eight controls. Cerebral glucose metabolism was examined by positron emission tomography (PET). As a result the mean arterial blood pressure, acid‐base values, blood glucose and serum lactate at 4 hr postnatal age did not differ significantly between lambs subjected to umbilical cord occlusion and controls. EEG was abnormal in all lambs subjected to cord occlusion and normal in the controls at 4 hr postnatal age. Global cerebral metabolic rate (CMRgl) as determined by PET was significantly lower in lambs subjected to cord occlusion mean/median (SD) 22.2/19.6 (8.4) μmol/min/100 g) than in controls mean/median (SD) 37.8/35.9 (6.1); P < 0.01). Global CMRgl is significantly reduced in newborn lambs 4 hr after fetal asphyxia induced by umbilical cord occlusion. A reduction in CMRgl is an early indicator of global hypoxic cerebral ischemia.

Effect of charge on microvascular permeability in early experimental sepsis in the rat.

A key feature of sepsis is hypovolemia due to increased microvascular permeability. It has been suggested that the negative charge of albumin and of the endothelial glycocalyx is important for maintenance of the normally low permeability for albumin. Here we tested the hypothesis that charge effects contribute to the increased permeability in sepsis. Transcapillary escape rate (TER) and initial distribution volume for (125)I-labeled bovine serum albumin (BSA, isoelectric point pH 4.6) and for (131)I-labeled charge modified BSA (cBSA, average isoelectric point, pH 7.1) was measured 3h after sepsis was induced by cecal ligation and incision (CLI) (n=11) and in control animals (n=12). The importance of charge for permeability in sepsis was estimated by comparing the ratio between TER for cBSA and TER for BSA during control conditions to that after CLI. Plasma concentration of the glycocalyx component glycosaminoglycans (GAGs) was measured in separate control and CLI animals. The initial distribution volume for BSA and cBSA in control animals was 38 ± 3 ml/kg and 47 ± 4 mL/kg and decreased by 17% and 19%, respectively, following CLI. TER for BSA increased from 16.7 ± 4.1% in the controls to 20.1 ± 1.9% following CLI. Corresponding values for cBSA were 26.7 ± 5.6% and 29.8 ± 3.5%, respectively. The ratio between TER for cBSA and TER for BSA was 1.62 ± 0.1 in the control group and 1.49 ± 0.1 following CLI (p<0.05). Plasma GAG concentrations were higher in CLI animals than in the control group. We conclude that CLI induce hypovolemia secondary to increased microvascular permeability. Negative charge contributes to the normally low permeability of albumin and the importance of charge is decreased in early experimental sepsis. The observed charge effects are associated with CLI-induced breakdown of the glycocalyx.

Prediction of patient outcome with 2-deoxy-2-[18F]fluoro-D-glucose-positron emission tomography early during radiotherapy for locally advanced cervical cancer.

Introduction: It is difficult to assess the individual response of locally advanced cervical cancer to chemoradiation therapy during the course of treatment. We have investigated the predictive value of positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) early during treatment in relation to progression-free survival. Methods: This prospective single-center clinical trial included women with locally advanced cervical cancer from 2004 to 2008. 2-Deoxy-2-[18F]fluoro-D-glucose-PET/computed tomography was performed at baseline, during the third week of treatment and, finally, 3 months after the completion of treatment. The images were evaluated visually, semiquantitatively with the maximum standardized uptake value, and by calculating the metabolic rate of FDG. Thirty-two patients were eligible for full evaluation. Results: The median follow-up time was 28 months (range, 5-53 months). Visual metabolic complete response on FDG-PET, after a mean irradiation dose of 23 Gy (range, 16-27 Gy), was found in 7 patients, none of which relapsed. Eleven of the 25 patients with remaining malignant hypermetabolism on the second FDG-PET relapsed. Neither maximum standardized uptake value nor metabolic rate of FDG could further discriminate between patients with low risk and patients with high risk of relapse. The follow-up FDG-PET performed 3 months after the completion of treatment identified a group of patients with poor prognosis. Conclusions: In conclusion, FDG-PET early during chemoradiation therapy identified a small number of patients with an excellent prognosis. However, FDG-PET at this early point in time during treatment failed to predict the outcome for most patients. Future clinical trials to determine the optimal timing of predictive FDG-PET are thus warranted.

FDG-PET in cervical cancer: staging, re-staging and follow-up

Background. Correctly visualising the extent of the disease in cervical cancer is difficult with todays conventional imaging modalities. This paper presents the interim analysis of an on‐going prospective study to evaluate the potential role of FDG‐PET with software fusion with CT images in 3 different clinical settings of cervical cancer. Methods. In Group 1, 10 patients with early stage cervical cancer underwent FDG‐PET 6 months after surgery. Group 2 consisted of 17 patients with locally advanced cervical cancer who underwent FDG‐PET as part of the staging procedure. In Group 3, 12 patients with verified relapse and 3 patients with a strong suspicion thereof underwent FDG‐PET before starting any therapy. The FDG‐PET results were compared with the results of the standard conventional work‐up. All patients had a follow‐up time of at least 6 months. Results. All FDG‐PET scans in Group 1 were true negative. In Group 2, FDG‐PET detected previously unknown locations of metastases in 4 patients, and a synchronous pulmonary carcinoma in 1 patient, resulting in a change in treatment plan for 4 patients. One false negative FDG‐PET result was recorded. In Group 3, FDG‐PET results led to a change in treatment plan for 3 patients. Conclusions. We conclude that FDG‐PET provides crucial information in the pre‐treatment staging procedure in patients with locally advanced or relapsed cervical cancer. However, in the follow‐up of early cervix cancer, FDG‐PET 6 months post‐operatively offered no clinical benefit in this small group of patients.