18F-FDG PET Scans Research Articles

Silent Brain Abnormalities in Thalassemia Intermedia: A Combined MRI/PET Study.

Abstract 4077Poster Board III-1012 IntroductionPatients with thalassemia intermedia (TI) have an increased risk of thrombosis compared with thalassemia major patients. Thromboembolic events are more frequently observed in older TI patients (>20 yrs) who are splenectomized and non-transfused. Brain involvement has not been widely studied; however, one study has documented silent strokes on brain MRI in 37% of patients, indicating that further investigation is warranted. Patients and methodsThis was a cross-sectional study on 30 TI patients >18 years of age, splenectomized, not receiving regular transfusion therapy, and receiving no antiplatelet or anticoagulant medication. Patients were initially screened to establish absence of neurological signs or symptoms and other stroke-related disease (diabetes, hypertension, carotid stenosis, cardiac disease or prothrombotic mutations). All patients underwent both MRI and 18F-FDG PET scan on the same day. The criterion for abnormality on PET was the decrease in neuronal function (glucose utilization). MRIs were performed using T1- and T2- weighted spin-echo techniques. Abnormality was defined as an area of abnormally increased signal intensity on the T2-weighted pulse sequences. ResultsThe mean age was 31.9 yrs (range: 18–54 yrs) with a male to female ratio of 13:17. Among the group of 30 subjects, 18 (60%) had abnormal MRI findings, 19 (63.3%) had abnormal PET findings, and 26 (86.7%) had either an abnormal MRI or abnormal PET or both. Solitary findings were identified in 7 (26.9%) of patients while multiple lesions were observed in 19 (73.1%) of patients who had abnormality. Bilateral findings were documented in 14 (53.8%) of patients with abnormality. The most common regions of abnormality were the parietal (76.9%) and frontal (69.2%) lobes; followed by the temporal (53.8%) and occipital (15.4%) lobes. ConclusionsMRI/PET evaluation has demonstrated that silent brain abnormality is a common finding in this population of adult, splenectomized, non-regularly-transfused TI patients. Disclosures:Taher:Novartis: Honoraria, Research Funding.

18F-FDG PET as a Routine Posttreatment Surveillance Tool in Oral and Oropharyngeal Squamous Cell Carcinoma: A ProspectiveStudy

The purpose of this study was to evaluate the role and timing of serial (18)F-FDG PET scans as routine surveillance for detecting early locoregional recurrence, distant metastases, and second primary tumors in patients treated for advanced squamous cell carcinoma (SCC) in the oral cavity or oropharynx during the first year after completion of their curative treatment. Forty-eight consecutive patients with SCC in the oral cavity or oropharynx were included after completing their initial therapy with curative intent. Prospective follow-up of the participants was 2-fold: regular follow-up (history and physical examination) and serial (18)F-FDG PET scans. Patients underwent standard follow-up and (18)F-FDG PET at 3, 6, 9, and 12 mo after initial treatment. Findings were validated by histopathology or 18 mo of clinical follow-up and imaging after initial treatment. Incidence of recurrences and second primary tumors was 27% and 10%, respectively. (18)F-FDG PET was significantly (P = 0.035) more often in agreement with the gold standard than was regular follow-up. (18)F-FDG PET showed a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 43%, 51%, and 100%, respectively. For regular follow-up, these values were 0%, 60%, 0%, and 50%, respectively. (18)F-FDG PET accounted for a change in diagnostics or treatment in 63% of the patients and regular follow-up in 25% of the patients. Sensitivity and specificity of (18)F-FDG PET were both irrespective of timing of (18)F-FDG PET. For the 3- and 6-mo posttherapy results combined, (18)F-FDG PET detected malignancy in 16 of the 18 patients. (18)F-FDG PET is a suitable routine posttreatment surveillance tool in oral and oropharyngeal SCC patients and detects malignancy before clinical suggestion by the regular follow-up arises. The best timing of a systematic (18)F-FDG PET scan is between 3 and 6 mo after treatment.

A Curve-Fitting Approach to Estimate the Arterial Plasma Input Function for the Assessment of Glucose Metabolic Rate and Response to Treatment

For the quantification of dynamic (18)F-FDG PET studies, the arterial plasma time-activity concentration curve (APTAC) needs to be available. This can be obtained using serial sampling of arterial blood or an image-derived input function (IDIF). Arterial sampling is invasive and often not feasible in practice; IDIFs are biased because of partial-volume effects and cannot be used when no large arterial blood pool is in the field of view. We propose a mathematic function, consisting of an initial linear rising activity concentration followed by a triexponential decay, to describe the APTAC. This function was fitted to 80 oncologic patients and verified for 40 different oncologic patients by area-under-the-curve (AUC) comparison, Patlak glucose metabolic rate (MR(glc)) estimation, and therapy response monitoring (Delta MR(glc)). The proposed function was compared with the gold standard (serial arterial sampling) and the IDIF. To determine the free parameters of the function, plasma time-activity curves based on arterial samples in 80 patients were fitted after normalization for administered activity (AA) and initial distribution volume (iDV) of (18)F-FDG. The medians of these free parameters were used for the model. In 40 other patients (20 baseline and 20 follow-up dynamic (18)F-FDG PET scans), this model was validated. The population-based curve, individually calibrated by AA and iDV (APTAC(AA/iDV)), by 1 late arterial sample (APTAC(1 sample)), and by the individual IDIF (APTAC(IDIF)), was compared with the gold standard of serial arterial sampling (APTAC(sampled)) using the AUC. Additionally, these 3 methods of APTAC determination were evaluated with Patlak MR(glc) estimation and with Delta MR(glc) for therapy effects using serial sampling as the gold standard. Excellent individual fits to the function were derived with significantly different decay constants (P < 0.001). Correlations between AUC from APTAC(AA/iDV), APTAC(1 sample), and APTAC(IDIF) with the gold standard (APTAC(sampled)) were 0.880, 0.994, and 0.856, respectively. For MR(glc), these correlations were 0.963, 0.994, and 0.966, respectively. In response monitoring, these correlations were 0.947, 0.982, and 0.949, respectively. Additional scaling by 1 late arterial sample showed a significant improvement (P < 0.001). The fitted input function calibrated for AA and iDV performed similarly to IDIF. Performance improved significantly using 1 late arterial sample. The proposed model can be used when an IDIF is not available or when serial arterial sampling is not feasible.

Repeatability of 18F-FDG PET in a Multicenter Phase I Study of Patients with Advanced Gastrointestinal Malignancies

(18)F-FDG PET is often used to monitor tumor response in multicenter oncology clinical trials. This study assessed the repeatability of several semiquantitative standardized uptake values (mean SUV [SUV(mean)], maximum SUV [SUV(max)], peak SUV [SUV(peak)], and the 3-dimensional isocontour at 70% of the maximum pixel value [SUV(70%)]) as measured by repeated baseline (18)F-FDG PET studies in a multicenter phase I oncology trial. Double-baseline (18)F-FDG PET studies were acquired for 62 sequentially enrolled patients. Tumor metabolic activity was assessed by SUV(mean), SUV(max), SUV(peak), and SUV(70%). The effect on SUV repeatability of compliance with recommended image-acquisition guidelines and quality assurance (QA) standards was assessed. Summary statistics for absolute differences relative to the average of baseline values and repeatability analysis were performed for all patients and for a subgroup that passed QA, in both a multi- and a single-observer setting. Intrasubject precision of baseline measurements was assessed by repeatability coefficients, intrasubject coefficients of variation (CV), and confidence intervals on mean baseline differences for all SUV parameters. The mean differences between the 2 SUV baseline measurements were small, varying from -2.1% to 1.9%, and the 95% confidence intervals for these mean differences had a maximum half-width of about 5.6% across the SUV parameters assessed. For SUV(max), the intrasubject CV varied from 10.7% to 12.8% for the QA multi- and single-observer datasets and was 16% for the full dataset. The 95% repeatability coefficients ranged from -28.4% to 39.6% for the QA datasets and up to -34.3% to 52.3% for the full dataset. Repeatability results of double-baseline (18)F-FDG PET scans were similar for all SUV parameters assessed, for both the full and the QA datasets, in both the multi- and the single-observer settings. Centralized quality assurance and analysis of data improved intrasubject CV from 15.9% to 10.7% for averaged SUV(max). Thresholds for metabolic response in the multicenter multiobserver non-QA settings were -34% and 52% and in the range of -26% to 39% with centralized QA. These results support the use of (18)F-FDG PET for tumor assessment in multicenter oncology clinical trials.

Prediction Model of Chemotherapy Response in Osteosarcoma by 18F-FDG PET and MRI

Response to neoadjuvant chemotherapy is a significant prognostic factor for osteosarcoma; however, this information can be determined only after surgical resection. If we could predict histologic response before surgery, it might be helpful for the planning of surgeries and tailoring of treatment. We evaluated the usefulness of (18)F-FDG PET for this purpose. A total of 70 consecutive patients with a high-grade osteosarcoma treated at our institute were prospectively enrolled. All patients underwent (18)F-FDG PET and MRI before and after neoadjuvant chemotherapy. We analyzed the predictive values of 5 parameters, namely, maximum standardized uptake values (SUVs), before and after (SUV2) chemotherapy, SUV change ratio, tumor volume change ratio, and metabolic volume change ratio (MVCR) in terms of their abilities to discriminate responders from nonresponders. Patients with an SUV2 of less than or equal to 2 showed a good histologic response, and patients with an SUV2 of greater than 5 showed a poor histologic response. The histologic response of a patient with an intermediate SUV2 (2 < SUV2 </= 5) was found to be predictable using MVCR. A patient with an MVCR of less than 0.65 is likely to be a good responder, whereas a patient with an MVCR of greater than or equal to 0.65 is likely to be a poor responder. According to our model, the predictive values for good responders and poor responders were 97% (31/32) and 95% (36/38), respectively. We found that combined information on (18)F-FDG PET and MRI scans, acquired before and after chemotherapy, could be used to predict histologic response to neoadjuvant chemotherapy in osteosarcoma.

18F-FDG PET SUVmax Correlates with Osteosarcoma Histologic Response to Neoadjuvant Chemotherapy: Preclinical Evaluation in an Orthotopic Rat Model

Assessment of osteosarcoma response to neoadjuvant chemotherapy is performed by histopathologic analysis after surgical resection of the primary tumor. The purpose of this study was to evaluate whether (18)F-FDG PET could be a noninvasive surrogate to histopathologic analysis and allow for earlier response evaluation to neoadjuvant chemotherapy in osteosarcoma. Metabolic response to neoadjuvant chemotherapy was assessed in immunocompetent rats with a preestablished orthotopic osteosarcoma using (18)F-FDG PET before and after receiving 2 doses of ifosfamide. Comparison was then made by assessing histologic responses on euthanized animals. Maximum standardized uptake value (SUVmax) measured by (18)F-FDG PET after 2 doses of chemotherapy was correlated to histologic classification (P < 0.01). An SUVmax less than 15 corresponded to good responders, whereas an SUVmax greater than 15 but less than 20 and an SUVmax greater than 20 corresponded to partial responders or nonresponders, respectively. A 40% decrease in SUVmax between the first and second (18)F-FDG PET scans distinguished between partial and good response to chemotherapy. Determination of SUVmax using semiquantitative (18)F-FDG PET predicts response to neoadjuvant chemotherapy earlier than does histologic analysis.

Altered Brain Serotonin Transporter and Associated Glucose Metabolism in Alzheimer Disease

Whether preclinical depression is one of the pathophysiologic features of Alzheimer disease (AD) has been under debate. In vivo molecular imaging helps clarify this kind of issue. Here, we examined in vivo changes in the brain serotoninergic system and glucose metabolism by scanning early- to moderate-stage AD patients with and without depression using PET with a radiotracer for the serotonin transporter, (11)C-3-amino-4-(2-dimethylaminomethylphenylsulfanyl) benzonitrile (DASB), and a metabolic marker, (18)F-FDG. Fifteen AD patients (8 nondepressed and 7 depressed) and 10 healthy subjects participated. All participants underwent 3-dimensional MRI and quantitative (11)C-DASB PET measurements, followed by (18)F-FDG PET scans in the AD group. Region-of-interest analysis was used to examine changes in (11)C-DASB binding potential estimated quantitatively by the Logan plot method in the serotonergic projection region. In addition, statistical parametric mapping was used to examine whether glucose metabolism in any brain region correlated with levels of (11)C-DASB binding in the dense serotonergic projection region (striatum) in AD. Psychologic evaluation showed that general cognitive function (Mini-Mental State Examination) was similar between the 2 AD subgroups. Striatal (11)C-DASB binding was significantly lower in AD patients, irrespective of depression, than in healthy controls (P < 0.05, corrected), and (11)C-DASB binding in other dense projection areas decreased significantly in the depressive group, compared with the control group. The (11)C-DASB binding potential levels in the subcortical serotonergic projection region correlated negatively with depression score (Spearman correlation, P < 0.01) but not with dementia score. Statistical parametric mapping correlation analysis showed that glucose metabolism in the right dorsolateral prefrontal cortex was positively associated with the level of striatal (11)C-DASB binding in AD. The significant reduction in (11)C-DASB binding in nondepressed AD patients suggests that presynaptic serotonergic function is altered before the development of psychiatric problems such as depression in AD. The depressive AD group showed greater and broader reductions in binding, suggesting that a greater loss of serotonergic function relates to more severe psychiatric symptoms in the disease. This serotonergic dysfunction may affect the activity of the right dorsolateral prefrontal cortex, a higher center of cognition and emotion in AD.

123I-MIBG Scintigraphy and 18F-FDG PET in Neuroblastoma

The purpose of this study was to compare the diagnostic utility of (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy and (18)F-FDG PET in neuroblastoma. A total of 113 paired (123)I-MIBG and (18)F-FDG PET scans in 60 patients with neuroblastoma were retrospectively reviewed. Paired scans were acquired within 14 days of each other. For stage 1 and 2 neuroblastoma (13 scans, 10 patients), (18)F-FDG depicted more extensive primary or residual neuroblastoma in 9 of 13 scans. (123)I-MIBG and (18)F-FDG showed equal numbers of lesions in 1 of 13 scans, and 3 of 13 scan results were normal. For stage 3 neuroblastoma (15 scans, 10 patients), (123)I-MIBG depicted more extensive primary neuroblastoma or local or regional metastases in 5 of 15 scans. (18)F-FDG depicted more extensive primary neuroblastoma or local or regional metastases in 4 of 15 scans. (123)I-MIBG and (18)F-FDG were equal in 2 of 15 scans, and 4 of 15 scan results were normal. For stage 4 neuroblastoma (85 scans, 40 patients), (123)I-MIBG depicted more neuroblastoma sites in 44 of 85 scans. (18)F-FDG depicted more neuroblastoma sites in 11 of 85 scans. (123)I-MIBG and (18)F-FDG were equivalent or complementary in 13 of 85 scans, and 17 of 85 scan results were normal. (18)F-FDG is superior in depicting stage 1 and 2 neuroblastoma, although (123)I-MIBG may be needed to exclude higher-stage disease. (18)F-FDG also provides important information for patients with tumors that weakly accumulate (123)I-MIBG and at major decision points during therapy (i.e., before stem cell transplantation or before surgery). (18)F-FDG can also better delineate disease extent in the chest, abdomen, and pelvis. (123)I-MIBG is overall superior in the evaluation of stage 4 neuroblastoma, especially during initial chemotherapy, primarily because of the better detection of bone or marrow metastases.

Influence of N-butylscopolamine on SUV in FDG PET of the bowel

Peristalsis can lead to confusing FDG PET bowel uptake artefacts and potential for recording inaccurate mean standardised uptake value (SUV) measurements in PET-CT scans. Accordingly, we investigate the influence of different SUV normalisations on FDG PET uptake of the bowel and assess which one(s) have least dependence on body size factors in patients with and without the introduction of the anti-peristalsis agent N-butylscopolamine (Buscopan). This study consisted of 92 prospective oncology patients, each having a whole body (18)F-FDG PET scan. Correlations were investigated between height, weight, glucose, body mass index (bmi), lean body mass (lbm) and body surface area (bsa) with maximum and mean SUV recorded for bowel normalised to weight (SUV(w)), lbm (SUV(lbm)), bsa (SUV(bsa)) and blood glucose corrected versions (SUV(wg), SUV(lbmg), SUV(bsag)). Standardised uptake value normalisations were significantly different between control and Buscopan groups with less variability experienced within individual SUV normalisations by the administration of Buscopan. Mean SUV normalisations accounted for 80% of correlations in the control group and 100% in the Buscopan group. Further, >86% of all correlations across both groups were dominated by mean SUV normalisations of which, about 69% were accounted for by SUV(bsa) and SUV(bsag). We recommend avoiding mean SUV(bsa) and individual glucose normalisations especially, mean SUV(bsag) as these dominated albeit relatively weak correlations with body size factors in control and Buscopan groups. Mean and maximum SUV(w) and SUV(lbm) were shown to be independent of any body size parameters investigated in both groups and therefore considered suitable for monitoring FDG PET uptake in the normal bowel for our patient cohort.

Brain Metabolic Correlates of Cerebrospinal Fluid Beta-Amyloid 42 and Tau in Alzheimer’s Disease

Background: The cerebrospinal fluid (CSF) proteins β-amyloid 42 (Aβ42) and Tau are believed to indirectly reflect some core pathological features of Alzheimer’s disease (AD). Their topographic origin and their association with synaptic dysfunction are still not well understood. Aim: The present study aimed to explore possible associations between cerebral glucose metabolism and CSF Aβ42 as well as Tau protein levels in AD. Methods: CSF analyses and ¹⁸F-FDG PET scans were conducted on 32 patients with mild-to-moderate AD. Voxel-based statistical parametric correlations were computed for CSF protein levels and cerebral glucose metabolism. Results: After correction for multiple comparisons, a strong positive association between CSF Aβ42 levels and glucose metabolism was identified for 2 extensive clusters located in the right temporal, prefrontal and anterior cingulate cortices. For CSF Tau protein, no association was observed for any brain region. Conclusions: These findings point to a significant association between synaptic dysfunction as measured with ¹⁸F-FDG PET and CSF Aβ42 levels, but do not suggest a correlation between synaptic function and CSF Tau levels.

Pituitary Adenomas Can Appear as Hypermetabolic Lesions in 18F‐FDG PET Imaging

The 2-deoxy-2-[(18) F] fluoro-D-glucose positron emission tomography (FDG-PET) scan is commonly used in detection and staging of many malignant neoplasms. However, several benign or non-neoplastic conditions avidly accumulate (18) F-FDG, causing ambiguity in interpretation of results. It is unknown whether pituitary adenomas uptake (18) F-FDG and appear positive in PET imaging. Here, we present 2 cases of benign pituitary adenoma with elevated metabolic activity in (18) F-FDG PET scan. Medical, neurologic, and psychiatric histories; physical examination findings; laboratory work up results; and pathologic and imaging studies were documented. The (18) F-FDG-PET images revealed foci of marked FDG uptake in pituitary adenomas of 2 patients. Pituitary micro- and macro-adenomas may present as hypermetabolic foci on (18) F-FDG PET scan.

Real pirates any day

Hürthle cell carcinoma is an uncommon differentiated thyroid cancer characterized by an aggressive clinical course and low avidity for ¹³¹I. Treatment usually involves an aggressive surgical approach often combined with ¹³¹I. ¹⁸F-FDG PET has been helpful in the staging and evaluation of many types of aggressive malignancy. No reports to date have described the utility of PET in a series of patients with Hürthle cell cancer. We reviewed our experience with ¹⁸F-FDG PET in the care of patients with Hürthle cell carcinoma to determine the likelihood of uptake in these cancers and the effect of ¹⁸F-FDG PET on patient care. <b>Methods:</b> Patients with Hürthle cell cancer who were seen between June 2000 and April 2002 and were imaged with ¹⁸F-FDG PET were included. Imaging and clinical data were reviewed. PET results were compared with the results of anatomic imaging (CT, sonography, or MRI) and ¹³¹I imaging when performed. Patient charts were reviewed to identify any change in management that resulted from the ¹⁸F-FDG PET findings. <b>Results:</b> Fourteen ¹⁸F-FDG PET scans of 12 patients were obtained in the time frame indicated. All patients had documented Hürthle cell carcinoma. PET showed intense ¹⁸F-FDG uptake in all known Hürthle cell cancer lesions but one. PET showed disease not identified by other imaging methods in 7 of the 14 PET scans. PET identified distant metastatic disease (5) or local disease (2) that was more extensive than otherwise demonstrated. In 7 of the 14 scans, the information provided by PET was used to guide or change therapy. <b>Conclusion:</b> Hürthle cell carcinoma demonstrates intense uptake on ¹⁸F-FDG PET images. PET improves disease detection and disease management in patients with Hürthle cell carcinoma relative to anatomic or iodine imaging. ¹⁸F-FDG PET should be recommended for the evaluation and clinical management of patients with Hürthle cell carcinoma.

Effect of Long-Term Homocysteine Reduction with B Vitamins on Arterial Wall Inflammation Assessed by Fluorodeoxyglucose Positron Emission Tomography: A Randomised Double-Blind, Placebo-Controlled Trial

Background: Homocysteine may promote atherosclerosis by exacerbating inflammatory processes within the arterial wall. B-vitamin supplements reduce total plasma homocysteine concentrations (tHcy), but it is not known whether the treatment also reduces arterial wall inflammation. We used ¹⁸F-fluorodeoxygluose positron emission tomography (¹⁸F-FDG PET) to investigate whether long-term homocysteine-lowering treatment alters arterial wall inflammation in patients with a history of ischemic stroke. Methods: 30 stroke patients were randomly assigned to B-vitamin therapy (folic acid 2 mg, vitamin B₆ 25 mg and vitamin B₁₂ 0.5 mg) or placebo in a double-blind clinical trial. After a mean treatment period of 4.0 ± 0.7 years, all subjects had tHcy, carotid intima-medial thickness (CIMT) and flow-mediated dilation (FMD) of the brachial artery measured and underwent an ¹⁸F-FDG PET scan. Standardised uptake values (SUV) were measured at six sites in the carotid, femoral and aortic arteries. Areas of locally increased tracer uptake in the arterial wall (‘hot spots’) were also identified and counted. Results: Long-term B-vitamin treatment significantly reduced tHcy compared with placebo (8.4 μmol/l, 95% confidence interval, CI, 7.2–9.6 vs. 11.6 μmol/l, 95% CI 10.0–13.4, p = 0.002). The treatment did not affect mean arterial SUV (2.0 ± 0.3 vitamins vs. 2.1 ± 0.3 placebo, p = 0.65) or the number of hot spots (n = 1.1 ± 1.0 vitamins vs. n = 1.2 ± 1.0 placebo, p = 0.65). There was no significant correlation between mean arterial SUV and CIMT or FMD. Conclusions: These results suggest that a long-term Hcy reduction with B vitamins does not affect arterial wall inflammation assessed by ¹⁸F-FDG PET.

PET and Macro- and Microautoradiographic Studies Combined with Immunohistochemistry for Monitoring Rat Intestinal Ulceration and Healing Processes

18F-FDG PET is used mainly in clinical settings for imaging focal cancer sites, but the usefulness of the modality in imaging gastrointestinal ulcers has not been established. We investigated whether PET can be used for noninvasive monitoring of indomethacin-induced small-intestine ulceration. Intestinal ulcers were induced in rats by subcutaneous administration of indomethacin. An 18F-FDG PET scan was obtained at 1, 2, and 7 d after indomethacin administration. 18F-FDG uptake in the small intestine was quantified by gamma-counting, and macro- and microautoradiographic studies were performed to determine the site of 18F-FDG uptake in tissue and at the cellular level. Ulcers observed in the intestine (mainly in the ileum) 1-4 d after indomethacin administration were most severe at 1 d after administration and were almost healed at day 7. The PET study showed increased 18F-FDG uptake in the intestine correlating to the severity of ulceration, returning to the basal level on day 7. Ex vivo imaging and gamma-counting showed that these regions of high uptake corresponded to regions of ulceration. A microautoradiographic study combined with immunohistochemistry revealed heavy accumulation of 18F-FDG in inflammatory cells containing peroxidase on day 1 and in cells forming granulation tissue (alpha-smooth muscle actin-positive myofibroblasts and ED2-positive macrophages) on days 2-4 in and around ulcers. Proliferating (Ki67-immunopositive) intestinal crypt cells were also densely labeled with 18F-FDG in intact intestinal tissue taken from the indomethacin-treated and the control animals. Our experimental data suggest that 18F-FDG PET may be useful for evaluating the occurrence of small-intestine ulcers. Ulceration could be visualized early by the prominent uptake of 18F-FDG by inflammatory cells and by the formation of granulation tissue by cells in and around ulcers.

Fluorodeoxyglucose Positron Emission Tomography for the Diagnosis of Sarcoidosis in Patients with Unexplained Chronic Uveitis

Purpose: To assess the value of fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) in patients with unexplained chronic uveitis. Methods: Retrospective review of 19 18F-FDG PET scans. All patients had normal chest CT. In the final analysis, the authors used criteria similar to the criteria of Abad et al. (Abad S, Meyssonier V, Allali J, et al. Association of peripheral multifocal choroiditis with sarcoidosis: a study of thirty-seven patients. Arthritis Rheum. 2004;51:974–982) for the diagnosis of sarcoidosis-associated uveitis. Results: Ten (53%) whole-body scans were consistent with sarcoidosis. At the end, subsequent mediastinal biopsies proved sarcoidosis in 3 patients; 2 patients were considered as presumed sarcoidosis, and 6 indeterminate sarcoidosis. Conclusion: 18F-FDG PET may show focal uptake suggestive of sarcoidosis in patients with unexplained uveitis.

Negative predictive value of F-18-FDG coincidence PET in patients with Hodgkin's disease and a residual mass after therapy: a retrospective diagnostic test study

Background. The aim of the study was to asses the negative predictive value (NPV) of FDG-PET performed with triple-head coincidence gamma camera after the first-line therapy or salvage therapy in patients with Hodgkin’s disease (HD) compared by a long-term follow-up as a reference standard. Methods. This retrospective diagnostic test study was done at the University Hospital Centre Zagreb between June 2001 and February 2008. The charts of 131 consecutive patients with Hodgkin’s disease were reviewed. Seventy-three consecutive PET-negative patients (median age 28 years; range 12-80 years) with primary or recurrent biopsy confirmed lymphoma after the first-line therapy or salvage therapy were followed-up at least 12 months (median 23 months; range 12-69 months). All already performed 18F-FDG PET scans (using hybrid PET camera with triple head coincidence imaging capability within a few months after the completion of the therapy) were again visually interpreted by two board-certified nuclear medicine physicians who were blinded to any clinical or CT data. The negative predictive value of FDG-PET performed with triple-head coincidence gamma camera (Index test) was compared with a long-term follow-up as a reference standard. Results. Out of 131 patients 73 turned-out to be PET-negative. Of those 73 PET-negative patients, 61 have been scanned after the first-line chemotherapy/radiotherapy, and only 3 of them relapsed in a follow-up (negative predictive value 0.95). Twelve patients with resistant disease have been scanned after the repeated therapy, and 4 of them relapsed in a follow-up period (negative predictive value 0.66). Conclusions. This methodology with a triple-head coincidence gamma camera has a high negative predictive value. A negative PET scan can reassure patients and their doctors that the disease is not active.

Metastatic colorectal cancer to a primary thyroid cancer

BackgroundMetastatic malignancy to the thyroid gland is generally uncommon due to an unfavourable local thyroid micro-environment which impairs the ability of metastatic cells to settle and thrive. Metastases to the thyroid gland have however been reported to occur occasionally particularly if there has been disruption to normal thyroid tissue architecture.Case presentationWe report a patient with a history of surgically resected rectal adenocarcinoma who presents with a rising serum CEA level and an 18F-FDG PET scan positive thyroid nodule which was subsequently confirmed at surgery to be a focus of metastatic rectal adenocarcinoma within a primary poorly differentiated papillary thyroid carcinoma.Subsequent treatment involved right hemi-thyroidectomy, pulmonary wedge resection of oligometastatic metastatic colorectal cancer and chemotherapy.ConclusionMetastatic rectal carcinoma to the thyroid gland and in particular to a primary thyroid malignancy is rare and unusual. Prognosis is likely to be more dependent on underlying metastatic disease rather than the primary thyroid malignancy hence primary treatments should be tailored towards treating and controlling metastatic disease and less emphasis placed on the primary thyroid malignancy.

Clarifying the Diagnosis of Clinically Suspected Recurrence of Cervical Cancer: Impact of 18F-FDG PET

Clarifying the diagnosis of clinically suspected recurrence of cervical cancer can be challenging. The aim of this study was to investigate the clinical value of (18)F-FDG PET in this context. The medical records of a cohort of 40 (18)F-FDG PET referrals in whom recurrence of cervical cancer was clinically suspected were reviewed. Two expert gynecologic oncologists assessed the level of pre-PET clinical doubt, quality of pre-PET work-up, and impact of (18)F-FDG PET on diagnostic understanding and management using questionnaires. In patients with clinically equivocal recurrence, (18)F-FDG PET had a sensitivity of 92% and a specificity of 93% (prevalence, 65%). Before (18)F-FDG PET, there was high disagreement about the adequacy of the conventional work-up (intraclass correlation coefficient [ICC], 0.25) and the presence of recurrence (ICC, 0.24). (18)F-FDG PET increased experts' confidence (median increase, 14% and 25%; P < 0.0001) and diagnostic agreement (from 68% to 98%; ICC, from 0.24 to 0.95). When (18)F-FDG PET was positive for recurrence, the median overall survival was 13 mo. For patients with negative (18)F-FDG PET findings, the median survival was not reached (log rank, 15.50, P = 0.0001). When the treatment plan was categorized as local therapy, systemic therapy, and expectative management, (18)F-FDG PET changed the treatment plan in half of all cases. The 2 experts reported that (18)F-FDG PET led to a better diagnosis and a beneficial change in management in, respectively, 60% and 65% of cases. (18)F-FDG PET can help to clarify the diagnosis of clinically suspected recurrence of cervical cancer. In this patient population, (18)F-FDG PET had significant value in diagnostic understanding and management of recurrent cervical cancer, facilitating decision making and treatment planning. Therefore, (18)F-FDG PET should be part of the diagnostic work-up in detection of recurrent cervical cancer. The high positive predictive value of (18)F-FDG PET in these patients suggests that inclusion in intervention trials might be based on a positive (18)F-FDG PET scan.

Focal Increased Activity in the Liver on 18F-FDG PET Scan Secondary to Brachiocephalic Vein and Superior Vena Cava Obstruction

We present 2 cases demonstrating focal increased activity in the liver on 18F-fluorodeoxyglucose positron emission tomography scans resulting from central venous obstruction and increased blood flow to select regions of the liver via collateral veins. Collateral venous pathways from anterior chest wall veins to the portal veins can form via paraumbilical veins (including the vein of Burrow and the superior and inferior veins of Sappey) or subcapsular veins of the liver via musculophrenic vessels. Imagers should be familiar with the phenomenon of focally increased uptake of 18F-fluorodeoxyglucose in the liver secondary to collateral blood flow to avoid mischaracterizing the liver abnormalities as malignant in etiology.

The Utility of 18-F-Fluorodeoxyglucose Positron Emission Tomography in Evaluation of Bone Marrow Involvement by Non-Hodgkin Lymphoma

In non-Hodgkin lymphomas (NHLs), the bone marrow (BM) involvement is a sign of extensive disease and the iliac crest BM biopsy (BMB) is the established method for the detection of BM infiltration. However, iliac crest BMB is associated with a high rate of false negative results. We assess the ability of 18-F-fluorodeoxyglucose positron emission tomography (F-FDG PET) scan to ascertain the presence of BM involvement in NHL. After reviewing charts of histologically proven NHLs, 97 patients were eligible for our study. All patients were examined by whole-body F-FDG PET scan for initial staging, and all had unilateral posterior iliac crest BMB. BM involvement was established after the result of unilateral posterior iliac crest BMB and image-guided BMB after positive F-FDG PET scan in selected patients. Our data demonstrate an overall sensitivity of 79% for the F-FDG PET scan detecting BM involvement in all patients and specificity of 91%. Further analysis revealed no significant difference in the ability of the F-FDG PET scan to detect BM involvement between the indolent-NHL and the aggressive/highly aggressive-NHL groups (sensitivity P = 0.23, specificity P = 0.64). F-FDG PET scan shows potential to detect BM involvement in NHL. In particular, image-guided repeat BMB should be considered in patients with negative initial iliac crest BMB, whose F-FDG PET scan demonstrates BM involvement in a different site.