Structural Properties of Inverted Hexagonal Phase: A Hybrid Computational and Experimental Approach.

Inverted/reverse hexagonal (HII) phases are of special interest in several fields of research, including nanomedicine. We used molecular dynamics (MD) simulation to study HII systems composed of dioleoylphosphatidylethanolamine (DOPE) and palmitoyloleoylphosphatidylethanolamine (POPE) at several hydration levels and temperatures. The effect of the hydration level on several HII structural parameters, including deuterium order parameters, was investigated. We further used MD simulations to estimate the maximum hydrations of DOPE and POPE HII lattices at several given temperatures. Finally, the effect of acyl chain unsaturation degree on the HII structure was studied via comparing the DOPE with POPE HII systems. In addition to MD simulations, we used deuterium nuclear magnetic resonance (2H NMR) and small-angle X-ray scattering (SAXS) experiments to measure the DOPE acyl chain order parameters, lattice plane distances, and the water core radius in HII phase DOPE samples at several temperatures in the presence of excess water. Structural parameters calculated from MD simulations are in excellent agreement with the experimental data. Dehydration decreases the radius of the water core. An increase in hydration level slightly increased the deuterium order parameter of lipids acyl chains, whereas an increase in temperature decreased it. Lipid cylinders undulated along the cylinder axis as a function of hydration level. The maximum hydration levels of PE HII phases at different temperatures were successfully predicted by MD simulations based on a single experimental measurement for the lattice plane distance in the presence of excess water. An increase in temperature decreases the maximum hydration and consequently the radius of the water core and lattice plane distances. Finally, DOPE formed HII structures with a higher curvature compared to POPE, as expected. We propose a general protocol for constructing computational HII systems that correspond to the experimental systems. This protocol could be used to study HII systems composed of molecules other than the PE systems used here and to improve and validate force field parameters by using the target data in the HII phase.

Value of EUS in Determining Curative Resectability in Reference to CT and FDG-PET: The Optimal Sequence in Preoperative Staging of Esophageal Cancer?

BACKGROUND: The separate value of endoscopic ultrasonography (EUS), multidetector computed tomography (CT), and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the optimal sequence in staging esophageal cancer has not been investigated adequately. METHODS: The staging records of 216 consecutive operable patients with esophageal cancer were reviewed blindly. Different staging strategies were analyzed, and the likelihood ratio (LR) of each module was calculated conditionally on individual patient characteristics. A logistic regression approach was used to determine the most favorable staging strategy. RESULTS: Initial EUS results were not significantly related to the LRs of initial CT and FDG-PET results. The positive LR (LR+) of EUS-fine-needle aspiration (FNA) was 4, irrespective of CT and FDG-PET outcomes. The LR+ of FDG-PET varied from 13 (negative CT) to 6 (positive CT). The LR+ of CT ranged from 3-4 (negative FDG-PET) to 2-3 (positive FDG-PET). Age, histology, and tumor length had no significant impact on the LRs of the three diagnostic tests. CONCLUSIONS: This study argues in favor of PET/CT rather than EUS as a predictor of curative resectability in esophageal cancer. EUS does not correspond with either CT or FDG-PET. LRs of FDG-PET were substantially different between subgroups of negative and positive CT results and vice versa.

Prognostic impact of clinicopathological features and expression of biomarkers related to (18)F-FDG uptake in esophageal cancer.

PURPOSE: To analyze the association between pretreatment 18-F-fluoro-deoxyglucose (FDG) uptake and characteristics of aggressive tumor biology in predicting outcome in esophageal cancer (EC). METHODS: Tumor FDG-uptake was measured by maximum standardized uptake values (SUVmax) in 47 patients undergoing esophagectomy with curative intent. ROC analyses were used to predict an optimal SUVmax cutoff for survival. Expression of hexokinase-II (HK-II), glucose transporter I (GLUT-I), hypoxia inducible factor-1α (HIF-Iα), vascular endothelial growth factor-C (VEGF-C), p53, and proliferative activity (Ki-67) were correlated with SUVmax values and clinicopathological characteristics. RESULTS: A SUVmax > 3.67 predicted a significantly lower disease-free survival (DFS) and distant recurrence-free survival (p = 0.022 and p = 0.005). High HK-II expression was correlated with reduced SUVmax values (p = 0.002) and was significantly higher in esophageal adenocarcinoma compared with squamous cell carcinoma (p = 0.005). Preoperative high FDG uptake in primary tumors was associated with nodal metastases (pN1; Spearman correlation 0.39, p = 0.01). We found no positive correlation between SUVmax and GLUT-1, HK-1, HIF-Iα 1, VEGF-C, p53, and Ki-67 expression. CONCLUSIONS: High preoperative FDG-uptake strongly predicts poor survival outcome and is associated with lymph node metastases in EC patients. HK-II expression was related to SUVmax and DFS.

First-line erlotinib and bevacizumab in patients with locally advanced and/or metastatic non-small-cell lung cancer: a phase II study including molecular imaging.

BACKGROUND: Both bevacizumab and erlotinib have clinical activity in non-small-cell lung cancer (NSCLC). Preclinical data suggest synergistic activity. PATIENTS AND METHODS: Chemonaive patients with stage IIIb or IV non-squamous NSCLC were treated with bevacizumab 15 mg/kg every 3 weeks and erlotinib 150 mg daily until progression. Primary end point was non-progression rate (NPR) at 6 weeks. Tumor response was measured with computed tomography, 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG-PET) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). KRAS and EGFR mutations were assessed in tumor samples. RESULTS: Forty-seven patients were included. Median follow-up was 15.2 months. NPR at 6 weeks was 75%. Median progression-free survival (PFS) was 3.8 [95% confidence interval (CI) 2.3-5.4] months and median overall survival (OS) was 6.9 (95% CI 5.5-8.4) months. Toxicity was mainly mild. The presence of KRAS (n = 10) or EGFR mutations (n = 5) did not influence outcome. After 3 weeks of treatment, >20% decrease in standard uptake value as measured with positron emission tomography predicted for longer PFS (9.7 versus 2.8 months; P = 0.01) and >40% decrease in K(trans) as assessed by DCE-MRI did not predict for longer PFS. CONCLUSIONS: First-line treatment with bevacizumab and erlotinib in stage IIIb/IV NSCLC resulted in an NPR of 75%. OS was however disappointing. Early response evaluation with FDG-PET is the best predictive test for PFS.

Cortico-thalamic activation in generalized status epilepticus, a PET study.

In a patient with a refractory generalized convulsive status epilepticus, the ictal distribution of regional cerebral glucose was assessed with positron emission tomography (PET). Synchronized seizure activity in the EEG was associated with bilateral metabolic activation of medial sensorimotor regions, anterior cingulate cortex, striatum and thalamus. This pattern with focal cortical activation supports the concept that a cortical focus may drive epilepsy, while the thalamus mediates synchronization of neuronal activity as reflected in the EEG.

What is the value of emission tomography studies in patients with a primary glioblastoma multiforme treated by 192Ir brachytherapy?

BACKGROUND: We studied the use of (201)Thallium SPECT and L-[1-(11)C]-tyrosine PET in patients with a primary glioblastoma multiforme treated with (192)Ir brachytherapy after surgery and external beam radiation therapy. We hypothesised that the patients most likely to benefit from further surgery after deterioration would be those with radiation necrosis and would be recognised by a negative emission tomography scan. METHODS: Twenty-one patients underwent (201)Thallium SPECT performed before brachytherapy, and this was repeated in 19 patients when recurrence was suspected. Nine patients also underwent a PET scan at the same time. Nine patients underwent a second operation. FINDINGS: SPECT and PET were highly concordant concerning the prediction of radionecrosis and/or tumour recurrence. Repeat surgery did not lead to a significant increase in survival. There was no significant association between the duration of survival and tumour-to-background ratio but the number studied was small. Both SPECT and PET showed highly active lesions, which were proved to be recurrent tumour by clinical and histological follow-up. CONCLUSION: Although PET and SPECT are both highly sensitive in detecting active tumour tissue, emission tomography was not clinically valuable in the investigation of patients with a primary glioblastoma treated with brachytherapy.

Systematic review of the staging performance of 18F-fluorodeoxyglucose positron emission tomography in esophageal cancer.

PURPOSE: Despite the increasing number of publications concerning (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) for staging of esophageal cancer and the increasing availability of this novel diagnostic modality, its exact role in preoperative staging of these tumors is still unknown. The aim of this study was to systematically review the literature regarding the diagnostic performance of FDG-PET in preoperative staging of patients with esophageal cancer, and to calculate summary estimates of its sensitivity and specificity. METHODS: The databases of PubMed, Embase, and Cochrane were searched for relevant studies. Two reviewers independently assessed the methodological quality of each study. A meta-analysis of the reported sensitivity and specificity of each study was performed. RESULTS: Twelve studies met the inclusion criteria. The studies had several design deficiencies. Pooled sensitivity and specificity for the detection of locoregional metastases were 0.51 (95% CI, 0.34 to 0.69) and 0.84 (95% CI, 0.76 to 0.91), respectively. For distant metastases, pooled sensitivity and specificity were 0.67 (95% CI, 0.58 to 0.76) and 0.97 (95% CI, 0.90 to 1.0), respectively. CONCLUSION: FDG-PET showed moderate sensitivity and specificity for the detection of locoregional metastases, and reasonable sensitivity and specificity in detection of distant lymphatic and hematogenous metastases.

No difference in cardiac event-free survival between positron emission tomography-guided and single-photon emission computed tomography-guided patient management: a prospective, randomized comparison of patients with suspicion of jeopardized myocardium.

OBJECTIVES: We sought to prospectively compare nitrogen-13 (13N)-ammonia/18fluorodeoxyglucose (18FDG) positron emission tomography (PET)-guided management with stress/rest technetium-99m (99mTc)-sestamibi single-photon emission computed tomography (SPECT)-guided management. BACKGROUND: Patients with evidence of jeopardized (i.e., ischemic or viable) myocardium may benefit from revascularization, whereas patients without it should be treated with drugs. Both PET and SPECT imaging have been proven to delineate jeopardized myocardium. When patient management is based on identification of jeopardized myocardium, it is unknown which technique is most accurate for long-term prognosis. METHODS: In a clinical setting, 103 patients considered for revascularization with left ventricular wall motion abnormalities and suspicion of jeopardized myocardium underwent both PET and SPECT imaging. The imaging results were used in a randomized fashion to determine management (percutaneous transluminal coronary angioplasty [PTCA], coronary artery bypass graft surgery [CABG] or drug treatment). Follow-up for cardiac events (cardiac death, myocardial infarction and revascularization) was recorded for 28 +/- 1 months. The study was designed to have a power of 80% to detect a 20% difference in the event rate between PET- and SPECT-based management. RESULTS: Management decisions in 49 patients randomized to PET (12 who had PTCA, 14 CABG and 23 drug therapy) were comparable with 54 patients randomized to SPECT (15 who had PTCA, 13 CABG and 26 drug therapy). In terms of cardiac event-free survival, no differences between PET and SPECT were observed (11 vs. 13 cardiac events for PET and SPECT, respectively; p = NS by the Kaplan-Meier statistic). CONCLUSIONS: No difference in patient management or cardiac event-free survival was demonstrated between management based on 13N-ammonia/18FDG PET and that based on stress/rest 99mTc-sestamibi SPECT imaging. Both techniques may be used for management of patients considered for revascularization with suspicion of jeopardized myocardium.

Assessment of methylphenidate-induced changes in binding of continuously infused [(11)C]-raclopride in healthy human subjects: correlation with subjective effects.

RATIONALE: The dopaminergic system has been implicated in the pathogenesis and treatment of a variety of neuropsychiatric disorders. It has been shown that information on endogenous dopamine (DA) release can be obtained noninvasively by combining positron emission tomography with a dopaminergic challenge. This approach is based on the assumption that an injected radiolabeled ligand competes with the neurotransmitter for the same receptor. Increases in DA release will therefore result in a decreased binding of the radioligand. OBJECTIVES: We investigated the effect of the DA reuptake blocker methylphenidate (MP) on the binding of the D(2) receptor ligand [(11)C]-raclopride (RAC). METHODS: The effect of a 0.25 mg/kg intravenous dose of MP was studied in six healthy volunteers. RAC was administered as a bolus followed by constant infusion, and subjective effects were assessed using verbal rating scales. RESULTS: Control scans without MP administration showed that the mean RAC binding reached stable values approximately 30 min after start of the infusion. MP administration induced a 24% decrease in RAC binding in the total striatum. Correlations were found between the MP-induced change in euphoria and the percent change in binding potential (DeltaBP) in the dorsal striatum and between baseline anxiety and DeltaBP in the dorsal and middle striatum. We also found a negative correlation between baseline BP in the dorsal striatum and change in euphoria. CONCLUSIONS: Our results comply with previous findings, indicating the feasibility of the bolus infusion design combined with a relatively low MP dose to study dopaminergic (dys)function.

The nigrostriatal dopaminergic system in familial early onset parkinsonism with parkin mutations.

Nigrostriatal dopaminergic function and cerebral energy metabolism were measured with PET in two brothers with early-onset parkinsonism caused by mutation of the parkin gene. Energy metabolism did not differ, but the nigrostriatal dopaminergic pattern was clearly different than that of sporadic PD. Thus parkinsonism in these two patients was shown to be pathophysiologically different than PD.

Measurement of clinical and subclinical tumour response using [18F]-fluorodeoxyglucose and positron emission tomography: review and 1999 EORTC recommendations. European Organization for Research and Treatment of Cancer (EORTC) PET Study Group.

[18F]-fluorodeoxyglucose ([18F]-FDG) uptake is enhanced in most malignant tumours which in turn can be measured using positron emission tomography (PET). A number of small clinical trials have indicated that quantification of the change in tumour [18F]-FDG uptake may provide an early, sensitive, pharmacodynamic marker of the tumoricidal effect of anticancer drugs. This may allow for the introduction of subclinical response for anticancer drug evaluation in early clinical trials and improvements in patient management. For comparison of results from smaller clinical trials and larger-scale multicentre trials a consensus is desirable for: (i) common measurement criteria; and (ii) reporting of alterations in [18F]-FDG uptake with treatment. This paper summarises the current status of the technique and recommendations on the measurement of [18F]-FDG uptake for tumour response monitoring from a consensus meeting of the European Organization for Research and Treatment of Cancer (EORTC) PET study group held in Brussels in February 1998 and confirmed at a subsequent meeting in March 1999.

Nodal spread of squamous cell carcinoma of the oral cavity detected with PET-tyrosine, MRI and CT.

UNLABELLED: The uptake of L-1-[11C]-tyrosine (TYR) in cervical lymph nodes of eleven patients with squamous-cell carcinoma (SCC) of the oral cavity was studied with PET to detect lymphogenic metastases. METHODS: The TYR-PET results were compared with clinical, MRI, CT, histopathologic findings and historical data of patients studied with FDG. Sensitivity, specificity, accuracy and the positive and negative predictive values were calculated. RESULTS: TYR-PET had sensitivity of 83% and a specificity of 95%. In contrast, the sensitivity and specificity for MRI were 33% and 96%, respectively. The sensitivity and specificity for CT were 55% and 91%, respectively. TYR-PET results compared favorably with FDG. CONCLUSION: With TYR-PET, SCC metastases of the oral cavity can be visualized with high sensitivity and specificity. TYR-PET can be an additional tool for further evaluation of neck malignancies.

Proliferative activity in human brain tumors: comparison of histopathology and L-[1-(11)C]tyrosine PET.

UNLABELLED: To validate the protein synthesis rate (PSR) measured in human brain tumors using L-[1-(11)C]tyrosine (TYR) PET, the PSR was compared to histopathological parameters that reflect proliferation and protein synthesis. METHODS: We studied 20 patients who had a brain biopsy and who also underwent a PET study with TYR. Paraffin sections were stained with the monoclonal antibody MIB 1, targeted against the core antigen Ki-67, and nucleolar organizer regions (NORs) were measured as argyrophilic NORs (AgNORs). The TYR uptake was measured by PET, and with a kinetic model, the PSR was determined. RESULTS: PSR (nmol/ml/min) ranged from 0.44 to 1.99 (mean, 0.97), Ki-67 labeling indices (%) ranged from 0.9 to 33.5 (mean, 9.5) and AgNOR area (mm2/cm2) ranged from 0.13 to 0.85. No relationship was found between PSR and Ki-67 labeling index or AgNOR area. CONCLUSION: It seems that the PSR and proliferation, as measured by Ki-67, are independent processes. The role of the PSR is uncertain, but it is likely that it can be seen as a marker for the homeostasis of the cell.

Posterolateral defect of the normal human heart investigated with nitrogen-13-ammonia and dynamic PET.

UNLABELLED: The posterolateral defect is a common artifact seen when static 13N-ammonia imaging with PET is used to assess myocardial perfusion. The aim of this study was to compare dynamic and static. 13N-ammonia PET and to obtain more insight into the cause of the posterolateral defect. METHODS: Dynamic 13N-ammonia PET was performed in 19 healthy nonsmoking volunteers at rest. Perfusion was assessed in the early phase of the study using a curve fit method over the first 90 sec. Nitrogen-13 accumulation (static PET) was assessed 4 to 8 min after injection. Each study was normalized to a mean of 100. The average distribution of normalized perfusion and activity was calculated in 24 segments. Heterogeneity of both activity and perfusion distribution were assessed and the activity distribution was compared with perfusion distribution. RESULTS: Perfusion distribution was homogeneous, with the exception of the inferior and apical regions. Activity distribution was inhomogeneous, with a lower activity in the posterolateral and apical regions. In the whole left ventricle, significant differences in distribution were found between static and dynamic imaging. CONCLUSION: Perfusion distribution was significantly different on dynamic images compared to static images. The posterolateral defect was not found on dynamic images. The posterolateral defect and other inhomogeneities in activity distribution are caused by tracer-dependent features, probably a redistribution of metabolites of 13N-ammonia.

Quantitative myocardial mapping of perfusion and metabolism using parametric polar map displays in cardiac PET.

UNLABELLED: Most efficacy studies of cardiac PET in demonstrating myocardial ischemia and viability have been performed using one or more transversal static images of the heart. In contrast, in this paper we describe a method of functional imaging of the complete left ventricular myocardium for perfusion with nitrogen-13-ammonia, both at rest and during a dipyridamol stress test, and of glucose metabolism with 18F-fluorodeoxyglucose (18FDG). METHODS: This was performed by using the data of each of 48 radial segments of 10 short-axis images as tissue data and LV cavity data of three basal planes as blood pool data. The study describes the results of 19 normal volunteers and 36 patients with coronary artery disease. From the data of the normal volunteers a 95% normal confidence interval was calculated for each imaging modality. These intervals were then used to describe the patient data as normal, ischemic or infarcted. RESULTS: The results of analysis of the parametric images was compared with the results of static analysis of the same patient data and found to be less dependant on the detection threshold used. CONCLUSION: The described method enables the routine application of functional PET imaging of the total myocardium by the semi-automatic construction of parametric flow and metabolism polar maps. It thus provides an increased performance in the diagnosis, quantification and localization of myocardial ischemia and viability over conventional PET imaging.

Detection of lymph node metastases of squamous-cell cancer of the head and neck with FDG-PET and MRI.

UNLABELLED: The uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) in neck lymph nodes of twelve patients with a squamous-cell carcinoma of the oral cavity was studied with PET in order to detect and locate lymphogenic metastases. METHODS: The results of FDG-PET imaging were compared with clinical, MRI and histopathologic findings. Standardized uptake values (SUV) were also calculated. RESULTS: A sensitivity of 91% and a specificity of 88% were calculated for FDG-PET. In contrast, a sensitivity of 36% and a specificity of 94% were calculated for MRI. Calculated SUVs for reactive lymph nodes, metastatic lymph nodes and the primary tumor were undifferentiated. CONCLUSION: Using FDG-PET, lymph node metastases of squamous-cell carcinomas of the oral cavity can be visualized with a high sensitivity and specificity. FDG-PET can be an improvement in the evaluation of the neck.

In vivo protein synthesis rate determination in primary or recurrent brain tumors using L-[1-11C]-tyrosine and PET.

UNLABELLED: The applicability of protein synthesis rate (PSR) determination with L-[1-11C]tyrosine (11C-TYR) and PET was assessed in patients suspected of a primary or recurrent brain tumor. METHODS: Simultaneous to intravenous injection of 265 MBq of 11C-TYR, dynamic PET acquisition was started and continued for 50 min. Arterial samples were taken and analyzed for 11C-TYR and metabolites. Based on this data, a model was proposed and the corresponding PSR calculated. RESULTS: Plasma metabolites were 11CO2, 11C-proteins and 11C-L-DOPA, constituting more than 50% of total plasma radioactivity at 40 min postinjection. Plasma 11CO2 reached a plateau of around 25% of total plasma radioactivity at 20 min postinjection. Plasma 11C-protein was not detected before 10 min postinjection, but increased exponentially afterwards to 20% at 40 min postinjection. Plasma 11C-L-DOPA was the only acid-soluble radioactive metabolite detected and was less than 8% at 40 min postinjection. Using a five-compartment model, it was shown that while the net PSR was dependent on the recycling of amino acids from protein, the amino acid incorporation was not, which was thus used for subsequent analysis. It was found that our curve-fitting results were unreliable due to the exchange of 11C-TYR between plasma and erythrocytes whereas the graphical Patlak-Gjedde analysis is hardly influenced by this transport phenomenon. The average amino acid incorporation rate thus calculated was 0.7 nmole/ml.min for nontumor tissue with a tumor versus nontumor average ratio of 1.7. CONCLUSION: The assessment of the PSR with TYR-PET is valuable and relatively simple to implement clinically.

Fluorine-18-fluorodeoxyglucose PET imaging of soft-tissue sarcoma.

UNLABELLED: PET with 18F-fluoro-2-deoxy-D-glucose (FDG) was used to study soft-tissue lesions. The goals of the study were to establish FDG uptake in soft-tissue sarcoma, to determine the sensitivity of this technique, to investigate the correlation between histologic grade and glucose consumption and to determine whether FDG-PET can discriminate between benign and malignant lesions. METHODS: PET imaging was performed in 18 patients with soft-tissue sarcoma and 4 patients with a benign soft-tissue lesion. Glucose consumption in the tumors was calculated using Patlak's graphical analysis with an assumption made for the lumped constant. Standardized uptake values also were calculated. RESULTS: All soft-tissue sarcomas were clearly depicted. The median glucose consumption was 13.0 mumole/100 g/min (range 2.9-41.8 mumole/100 g/min). A correlation was found between glucose metabolism and the histopathologic malignancy grade. Such a correlation was not demonstrated for the standardized uptake values. One benign lesion was also visualized. Benign lesions were not visualized in two patients and in the remaining patient an equivocal scan was obtained. Benign lesions could be distinguished from high-grade malignant lesions but not consistently from lesions with low or intermediate malignancy grades. CONCLUSION: PET with FDG is an effective technique to visualize soft-tissue sarcomas. We found a sensitivity of 100%. There is a correlation between glucose metabolic rate and tumor malignancy grade. FDG appears to be unsuitable for discriminating benign lesions from soft-tissue sarcomas with low or intermediate malignancy grades.

Standardized uptake value and quantification of metabolism for breast cancer imaging with FDG and L-[1-11C]tyrosine PET.

UNLABELLED: The aims of the study were to compare the value of L-[1-11C]tyrosine (TYR) and [IBF]fluoro-2-deoxy-D-glucose (FDG) as tumor tracers in patients with breast cancer, to investigate the correlation between quantitative values and standardized uptake values (SUVs) and to estimate the value of SUVs for the evaluation of therapy. METHODS: Eleven patients with one or more malignant breast lesions and two patients with one or more benign breast tumors were studied with TYR and FDG. Doses of 300 MBq of TYR and 230 MBq of FDG were given intravenously. All PET sessions were performed using a Siemens ECAT 951/31 camera. Of 10 malignant tumors and the 3 benign lesions, glucose consumption and protein synthesis rate were quantified. All lesions were studied using SUVs based on body weight, body surface area and lean body mass, with and without correction for plasma glucose or tyrosine levels. RESULTS: All malignant tumors were visualized with both FDG and TYR, but the visual contrast was better with FDG. Increased uptake of the tracers was seen in patients with fibrocystic tissue and complicated the visual assessment and the outlining of tumor tissue. Uptake in fibrocystic disease was more prominent with FDG than with TYR. No difference in tumor/nontumor ratio between the two tracers could be established. FDG showed a false-positive result in one benign lesion. No major differences between the SUVs as defined above were found, although the best correlation between glucose consumption and the SUV was observed when the SUV was based on body surface area and corrected for plasma glucose level (r = 0.85-0.87). The SUV based on lean body mass was found to correlate best with protein synthesis rate (r = 0.83-0.94). CONCLUSION: In this group of patients, TYR appears to be a better tracer than FDG for breast cancer imaging, because of lower uptake in fibrocystic disease. SUVs correlate well with quantitative values, but future studies must determine whether treatment evaluation is also reliable with SUVs.

PET with L-[1-carbon-11]-tyrosine to visualize tumors and measure protein synthesis rates.

UNLABELLED: We studied the potential of PET with L-[1-11C]-tyrosine (TYR) to visualize tumors outside the central nervous system and to quantify their protein synthesis rates (PSRs). METHODS: Twenty-two patients suspected of having a malignant tumor underwent a PET study with TYR before biopsy. The PSR in nanomoles per milliliter tumor tissue per minute as well as the PSR in contralateral normal tissue, standardized uptake values (SUVs) and tumor-to-nontumor-ratios (T/N ratios) were calculated. RESULTS: Fifteen of the 16 malignancies (94%) were correctly visualized as a hot spot. A chondrosarcoma of the sacrum was not visualized. Of the six patients with benign lesions, cold spots were correctly identified in four (67%). A benign schwannoma and an intramuscular hemangioma of the forearm were visualized as hot spots. PSR in tumor tissue was higher than in the corresponding contralateral normal tissues. PSR and SUV in malignant tumors were higher than in benign tumors. CONCLUSION: TYR appears to be a good tracer for imaging malignancies. The PSR, which was higher in malignant tumors than in normal tissue and the studied benign lesions, could be quantified and correlated with the SUV.