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Annals of Nuclear Medicine (v.22, #3)
Low density of sigma1 receptors in early Alzheimer’s disease by Masahiro Mishina; Masashi Ohyama; Kenji Ishii; Shin Kitamura; Yuichi Kimura; Kei-ichi Oda; Kazunori Kawamura; Toru Sasaki; Shiro Kobayashi; Yasuo Katayama; Kiichi Ishiwata (pp. 151-156).
The sigma1 receptor is considered to be involved in cognitive function. A postmortem study reported that the sigma1 receptors were reduced in the hippocampus in Alzheimer’s disease (AD). However, in vivo imaging of sigma1 receptors in the brain of AD patients has not been reported. The aim of this study is to investigate the mapping of sigma1 receptors in AD using [11C]SA4503 positron emission tomography (PET).We studied five AD patients and seven elderly volunteers. A dynamic series of decay-corrected PET data acquisition was performed for 90 min starting at the time of the injection of 500 MBq of [11C]SA4503. A two-tissue three-compartment model was used to estimate K 1, k 2, k 3, k 4, and the delay between metabolite-corrected plasma and tissue time activity using a Gauss-Newton algorithm. The ratio of k 3 to k 4 was computed as the binding potential (BP), which is linearly related to the density of sigma1 receptors. Unpaired t tests were used to compare K 1 and BP in patients with AD and normal subjects.As compared with normals, BP in the AD was significantly lower in the frontal, temporal, and occipital lobe, cerebellum and thalamus, whereas K 1 was significantly lower in the parietal lobe.[11C]SA4503 PET can demonstrate that the density of cerebral and cerebellar sigma1 receptors is reduced in early AD.
Keywords: Alzheimer’s disease; Positron emission tomography; Sigma1 receptor; Cortex; Cerebellum
Preliminary retrospective investigation of FDG-PET/CT timing in follow-up of ablated lung tumor by Fumiyo Higaki; Yoshihiro Okumura; Shuhei Sato; Takao Hiraki; Hideo Gobara; Hidefumi Mimura; Shiro Akaki; Toshihide Tsuda; Susumu Kanazawa (pp. 157-163).
The aim of this study was to clarify the most appropriate follow-up initiation time point for positron emission tomography (PET)/computed tomography (CT) following radio frequency ablation (RFA) of lung tumors, and the cutoff values of maximum standard uptake value (SUVmax) to evaluate local tumor progression.We enrolled 15 patients (8 men, median age 62 years) with 60 tumors, who were treated with RFA of lung tumors and underwent fluorodeoxyglucose (FDG)-PET/CT following RFA. Local tumor progression was assessed by periodic chest CT images prior to and following intravenous administration of a contrast medium. The SUVmax of three periods, namely, 0–3 months, 3–6 months, and 6–9 months after RFA, was evaluated. The appropriate time point for follow-up initiation and the cutoff value of SUVmax were determined using receiver-operating characteristic (ROC) analysis.The median follow-up period was 357 days. Of 60 tumors, 10 showed local progression. The area under the ROC curve (Az) for the 6–9 months (P = 0.044) was the largest and almost equal to that of the 3–6 months (P = 0.024). Az for the 0–3 months was the smallest and statistically insignificant (P = 0.705). The cutoff value of 1.5 of SUVmax at 3–9 months after RFA showed 77.8% sensitivity and 85.7–90.5% specificity.The appropriate follow-up initiation time point is at least 3 months following RFA. Thus, SUVmax is a useful and reliable predictive indicator.
Keywords: Radio frequency ablation; PET/CT; Local tumor progression; Lung tumor; SUV
Fluoro-deoxy-glucose positron emission tomography for evaluation of indeterminate lung nodules: assigning a probability of malignancy may be preferable to binary readings by Suk C. Kim; Josef Machac; Borys R. Krynyckyi; Karin Knesaurek; Daniel Krellenstein; Barbara Schultz; Allen Gribetz; Louis DePalo; Alvin Teirstein; Chun K. Kim (pp. 165-170).
To assess the diagnostic value of fluorine-18 fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) using standard uptake values (SUV) in the differential diagnoses of indeterminate pulmonary nodules. Specifically, we assessed the probability of malignancy for various SUV ranges, and compared the diagnostic efficacy of SUV with and without correction for partial volume effects on the basis of lesion size.The FDG-PET scans performed on 158 patients with biopsy-proven pulmonary lesions seen on computed tomography (CT) scan were retrospectively reviewed. Histopathological confirmation was obtained to establish the diagnosis of the lesions. A region of interest (ROI) was drawn for each lesion, and FDG uptake was quantified (SUVraw). The SUVraw values were normalized for the “size” of the pulmonary lesions measured on CT (SUVsize). Sensitivity and specificity of FDG-PET for pulmonary lesions <2 cm in diameter or ≥2 cm in diameter were determined at SUV cutoff values of 2.5. The areas under the receiver-operating characteristic (ROC) curve for SUVraw and SUVsize regarding the presence of malignancy were compared for statistical differences. The frequency of malignant lesions for each range of SUVs was obtained to produce the probability of cancer (POC).The mean SUVraw was 3.17 ± 2.76 and 9.18 ± 6.72 for benign and malignant lesions, respectively. When a SUVraw value of 2.5 was used as a cutoff, sensitivity and specificity were 89% and 51%, respectively, for all lesion sizes. The sensitivity and specificity at a cutoff SUVraw of 2.5 for lesions less than 2 cm in diameter were 75% and 72%, respectively, and 92% and 41% for lesions 2 cm or greater, respectively. The sensitivity and specificity at a cutoff SUVsize of 2.5 were 88% and 42%, respectively. The area under the ROC curves for SUVraw and SUVsize was 0.816 and 0.743, respectively (P value 0.034). When the SUVraw was divided into three groups, the probability of malignancy was 26% when the SUVraw was <2, 57% for 2 ≤ SUVraw < 6, and 89% for SUVraw ≥ 6.The FDG-PET is a reasonably accurate and useful tool for characterizing the nature of indeterminate pulmonary lesions, although the specificity was not as high as that reported in the literature, probably owing in part to our patient population and selection bias. Our data suggest that reporting the results of PET studies as a probability rather than as positive or negative for malignancy would be more useful for further management decision making. Correction of SUVs for tumor size did not improve accuracy.
Keywords: Pulmonary nodule; FDG; PET; Size; Probability of cancer
Fluoro-deoxy-glucose positron emission tomography for evaluation of indeterminate lung nodules: assigning a probability of malignancy may be preferable to binary readings by Suk C. Kim; Josef Machac; Borys R. Krynyckyi; Karin Knesaurek; Daniel Krellenstein; Barbara Schultz; Allen Gribetz; Louis DePalo; Alvin Teirstein; Chun K. Kim (pp. 165-170).
To assess the diagnostic value of fluorine-18 fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) using standard uptake values (SUV) in the differential diagnoses of indeterminate pulmonary nodules. Specifically, we assessed the probability of malignancy for various SUV ranges, and compared the diagnostic efficacy of SUV with and without correction for partial volume effects on the basis of lesion size.The FDG-PET scans performed on 158 patients with biopsy-proven pulmonary lesions seen on computed tomography (CT) scan were retrospectively reviewed. Histopathological confirmation was obtained to establish the diagnosis of the lesions. A region of interest (ROI) was drawn for each lesion, and FDG uptake was quantified (SUVraw). The SUVraw values were normalized for the “size” of the pulmonary lesions measured on CT (SUVsize). Sensitivity and specificity of FDG-PET for pulmonary lesions <2 cm in diameter or ≥2 cm in diameter were determined at SUV cutoff values of 2.5. The areas under the receiver-operating characteristic (ROC) curve for SUVraw and SUVsize regarding the presence of malignancy were compared for statistical differences. The frequency of malignant lesions for each range of SUVs was obtained to produce the probability of cancer (POC).The mean SUVraw was 3.17 ± 2.76 and 9.18 ± 6.72 for benign and malignant lesions, respectively. When a SUVraw value of 2.5 was used as a cutoff, sensitivity and specificity were 89% and 51%, respectively, for all lesion sizes. The sensitivity and specificity at a cutoff SUVraw of 2.5 for lesions less than 2 cm in diameter were 75% and 72%, respectively, and 92% and 41% for lesions 2 cm or greater, respectively. The sensitivity and specificity at a cutoff SUVsize of 2.5 were 88% and 42%, respectively. The area under the ROC curves for SUVraw and SUVsize was 0.816 and 0.743, respectively (P value 0.034). When the SUVraw was divided into three groups, the probability of malignancy was 26% when the SUVraw was <2, 57% for 2 ≤ SUVraw < 6, and 89% for SUVraw ≥ 6.The FDG-PET is a reasonably accurate and useful tool for characterizing the nature of indeterminate pulmonary lesions, although the specificity was not as high as that reported in the literature, probably owing in part to our patient population and selection bias. Our data suggest that reporting the results of PET studies as a probability rather than as positive or negative for malignancy would be more useful for further management decision making. Correction of SUVs for tumor size did not improve accuracy.
Keywords: Pulmonary nodule; FDG; PET; Size; Probability of cancer
Attenuation corrected gated SPECT for the assessment of left ventricular ejection fraction and volumes by Riemer H. J. A. Slart; René A. Tio; Clark J. Zeebregts; Antoon T. M. Willemsen; Rudi A. J. O. Dierckx; Johan De Sutter (pp. 171-176).
The aim of this study was to evaluate the value of attenuation correction (AC) of Tc-99m tetrofosmin single-photon emission tomography (SPECT) imaging for the assessment of left ventricular ejection fraction (LVEF).Attenuation corrected and non-attenuation corrected (NC) resting Tc-99m tetrofosmin SPECT were compared for the assessment of LVEF. Planar multigated radionuclide angiography (MUGA) served as the reference for LVEF assessment. Patients (n = 56) with left ventricular dysfunction who underwent MUGA and rest gated Tc-99m tetrofosmin SPECT within 1 month were included.The average LVEF on NC gated SPECT was 37.4 ± 11.8% and on AC SPECT 38.5 ± 13.4% (P = NS). The absolute mean difference of the LVEF between the MUGA and NC gated SPECT and AC gated SPECT was −0.2% (95% CI −1.7 to 1.3) and −1.3% (95% CI −2.7 to 0.03), respectively (P = NS both vs. MUGA). The correlation between NC gated SPECT and AC gated SPECT versus MUGA measurement was high with a correlation coefficient of 0.89 (P < 0.01) and 0.92 (P < 0.01), respectively. End-diastolic volumes (EDVs) and end-systolic volumes (ESVs) were significantly higher with AC gated SPECT when compared with NC gated SPECT (both P < 0.001).Profile AC gated Tc-99m tetrofosmin SPECT agrees well with MUGA and NC gated Tc-99m tetrofosmin SPECT for the assessment of LVEF. EDVs and ESVs are significantly higher with AC gated SPECT when compared with NC gated SPECT.
Keywords: Attenuation correction; Gated Tc-99m tetrofosmin SPECT; MUGA; LVEF
Assessment of cervical lymph node metastases using FDG-PET in patients with head and neck cancer by Yutaka Yamazaki; Masaaki Saitoh; Ken-ichi Notani; Kanchu Tei; Yasunori Totsuka; Shu-ichi Takinami; Kakuko Kanegae; Masayuki Inubushi; Nagara Tamaki; Yoshimasa Kitagawa (pp. 177-184).
To evaluate the diagnostic accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) relative to computed tomography (CT) for detecting metastatic cervical lymph nodes in patients with squamous cell carcinoma of the head and neck (HNSCC), and to ascertain the factors that affect this accuracy.A total of 1076 lymph nodes obtained from 35 neck dissections in 26 HNSCC patients who preoperatively underwent both FDG-PET and CT were retrospectively analyzed. For pathological metastatic lymph nodes, the lymph node size (short-axis diameter), the ratio of intranodal tumor deposits, and the size of intranodal tumor deposits (maximum diameter of metastatic foci in each lymph node) were histologically recorded.Forty-six lymph nodes from 23 neck sides were pathologically diagnosed metastases. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET evaluated individually per neck side were 74%, 92%, 80%, 94%, and 65%, respectively, whereas those of CT were 78%, 58%, 71%, 78%, and 58%, respectively. FDG-PET detected 100% of metastatic lymph nodes ≥10 mm, intranodal tumor deposits ≥9 mm, and intranodal tumor deposits with a ratio >75%, whereas no nodes or tumor deposits smaller than 5 mm were detected. The spatial resolution limitations of FDG-PET were responsible for 16 of 20 (80%) false-negative PET results in lymph nodes.FDG-PET is a useful tool for preoperative evaluation of the neck because it accurately detects metastatic lymph nodes ≥10 mm and has fewer false-positive cases than CT. The high specificity of FDG-PET for lymph node metastases may play an important role in avoiding unnecessary neck dissection.
Keywords: FDG-PET; Metastasis; Lymph node dissection; Head and neck cancer
Differential effects comparing exercise and pharmacologic stress on left ventricular function using gated Tc-99m sestamibi SPECT by Yuka Ohtaki; Taishiro Chikamori; Yuko Igarashi; Satoshi Hida; Hirokazu Tanaka; Tsuguhisa Hatano; Yasuhiro Usui; Manabu Miyagi; Akira Yamashina (pp. 185-190).
Although post-ischemic stunning has emerged as an important marker for severe coronary artery disease (CAD), differences in stress methods may have different effects on left ventricular (LV) volumes and function.To assess differential effects comparing exercise and pharmacologic stress on the LV measurements, 99mTc-sestamibi gated single-photon emission computed tomography (SPECT) acquired more than 30 min after stress and at rest was evaluated in 38 patients undergoing adenosine triphosphate (ATP) stress (ATP group) and 38 age-and sex-matched patients subjected to exercise stress (Ex group) among 268 patients with normal SPECT findings.Coronary risk factors and LV volumetric measurements at baseline were similar in the two groups. Compared with volumetric measurements at rest, enddiastolic volume (EDV) increased (72 ± 21 ml to 74 ± 21 ml; P = 0.01), end-systolic volume increased (25 ± 12 ml to 28 ± 13 ml; P = 0.001), and ejection fraction (EF) decreased after stress (66% ± 8% to 63% ± 9%; P < 0.002) in the ATP group. In the Ex group, by contrast, no such change was observed. In addition, changes in EDV (3 ± 6 vs. −1 ± 5 ml; P = 0.01) and the stress-to-rest ratio of EDV (1.04 ± 0.09 vs. 0.99 ± 0.08; P < 0.02) after stress were greater in the ATP than in the Ex group.Differential effects of stress methods on LV volumes persist more than 30 min after the stress. These findings should be kept in mind when interpreting post-ischemic stunning.
Keywords: Quantitative gated single-photon emission computed tomography; Normalcy; Myocardial stunning; Transient ischemic dilation
Influence of mild hyperglycemia on cerebral FDG distribution patterns calculated by statistical parametric mapping by Keiichi Kawasaki; Kenji Ishii; Yoko Saito; Keiichi Oda; Yuichi Kimura; Kiichi Ishiwata (pp. 191-200).
In clinical cerebral 2-[18F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) studies, we sometimes encounter hyperglycemic patients with diabetes mellitus or patients who have not adhered to the fasting requirement. The objective of this study was to investigate the influence of mild hyperglycemia (plasma glucose range 110–160 mg/dl) on the cerebral FDG distribution patterns calculated by statistical parametric mapping (SPM).We studied 19 healthy subjects (mean age 66.2 years). First, all the subjects underwent FDG-PET scans in the fasting condition. Then, 9 of the 19 subjects (mean age 64.3 years) underwent the second FDG-PET scans in the mild hyperglycemic condition. The alterations in the FDG-PET scans were investigated using SPM-and region of interest (ROI)-based analyses. We used three reference regions: (1) SPM global brain (SPMgb) used for SPM global mean calculation, (2) the gray and white matter region computed from magnetic resonance image (MRIgw), and (3) the cerebellar cortex (Cbll).The FDG uptake calculated as the standardized uptake value (average) in SPMgb, MRIgw, and Cbll regions in the mild hyperglycemic condition was 42.7%, 41.3%, and 40.0%, respectively, of that observed in the fasting condition. In SPM analysis, the mild hyperglycemia was found to affect the cerebral distribution patterns of FDG. The FDG uptake was relatively decreased in the gray matter, mainly in the frontal, temporal, and parietal association cortices, posterior cingulate, and precuneus in both SPMgb-and MRIgw-reference-based analyses. When Cbll was adopted as the reference region, those decrease patterns disappeared. The FDG uptake was relatively increased in the white matter, mainly in the centrum semiovale in all the reference-based analyses.It is noteworthy that the FDG distribution patterns were altered under mild hyperglycemia in SPM analysis. The decreased uptake patterns in SPMgb-(SPM default) and MRIgw-reference-based analyses resembled those observed in Alzheimer’s disease. Under mild hyperglycemia, we can recommend Cbll as the reference region to detect decreased uptake patterns. We should pay special attention to controlling the diet condition, monitoring hyperglycemia, and optimizing the reference region in SPM analysis, particularly in the diagnosis of early Alzheimer’s disease in clinical FDG-PET.
Keywords: FDG-PET; Mild hyperglycemia; Distribution pattern; Statistical parametric mapping; Alzheimer’s disease
Statistical parametric mapping analysis of the relationship between regional cerebral blood flow and symptom clusters of the depressive mood in patients with pre-dialytic chronic kidney disease by Seong-Jang Kim; Sang Heon Song; Ji Hoon Kim; Ihm Soo Kwak (pp. 201-206).
The aim of this study is to investigate the relationship between regional cerebral blood flow (rCBF) and symptom clusters of depressive mood in pre-dialytic chronic kidney disease (CKD).Twenty-seven patients with stage 4–5 CKD were subjected to statistical parametric mapping analysis of brain single-photon emission computed tomography. Correlation analyses between separate symptom clusters of depressive mood and rCBF were done.The first factor (depressive mood) was negatively correlated with rCBF in the right insula, posterior cingulate gyrus, and left superior temporal gyrus, and positively correlated with rCBF in the left fusiform gyrus. The second factor (insomnia) was negatively correlated with rCBF in the right middle frontal gyrus, bilateral cingulate gyri, right insula, right putamen, and right inferior parietal lobule, and positively correlated with rCBF in left fusiform gyrus and bilateral cerebellar tonsils. The third factor (anxiety and psychomotor aspects) was negatively correlated with rCBF in the left inferior frontal gyrus, right superior frontal gyrus, right middle temporal gyrus, right superior temporal gyrus, and left superior frontal gyrus, and positively correlated with rCBF in the right ligual gyrus and right parahippocampal gyrus.In this study, the separate symptom clusters were correlated with specific rCBF patterns similar to those in major depressive disorder patients without CKD. However, some areas with discordant rCBF patterns were also noted when compared with major depressive disorder patients. Further larger scale investigations are needed.
Keywords: Chronic kidney disease; Depression; Statistical parametric mapping; Tc-99m ECD SPECT
Accumulation of gallium-67 within mature and immature teratoma in pediatric patients: investigation for the uptake mechanism by Etsuo Kunieda; Hiroko Hara; Yukihiko Morikawa; Seiichi Hirobe; Shoichiro Kamagata; Atsushi Kubo (pp. 207-213).
We encountered cases of mature and immature teratoma with positive uptake of 67Ga. The objective of this study is to investigate the mechanism of 67Ga accumulation within mature and immature teratomas by comparing the findings of gallium scan, computed tomography (CT), and autoradiography of surgical specimens with the pathological findings.The subjects comprised 14 children who underwent surgical resection for intra-abdominal mature and immature teratomas, which were histologically proved to be of the mature and immature subtype. Their age ranged from 24 days to 14 years. The origins of the mature teratomas consisted of seven ovaries including one bilateral case, two retroperitoneal, and two sacrococcygeal regions. The origins of the immature teratomas were retroperitoneum in two cases, an ovary and a sacrococcygeal region. Complete surgical excision was feasible in all children. They underwent both gallium scan and CT prior to surgery. Single-photon emission computed tomography was added in some cases. For two gallium-positive cases, radiography and scintigraphy (autoradiography) of the resected specimen were performed.Of the 14 children, 5 (one with immature and four with mature subtype) showed positive 67Ga uptake within tumors, which originated from the retroperitoneum in the 3 boys, and from the ovary in the 2 girls. All had typical CT findings of teratoma, including calcifications, fat components, cystic areas, and solid parts. 67Ga accumulation in the four mature teratomas appeared discretely strong, and was considered to correspond with intralesional calcifications. However, in the remaining one immature teratoma, the gallium distribution was diffuse within the tumor. The comparison between radiography and autoradiography of the resected mature teratomas confirmed the correlation between the intralesional calcifications and areas of 67Ga accumulation.A high-uptake ratio of 67Ga in benign teratoma was indicated. A close correlation between gallium scan and CT helps to ascertain whether 67Ga uptake results from malignant and/or immature elements, or mature tissue components.
Keywords: Teratoma; Benign tumor; Calcification; 67Ga
Extrapancreatic F-18 FDG accumulation in autoimmune pancreatitis by Motohiro Sato; Toshiyuki Okumura; Yasukazu Shioyama; Jyouji Imura (pp. 215-219).
We report two cases of autoimmune pancreatitis (AIP) in which fluorine-18 fluorodeoxyglucose (FDG) showed moderate accumulation in the pancreas, as well as in bilateral submandibular glands and in multifocal lymph nodes. FDG positron emission tomography (PET)/computed tomography (CT) is a useful diagnostic tool to assess the extrapancreatic lesions of AIP, which is a recently proposed new clinicopathological entity named immunoglobulin G4 (IgG4)-related systemic disease. Recognition of the FDG-PET/CT findings of IgG4-related sclerosing disease is crucial to avoid unnecessary surgery or other intervention because of similarities to malignant lymphoma or malignant tumor with multiple lymph node metastases.
Keywords: Autoimmune pancreatitis (AIP); Sclerosing sialoadenitis; IgG4-related sclerosing disease; Positron emission tomography (PET); Fluorine-18 fluorodeoxyglucose (F-18 FDG)
Clinical usefulness of thallium-201 scintigraphy and magnetic resonance imaging in the diagnosis of chondromyxoid fibroma by Hiroaki Murata; Naoyuki Horie; Takaaki Matsui; Takanori Akai; Hideki Ueda; Yasushi Oshima; Eiichi Konishi; Toshikazu Kubo (pp. 221-224).
Chondromyxoid fibroma (CMF) is a benign bone tumor. However, it is sometimes difficult to distinguish this tumor from chondrosarcoma. We report a rare case arising from the proximal fibula, presenting multimodality imaging features. An 18-year-old man presented with a 2-year history of gradually increasing pain and swelling in his left knee. Radiograph showed an area of osteolysis with lobulation. Magnetic resonance (MR) imaging demonstrated that almost the whole lesion was enhanced with Gd-DTPA. Scintigraphy examination with 99mTc-biphosphonate showed strong accumulation in the periphery. On Ga-67-citrate scintigraphy, there was a little uptake. Thallium-201 scintigraphy showed strong accumulation of the whole lesion in early and late scans. The tumor was diagnosed as CMF by open biopsy. It is important that CMF is correctly distinguished from other tumors because this may be histologically overdiagnosed as chondrosarcoma. Contrast-enhanced MR imaging and thallium-201 scintigraphy may be useful to distinguish CMF from benign bone tumors or chondrosarcoma.
Keywords: Chondromyxoid fibroma; Thallium-201 scintigraphy; MRI; Proximal fibula
Primary synovial sarcoma of the kidney: use of PET/CT in diagnosis and follow-up by Sakip Erturhan; İlker Seçkiner; Sabri Zincirkeser; Ahmet Erbaǧci; Mehmet Çelik; Faruk Yaǧci; Metin Karakok (pp. 225-229).
Primary renal synovial sarcoma is a rarely seen renal neoplasm. An experienced uropathologist is needed to make the pathological diagnosis. A patient, operated on with a prediagnosis of renal cell carcinoma, the pathology of which was reported as synovial sarcoma, is presented in this article. 18F-fluoro-deoxyglucose positron emission tomography and computed tomography were performed preoperatively and in the postoperative follow-up to detect the primary tumor and lymph node metastases.
Keywords: Renal tumor; Synoviol sarcoma; PET/CT
Brown adipose tissue demonstrating intense FDG uptake in a patient with mediastinal pheochromocytoma by Ichiei Kuji; Etsuko Imabayashi; Akinobu Minagawa; Hiroshi Matsuda; Tsutomu Miyauchi (pp. 231-235).
We present an interesting case with a central mediastinal pheochromocytoma showing intense F-18 fluorodeoxyglucose (FDG) uptake in tumor and systemic brown adipose tissue (BAT) mimicking metastases. The findings of hypertension and high plasma catecholamine concentration suggested the presence of pheochromocytoma. Mediastinal tumor showed intense FDG uptake and faint uptake of I-131 metaiodobenzylguanidine. Intense FDG uptake was demonstrated in cervical, paravertebral, mediastinal, and perirenal regions. Positron emission tomography and computed tomography (PET/CT) revealed uptake in a fat density area suggesting that the FDG uptake had occurred in BAT. The mediastinal tumor was resected along with an adhesion to the left atrial wall and pathologically confirmed as pheochromocytoma. The plasma catecholamine concentration and blood pressure then reverted to normal. The FDG uptake in BAT disappeared after tumor resection.
Keywords: Brown adipose tissue; Extra-adrenal pheochromocytoma; F-18 fluorodeoxyglucose; Positron emission tomography