FDG Positron Emission Tomography Scans Research Articles

Longitudinal Changes in Glucose Metabolism of Denervated Muscle after Complete Peripheral Nerve Injury.

Electrodiagnostic studies can obtain information 2 or 3weeks after an acute nerve injury. Previous studies have shown increased glucose metabolism in denervated muscles 1week after injury using 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) positron emission tomography (PET). Therefore, this study aimed to evaluate the changes in glucose metabolism in denervated muscles using serial monitoring by [(18)F]FDG PET scans. Denervation was induced in eight male Sprague-Dawley rats (aged 7weeks old) weighing 200-250g. The right legs of the rats were denervated by resecting the sciatic nerve in the thigh after the initial skin incision. Two rats were sacrificed 1 and 10weeks after denervation. Skeletal muscles (gastrocnemius and tibialis anterior) were excised from both the right and left legs of the rats. Staining with hematoxylin and eosin, glucose transporter (GLUT)-1, GLUT-4, and hexokinase II was undertaken. PET/computed tomography (CT) scans were performed on the six remaining rats a total of five times at 1, 2, 5, 8, and 10weeks after denervation. Regions of interest were drawn on integrated PET/CT images to measure the degree of [(18)F]FDG uptake in the right and left lower leg muscles. Target-to-background ratios (TBRs) were calculated by dividing the FDG uptake of the lower leg muscles by that of the upper leg muscles. The TBRs of the denervated muscles were higher than those of the control muscles at both 1 (6.84 ± 1.98 vs. 1.18 ± 0.11, p = 0.009) and 2 (4.10 ± 2.05 vs. 1.86 ± 0.73, p = 0.0374) weeks after denervation. After 5 (2.18 ± 0.78 vs. 1.35 ± 0.47, p = 0.1489), 8 (1.76 ± 0.18 vs. 1.69 ± 0.18, p = 0.5127), and 10 (1.76 ± 0.52 vs. 1.56 ± 0.37, p = 0.5637) weeks, the difference in the TBRs between the denervated and controls became non-significant. [(18)F]FDG PET can visualize increased glucose metabolism in a denervated muscle early as 1week after injury. Therefore, PET could be adopted as a noninvasive imaging modality for acute nerve injuries. In addition, [(18)F]FDG PET may help to understand the role of the nervous system in the control of peripheral tissues.

Diagnostic FDG and FDOPA positron emission tomography scans distinguish the genomic type and treatment outcome of neuroblastoma.

Neuroblastoma (NB) is a heterogeneous childhood cancer that requires multiple imaging modalities for accurate staging and surveillances. This study aims to investigate the utility of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) and 18F-fluoro-dihydroxyphenylalanine (FDOPA) in determining the prognosis of NB. During 2007–2014, forty-two NB patients (male:female, 28:14; median age, 2.0 years) undergoing paired FDG and FDOPA PET scans at diagnosis were evaluated for the maximum standardized uptake value (SUVmax) of FDG or FDOPA by the primary tumor. Patients with older age, advanced stages, or MYCN amplification showed higher FDG and lower FDOPA SUVmax (all P < 0.02). Receiver operating characteristics analysis identified FDG SUVmax≥ 3.31 and FDOPA SUVmax < 4.12 as an ultra-high-risk feature (PET-UHR) that distinguished the most unfavorable genomic types, i.e. segmental chromosomal alterations and/or MYCN amplification, at a sensitivity of 81.3% (54.4%–96.0%) and a specificity of 93.3% (68.1%–99.8%). Considering with age, stage, MYCN status, and anatomical image-defined risk factor, PET-UHR was an independent predictor of inferior event-free survival (multivariate hazard ratio, 4.9 [1.9–30.1]; P = 0.012). Meanwhile, the ratio between FDG and FDOPA SUVmax (G:D) correlated positively with HK2 (Spearman's ρ = 0.86, P < 0.0001) and negatively with DDC (ρ = −0.58, P = 0.02) gene expression levels, which might suggest higher glycolytic activity and less catecholaminergic differentiation in NB tumors taking up higher FDG and lower FDOPA. In conclusion, the intensity of FDG and FDOPA uptake on diagnostic PET scans may predict the tumor behavior and complement the current risk stratification systems of NB.

Multiple nodular lung metastases with no obvious primary showing low positive 18-fluoro deoxyglucose (FDG) uptake on positron emission tomography (PET) scan: A unique case of metastatic ameloblastoma

Abstract Introduction The incidental detection of multiple secondaries in the lung, in an asymptomatic individual calls for detailed evaluation, especially if the 18-fluoro-deoxyglucose positron emission tomography (FDG PET) scan results are inconclusive or unusual. Presentation of case A 45 year old lady, asymptomatic, presented to us for evaluation of incidentally diagnosed, bilateral pulmonary metastases with a provisional diagnoses of advanced lung cancer. FDG PET scanning was inconclusive and revealed low positive FDG uptake. The biopsy revealed it to be metastatic ameloblastoma. She refused surgery but took only one cycle of chemotherapy with paclitaxel and carboplatin, which she then subsequently discontinued but continues to be asymptomatic at last followup. Discussion She gave history of previous ameloblastoma of the left mandible 13 years back, and recurrences 3 and 6 years later, which had been resected. For the last seven years she had no evidence of disease. History of past illness including operative interventions done for apparently benign or locally aggressive lesions of the oral cavity such as an ameloblastoma is important in evaluation of such cases. Conclusion Pulmonary metastases arising from an ameloblastoma maybe associated with low FDG positive uptake, and even though they are rare, it is important to diagnose them, since the prognosis and management of lesions from lung or other primaries and those from ameloblastoma are markedly different.

Long-Term Interrelationship between Brain Metabolism and Amyloid Deposition in Mild Cognitive Impairment.

The aim of this longitudinal positron emission tomography (PET) study was to evaluate the interrelationship between brain metabolism and amyloid accumulation during the disease process from mild cognitive impairment (MCI) to Alzheimer's disease (AD). Nine MCI patients, who converted to AD between two and five years, and nine healthy subjects underwent [11C]PIB and [18F]FDG PET scans at baseline and at 5 years. [11C]PIB uptake was clearly higher in MCI patients at baseline compared to controls and spread extensively to the cerebral cortex during the conversion to AD. [18F]FDG uptake was reduced especially in the temporal-parietal regions in MCI compared to controls at baseline, and widely over the cortex at the 5-year follow-up. The reduction in metabolism during the follow-up was significant in the posterior brain regions. In addition, brain amyloid load was positively associated with metabolism in posterior brain regions in MCI, but not after conversion to AD. The results suggest that there are interactions between brain amyloid accumulation and metabolism during the AD process, including a possible compensatory upregulation of posterior brain metabolism in the early phase.

A contactless approach for respiratory gating in PET using continuous‐wave radar

Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient's torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient's torso. A 24 GHz carrier frequency was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [(18)F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69-0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53-0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin. Accurate respiratory signals were obtained successfully by the proposed method with high spatial and temporal resolution. By working without contact and passing through clothing and blankets, this approach minimizes preparation time and increases the convenience of the patient during the scan.

Paradoxal metabolic flare detected by 18F-fluorodeoxyglucose positron emission tomography in a patient with metastatic breast cancer treated with aromatase inhibitor and biphosphonate

Patients with estrogen-receptor-positive advanced breast cancer are treated with endocrine therapy. The majority of breast cancer localizations show 18F-fluorodeoxyglucose (FDG) uptake at positron emission tomography (PET) examination. In these patients, the metabolic flare after therapy is common and was proposed as an index of therapy efficacy. Nevertheless, prolonged persistence of flare can lead to misinterpretation. We describe a case of a patient with invasive ductal breast cancer with bone metastases at bone scintigraphy and FDG PET scan and with expression of estrogen receptors. Initially, the patient underwent endocrine therapy in addition to a biphosfonate. Owing to progression observed in a bone scan, Tamoxifen was substituted with aromatase inhibitors. Successive bone scan examinations showed stabilization with a marked clinical improvement. A second FDG PET was performed 28 months after the first examination and showed a metabolic flare phenomenon with concomitant partial calcification of osteolitic lesions. This is an unusual case of prolonged metabolic flare.

Erroneous cardiac ECG-gated PET list-mode trigger events can be retrospectively identified and replaced by an offline reprocessing approach: first results in rodents

The assessment of left ventricular function, wall motion and myocardial viability using electrocardiogram (ECG)-gated [18F]-FDG positron emission tomography (PET) is widely accepted in human and in preclinical small animal studies. The nonterminal and noninvasive approach permits repeated in vivo evaluations of the same animal, facilitating the assessment of temporal changes in disease or therapy response. Although well established, gated small animal PET studies can contain erroneous gating information, which may yield to blurred images and false estimation of functional parameters. In this work, we present quantitative and visual quality control (QC) methods to evaluate the accuracy of trigger events in PET list-mode and physiological data. Left ventricular functional analysis is performed to quantify the effect of gating errors on the end-systolic and end-diastolic volumes, and on the ejection fraction (EF). We aim to recover the cardiac functional parameters by the application of the commonly established heart rate filter approach using fixed ranges based on a standardized population. In addition, we propose a fully reprocessing approach which retrospectively replaces the gating information of the PET list-mode file with appropriate list-mode decoding and encoding software. The signal of a simultaneously acquired ECG is processed using standard MATLAB vector functions, which can be individually adapted to reliably detect the R-peaks. Finally, the new trigger events are inserted into the PET list-mode file. A population of 30 mice with various health statuses was analyzed and standard cardiac parameters such as mean heart rate (119 ms ± 11.8 ms) and mean heart rate variability (1.7 ms ± 3.4 ms) derived. These standard parameter ranges were taken into account in the QC methods to select a group of nine optimal gated and a group of eight sub-optimal gated [18F]-FDG PET scans of mice from our archive. From the list-mode files of the optimal gated group, we randomly deleted various fractions (5% to 60%) of contained trigger events to generate a corrupted group. The filter approach was capable to correct the corrupted group and yield functional parameters with no significant difference to the optimal gated group. We successfully demonstrated the potential of the fully reprocessing approach by applying it to the sub-optimal group, where the functional parameters were significantly improved after reprocessing (mean EF from 41% ± 16% to 60% ± 13%). When applied to the optimal gated group the fully reprocessing approach did not alter the functional parameters significantly (mean EF from 64% ± 8% to 64 ± 7%). This work presents methods to determine and quantify erroneous gating in small animal gated [18F]-FDG PET scans. We demonstrate the importance of a quality check for cardiac triggering contained in PET list-mode data and the benefit of optionally reprocessing the fully recorded physiological information to retrospectively modify or fully replace the cardiac triggering in PET list-mode data. We aim to provide a preliminary guideline of how to proceed in the presence of errors and demonstrate that offline reprocessing by filtering erroneous trigger events and retrospective gating by ECG processing is feasible. Future work will focus on the extension by additional QC methods, which may exploit the amplitude of trigger events and ECG signal by means of pattern recognition. Furthermore, we aim to transfer the proposed QC methods and the fully reprocessing approach to human myocardial PET/CT.

Selective Worsening of Brain Injury Biomarker Abnormalities in Cognitively Normal Elderly Persons With β-Amyloidosis

The appearance of β-amyloidosis and brain injury biomarkers in cognitively normal (CN) persons is thought to define risk for the future development of cognitive impairment due to Alzheimer disease (AD), but their interaction is poorly understood. To test the hypothesis that the joint presence of β-amyloidosis and brain injury biomarkers would lead to more rapid neurodegeneration. DESIGN Longitudinal cohort study. Population-based Mayo Clinic Study of Aging. One hundred ninety-one CN persons (median age, 77 years; range, 71-93 years) in the Mayo Clinic Study of Aging who underwent magnetic resonance, fludeoxyglucose F 18 (FDG) positron emission tomography (PET), and Pittsburgh Compound B (PiB) PET imaging at least twice 15 months apart. Participants were grouped according to the recommendations of the National Institute on Aging-Alzheimer Association preclinical AD criteria based on the presence of β-amyloidosis, defined as a PiB PET standardized uptake value ratio (SUVr) greater than 1.5, alone (stage 1) or with brain injury (stage 2 + 3), defined as hippocampal atrophy or FDG hypometabolism. We also studied a group of patients with mild cognitive impairment (n = 17) or dementia (n = 9) from the Mayo Clinic Study of Aging or the Mayo Alzheimer Center with similar follow-up times who had undergone comparable imaging and had a PiB PET SUVr greater than 1.5. Rate of change of cortical volume on volumetric magnetic resonance images and rate of change of glucose metabolism on FDG PET scan results. There were 25 CN participants with both high PiB retention and low hippocampal volume or FDG hypometabolism at baseline (preclinical AD stages 2 + 3). On follow-up scans, the preclinical AD stage 2 + 3 participants had greater loss of medial temporal lobe volume and greater glucose hypometabolism in the medial temporal lobe compared with the other CN groups. The changes were similar to those in the cognitively impaired participants. Extratemporal regions did not show similar changes. Higher rates of medial temporal neurodegeneration occur in CN individuals who, on their initial scans, had abnormal levels of both β-amyloid and brain injury biomarkers. Although preclinical AD is currently only a research topic, the description of its brain structural changes will be critical for trials designed to prevent or forestall dementia due to AD.

Postmortem 3-D Brain Hemisphere Cortical Tau and Amyloid-β Pathology Mapping and Quantification as a Validation Method of Neuropathology Imaging

This work is aimed at correlating pre-mortem [18F]FDDNP positron emission tomography (PET) scan results in a patient with dementia with Lewy bodies (DLB), with cortical neuropathology distribution determined postmortem in three physical dimensions in whole brain coronal sections. Analysis of total amyloid-β (Aβ) distribution in frontal cortex and posterior cingulate gyrus confirmed its statistically significant correlation with cortical [18F]FDDNP PET binding values (distribution volume ratios, DVR) (p < 0.001, R = 0.97, R2 = 0.94). Neurofibrillary tangle (NFT) distribution correlated significantly with cortical [18F]FDDNP PET DVR in the temporal lobe (p < 0.001, R = 0.87, R2 = 0.76). Linear combination of Aβ and NFT densities was highly predictive of [18F]FDDNP PET DVR through all analyzed regions of interest (p < 0.0001, R = 0.92, R2 = 0.85), and both densities contributed significantly to the model. Lewy bodies were present at a much lower level than either Aβ or NFTs and did not significantly contribute to the in vivo signal. [18F]FDG PET scan results in this patient were consistent with the distinctive DLB pattern of hypometabolism. This work offers a mapping brain model applicable to all imaging probes for verification of imaging results with Aβ and/or tau neuropathology brain distribution using immunohistochemistry, fluorescence microscopy, and autoradiography.

The role of 18F-fluorodeoxyglucose positron emission tomography in differentiated thyroid cancer before surgery

The incidence of thyroid cancer in both men and women is increasing faster than that of any other cancer. Although positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) has received much attention, the use of FDG PET for the management of thyroid cancer is limited primarily to postoperative follow-up. However, it might have a role in selected, more aggressive pathologies, and so patients at a high risk of distant metastasis may benefit from PET before surgery. As less FDG-avid thyroid cancers may lower the diagnostic accuracy of PET in preoperative assessment, an understanding of FDG avidity is important for the evaluation of thyroid cancer. FDG avidity has been shown to be associated with tumor size, lymph node metastasis, and glucose transporter expression and differentiation. As PET is commonly used in clinical practice, the detection of incidentalomas by PET is increasing. However, incidentalomas detected by PET have a high risk of malignancy. Clinicians handling cytologically indeterminate nodules face a dilemma regarding a procedure for a definitive diagnosis, usually lobectomy. With 'nondiagnostic (ND)' fine-needle biopsy (FNA), PET has shown a negative predictive value (NPV) of 100%, which indicates that negative uptake in a ND FNA procedure accurately excludes malignancy. With 'atypia of undetermined significance' or 'follicular neoplasm', the sensitivity and NPV of PET are 84 and 88%. PET does not provide additional information for the preoperative assessment of thyroid cancer. However, factors associated with FDG positivity are related to a poor prognosis; therefore, FDG PET scans before surgery may facilitate the prediction of the prognosis of differentiated thyroid cancer.

114IN - Molecular Imaging with Pet/Ct: Fdg and Beyond

ABSTRACT Molecular imaging has rapidly acquired importance for the evaluation of cancer patients, being complementary to conventional imaging methods as CT, MR and US. Among molecular imaging procedures, Positron Emission Tomography (PET) is the most diffuse and rapidly growing, and at present it is routinely used in patients affected by a large variety of malignant neoplastic diseases. Many papers in the literature have already demonstrated the utility of this imaging technique whose capabilities have been furthermore developed by the introduction of hybrid scanners, particularly PET-CT. The combination of functional data (given by PET) and anatomic details (provided by CT) allows to significantly increase diagnostic accuracy, essentially due to a better specificity. The usefulness of PET relies on its capability of investigating molecular processes by means of specific radiotracers, with the most employed being 18F-DeoxyGlucose (FDG). FDG PET scans give important information about tissues glucose consumption, usually very increased in the great majority of solid malignancies. A number of indications for PET use in clinical oncology have already been validated. Main indications are: characterization of uncertain lesions; staging; early evaluation of response to therapy; evaluation of residual disease at therapy completion and identification of relapse during follow-up. Despite FDG scans represent more than 90% of all PET scans, other positron emitter tracers are available and each one may be specific for different neoplastic diseases. In fact some malignancies do not show increase in glucose consumption and are almost invisible with FDG: therefore other tracers have been developed to study other metabolic pathways. Tracers already in clinical use include Choline (labeled with 11C or 18F), a marker of cell membrane metabolism particularly useful for prostate cancer detection; 18F-Tyrosine and 11C-Methionine, which enable to study proteic metabolism and are successfully employed for CNS neoplastic diseases; 18F-DOPA and 68Ga-DOTA-NOC, useful in neuroendocrine tumors. Disclosure The author has declared no conflicts of interest.

Long-term neurotoxic effects of dimethylamine borane intoxication

ObjectivesTo investigate the long-term neurotoxic effects in a patient with acute dimethylamine borane (DMAB) intoxication. PatientsA 38-year-old man, working in a semiconductor factory, with acute DMAB intoxication presented with confusion, and drowsiness, followed by cognitive impairments and motor-predominant axonal polyneuropathy. InvestigationsWe performed serial neurobehavioral assessments and functional neuroimaging studies, including brain 99mTc-TRODAT single photon emission computed tomography (SPECT) and brain positron emission tomography (PET) scan to monitor the long-term central nervous system (CNS) effects of DMAB intoxication. ResultsNeurobehavioral tests revealed a persistent impairment in episodic memory of visual retention semantic category retrieval and working memory of digit span (backward). Brain 99mTc-TRODAT SPECT scan showed a lower radioactivity uptake in the left striatum and F-18 FDG PET scan revealed a relatively decreased cerebral metabolism at the anterior cingulate gyrus and both frontal regions. Follow-up neurobehavioral tests showed that the cognitive improvements were mainly documented in intelligence, attention function, conceptual shift, perceptual motor speed, verbal learning and working memory but were limited in visual memory and executive functions. ConclusionPatients with acute DMAB intoxication may have a long-lasting CNS toxicity on the cognitive dysfunction, parkinsonism, and an impaired metabolic activity of the brain. Clinical improvements may sustain during the long-term follow-up period.

The majority of transformed lymphomas have high standardized uptake values (SUVs) on positron emission tomography (PET) scanning similar to diffuse large B-cell lymphoma (DLBCL)

BackgroundWe previously correlated non-Hodgkin's lymphoma (NHL) histology with 18fluoro-2-deoxyglucose–positron emission tomography (FDG–PET) intensity: a standardized uptake value (SUV) >10 predicted aggressive lymphoma with >80% certainty and an SUV >13, with >90% certainty. Patients and methodsTo evaluate SUV in transformed lymphoma, we identified all FDG–PET scans for NHL at Memorial Sloan-Kettering Cancer 1999–2007 with (i) biopsy-proven transformation, (ii) no therapy 60 days before PET scan and (iii) FDG–PET scans no more than 60 days before or 90 days after transformation. ResultsIn 5 of 40 patients, the biopsy site was excised before PET; in two, only marrow was biopsied. In the remaining 33 patients, the SUV of the biopsy site ranged from 3 to 38, mean 14, median 12. Eighteen of 33 biopsies (55%) had an SUV >10 and 16 (48%) >13. The highest SUV in a transformed lymphoma PET scan (SUVstudy-max) ranged from 3.2 to 40, mean 15, median 12. Twenty-five of 40 patients (63%) presented with an SUVstudy-max >10 and 20 (50%) >13. ConclusionsLike de novo aggressive lymphomas, the majority of transformations have a high SUVstudy-max for a given pretreatment staging study, although many do not have very high values. Transformation should be suspected in indolent lymphoma with high SUVs on FDG–PET. Biopsies should be directed to the site of greatest FDG avidity.

Dyspnea on Exertion and Ground-Glass Infiltrates in an Ex-Smoker

Dyspnea on Exertion and Ground-Glass Infiltrates in an Ex-Smoker

Diagnosis of prostatitis by 18-F-fluorodeoxyglucose positron emission tomography.

A 74-year-old man, who underwent renal transplantation in April 2007 for end-stage renal failure caused by chronic glomerulonephritis, was admitted in August 2008 for fever (38.5°C) without orientation symptoms. He had history of essential hypertension, diabetes and ischaemic cardiopathy. The patient had presented two episodes of isolated fever in June 2007, with negative bacteriology, which responded to large spectrum antibiotics. He reported cloudy urines, but no mictalgia nor pelvic pain. Physical examination was unremarkable, and the renal transplant was not painful. Initial blood tests showed a high C-reactive protein (33 mg/dL), a white blood cell count of 18 000/μL (85% neutrophils) and a mild increase in plasma creatinine (1.6 mg/dL). There was no leucocyturia, but urine culture was positive for Enterococcus faecalis. The prostate-specific antigen (PSA) was normal at 0.14 ng/mL. Eight blood culture pairs remained sterile. Renal ultrasonography was unremarkable. An 18-F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scan revealed an intense prostatic fixation, compatible with prostate abscess (Figure ​(Figure1).1). The diagnosis was confirmed by painful digital rectal examination. Appropriate antibiotherapy was initiated, resulting in the disparition of fever and normalization of inflammation and renal function. Fig. 1 Coronal (A, C) and axial (B) sections of FDG PET (A) and FDG PET scan (B, C) showing the intense FDG uptake in the prostate (arrow), in addition to the normal captation in the brain and urinary bladder. The image indicates the presence of a prostate abscess, ... The association between fever and bacteriuria in a renal transplant recipient can be caused by transplant pyelonephritis or prostatitis. The diagnosis of prostatitis may be difficult in the absence of specific symptoms or with normal PSA levels [1,2] causing delay in treatment. In our patient, the PET scan focused intensely on the prostate, leading to the diagnosis of prostatitis despite normal PSA level. This case, the first documented in a renal transplant recipient, confirms the value of 18-FDG PET scan in a fever of unknown origin and, more precisely, in the diagnosis of bacterial prostatitis. The differential diagnosis of increased FDG uptake in the prostate includes inflammatory and malignant processes [3]. Conflict of interest statement. None declared.

Results of 188 Whole-Body Fluorodeoxyglucose Positron Emission Tomography Scans in 137 Patients With Sarcoidosis

To study the role of whole-body 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans in the identification of occult biopsy sites and reversible granulomatous disease in patients with sarcoidosis. A retrospective review was undertaken of 188 FDG PET scans performed in 137 patients with proven sarcoidosis. All patients had given a complete medical history and undergone a physical examination, standard chest radiograph, spirometry, diffusing capacity determination, and measurement of serum angiotensin-converting enzymes levels. One hundred thirty-nine whole-body scans had positive findings. The most common positive sites were mediastinal lymph nodes (54 scans), extrathoracic lymph nodes (30 scans), and lung (24 scans). The standardized uptake value (SUV) ranged from 2.0 to 15.8. Twenty occult disease sites were identified. Eleven repeat scans exhibited decreased SUV with corticosteroid therapy. The positive pulmonary FDG PET scan findings occurred in two thirds of patients with radiographic stage II and III sarcoidosis. Negative pulmonary FDG PET scan findings were common in patients with radiographic stage 0, I, and IV sarcoidosis. Whole-body FDG PET scans are of value in identifying occult and reversible granulomas in patients with sarcoidosis. However, a positive FDG PET scan finding, by itself, is not an indication for treatment.

Positron Emission Tomography Detection of Distant Metastatic or Synchronous Disease in Patients with Locally Advanced Rectal Cancer Receiving Preoperative Chemoradiation

Patients with locally advanced rectal cancer may present with synchronous distant metastases. Choice of optimal treatment--neoadjuvant chemoradiation versus systemic chemotherapy alone--depends on accurate assessment of distant disease. We prospectively evaluated the ability of [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) to detect distant disease in patients with locally advanced rectal cancer who were otherwise eligible for combined modality therapy (CMT). Ninety-three patients with locally advanced rectal cancer underwent whole-body [18F]FDG PET scanning 2-3 weeks before starting CMT. Sites other than the rectum, mesorectum, or the area along the inferior mesenteric artery were considered distant and were divided into nine groups: neck, lung, mediastinal lymph node (LN), abdomen, liver, colon, pelvis, peripheral LN, and soft tissue. Two nuclear medicine physicians blinded to clinical information used PET images and a five-point scale (0-4) to determine certainty of disease. A score greater than 3 was considered malignant. Confirmation was based on tissue diagnosis, surgical exploration, and subsequent imaging. At a median follow-up of 34 months, the overall accuracy, sensitivity, and specificity of PET in detecting distant disease were 93.7%, 77.8%, and 98.7% respectively. Greatest accuracy was demonstrated in detection of liver (accuracy = 99.9%, sensitivity = 100%, specificity = 98.8%) and lung (accuracy = 99.9%, sensitivity = 80%, specificity = 100%) disease; PET detected 11/12 confirmed malignant sites in liver and lung. A total of 10 patients were confirmed to have M1 stage disease. All 10 were correctly staged by pre-CMT PET; abdominopelvic computed tomography (CT) scans accurately detected nine of them. Baseline PET in patients with locally advanced rectal cancer reliably detects metastatic disease in liver and lung. PET may play a significant role in defining extent of distant disease in selected cases, thus impacting the choice of neoadjuvant therapy.

Serial Multimodality Assessment of Myocardial Infarction in Mice Using Magnetic Resonance Imaging and Micro–Positron Emission Tomography Provides Complementary Information on the Progression of Scar Formation

Recent technological advances have made imaging the mouse heart possible using both 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI),1–4 thus facilitating the investigation of mechanisms underlying the progression toward heart failure after myocardial infarction (MI). These imaging modalities provide complementary information regarding cellular metabolism and infarct location, respectively. To demonstrate this, we used FDG PET and MRI in a serial study of male C57Bl/6 mice that were subjected to a 1-hour coronary occlusion and then 30 days of reperfusion. Imaging was performed 1, 7, and 28 days after coronary occlusion. Gd-enhanced ECG-gated cardiac MRI was performed using a 4.7-T MRI scanner (Varian, Inc, …

Comparison between Microvascular Integrity Indexes Assessed by Pressure/Doppler Wire and %FDG Uptake in AMI following Primary PCI

Background and Objectives：Microvascular integrity has been associated with the clinical outcomes in acute myocardial infarction (AMI). The present study was conducted to determine the value of many microvascular indexes assessed by an intracoronary (IC) pressure/Doppler wire in AMI following primary PCI for detecting viable myocardium by comparing with the 18 F-fluorodeoxyglucose uptake rate (%FDG uptake) on positron-emission tomography (PET). Subjects and Methods：We studied 35 patients who had their first AMI (age: 56± 12, male: 30). After primary PCI, the TMPG (TIMI myocardial perfusion grade) was assessed. We measured the coronary flow reserve (CFR), the diastolic deceleration time (DDT), the coronary wedge pressure (Pcw), the Pcw/ Pa (mean aortic pressure) and the hyperemic microvascular resistance index (hMVRI) by an IC Doppler/ pressure wire. 18 FDG PET scan was obtained at 7 days after the primary PCI; viable myocardium was defined that the %FDG uptake was more than 50% in infarct-related myocardium. Results：There were significant correlations between TMPG, CFR, Pcw, Pcw/Pa, DDT, hMVRI and %FDG uptake (r=0.651, p<0.001; r=0.386, p=0.020; r=-0.388, p=0.021; r=-0.473, p=0.004; r=0.589, p<0.001; r=-0.442, p=0.008, respectively). The best cutoff values and area under curves (AUC) of the CFR, Pcw, Pcw/Pa, DDT and hMVRI for 50% FDG uptake were 1.8 (0.737), 27 mmHg (0.600), 0.33 (0.660), 600 msec (0.802) and 2.55 mmHg·cm -1 ·sec (0.768), respectively. The DDT had a significantly higher AUC than that of Pcw (p=0.029) and it was an independent index to predict the myocardial viability (p=0.011). Conclusion：DDT was the most reliable hemodynamic microvascular index that was assessed within 24 hours following primary PCI for predicting the viable myocardium in AMI patients. (Korean Circulation J 2006;36:701-709)

Preliminary findings of uncoupling of flow and metabolism in unipolar compared with bipolar affective illness and normal controls

Cerebral metabolism (CMR for glucose or oxygen) and blood flow (CBF) have been reported to be closely correlated in healthy controls. Altered relationships between CMR and CBF have been reported in some brain disease states, but not others. This study examined relationships between global and regional CMRglu vs. CBF in controls and medication-free primary affective disorder patients. Nine bipolars, eight unipolars, and nine healthy controls had [ 15O]-water positron emission tomography (PET) scans at rest, and [ 18F]-fluorodeoxyglucose PET scans during an auditory continuous performance task. Patients had [ 15O]-water and FDG PET scans in tandem the same day; controls had an average of 45 ± 27 days between scans. Maps of regional coupling were constructed for each subject group. In controls and bipolars, global and virtually all regional correlation coefficients for CMRglu and CBF were positive, albeit more robustly so in controls. However, correlative relationships in unipolars were qualitatively different, such that global and most regional measures of flow and metabolism were not positively related. Unipolars had significantly fewer positive regional correlation coefficients than healthy controls and bipolars. These were significantly different from controls in orbital cortex, anterior cingulate, posterior cingulate, and posterior temporal cortex, and different from bipolars in pregenual anterior cingulate. In unipolars, the degree of flow–metabolism uncoupling was inversely correlated with Hamilton depression scores, indicating the severity of uncoupling was directly related to the severity of depression. These preliminary data suggest abnormal relationships between cerebral metabolism and blood flow globally and regionally in patients with unipolar depression that warrant replication and extension to potential pathophysiological implications.