Annals of Nuclear Medicine (v.23, #8)

Orthopedic surgical procedures often create some special postoperative complications, which may demonstrate abnormally increased or focal uptake for an extended period of time on FDG PET-CT images. The distinction of normal from pathologic, benign from malignant uptake is very important to minimize the number of false positive results. To date, very little data have been published regarding surgical-related benign musculoskeletal uptake on PET-CT imaging. In this paper, we present to the readers some case examples of FDG PET-CT imaging for postoperative fracture, infection or osteomyelitis, metallic implants, aggressive bone edge, heterotopic ossification, granuloma and neuroma. We also discuss potential pitfalls to recognize these orthopedic surgery-related complications and identify benign nature of increased FDG uptake. In all cases, the patient’s medical and surgical history would be of paramount importance to the radiologists/nuclear medicine physicians who interprets the scan. It is also crucial to carefully correlate FDG uptake with the anatomy on the co-registered CT images in all transaxial, coronal and sagittal views in order to identify the location and pattern of uptake.
Keywords: FDG PET-CT; Osteomyelitis; Bone edge; Heterotopic ossification; Granuloma; Neuroma

Clinical impact of whole body FDG-PET for recurrent biliary cancer: a multicenter study by Kazuhiro Kitajima; Koji Murakami; Kakuko Kanegae; Nagara Tamaki; Tomohiro Kaneta; Hiroshi Fukuda; Kotaro Nakajima; Hirofumi Fujii; Ukihide Tateishi; Kazuo Kubota; Tsuyoshi Suga; Yuji Nakamoto (709-715).
To evaluate the clinical usefulness of positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) in patients with follow-up or suspected recurrent biliary cancer in a multicenter study.We performed a retrospective review of 50 patients who underwent FDG-PET (either integrated PET/CT or manual fusion of dedicated PET and CT) scans for post-treatment surveillance of biliary cancer. Recurrence was suspected in 40 of these patients on the basis of tumor marker levels, and/or findings of conventional imaging (group A). Clinical findings in the remaining 10 patients showed them to be disease-free (group B). The diagnostic performance and clinical impact of PET were analyzed.Recurrence was confirmed in 28 out of the 40 patients in group A, and 1 of the 10 patients in group B. Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET for detecting recurrence were 86% (25/29), 91% (19/21), and 88% (44/50), respectively. The one patient with recurrence in group B was correctly interpreted by PET. Positive test likelihood ratio and negative test likelihood ratio were increased from 1.69 to 9.05, and 0.08 to 0.32, respectively, after PET study. The findings of PET resulted in a change of management for 10 out of the 50 patients (20%) by initiating an unplanned treatment strategy (n = 7), by obviating the need for planned diagnostic procedures (n = 2), or by changing the treatment plan (n = 1).FDG-PET/CT or PET with CT yielded helpful information in patients with suspected recurrent biliary cancer.
Keywords: Biliary cancer; Recurrence; 18F-FDG; PET; PET/CT

Vasodilatory effect of adenosine triphosphate does not change cerebral blood flow: a PET study with 15O-water by Raihan Hussain; Tatsuro Tsuchida; Takashi Kudo; Masato Kobayashi; Tetsuya Tsujikawa; Yasushi Kiyono; Yasuhisa Fujibayashi; Hidehiko Okazawa (717-723).
Adenosine triphosphate (ATP) is the parent compound of adenosine and well known as a powerful vasodilator. To investigate the effect of ATP on cerebral blood flow (CBF) and cerebral vessels, 15O-water positron emission tomography (PET) studies were performed to evaluate changes in CBF and blood volume before and after ATP administration.Ten healthy young volunteers underwent 15O-water PET scans under the conditions of baseline, 3 and 1 min after ATP continuous infusion. CBF values in cortical regions of the bilateral middle cerebral arteries and basal ganglia were obtained for each subject. Statistical parametric mapping (SPM) was applied for analysis of regional changes. Physiologic parameters, such as blood gas and blood pressure were also measured.Cortical CBF showed no significant change after continuous infusion of ATP compared with the baseline. Dilatation of major vessels induced by ATP was visualized on SPM analysis. Heart rates increased and mean blood pressure decreased during ATP administration while blood gas data showed no changes between the different conditions.Intravenous ATP administration caused dilatation of major cerebral vessels but no significant change in CBF under normoventilation and decrease in systemic blood pressure, indicating that this no change in CBF under vasodilatory effect of ATP may be caused by cerebral microvascular autoregulation.
Keywords: ATP; Cerebral blood flow; Vasodilation; Cerebral autoregulation; Statistical parametric mapping

Significance of abnormal myocardial perfusion scintigraphy in young adult patients with SLE by Seyed Rasoul Zakavi; Mohammad Hasan Jokar; Vahid Reza Dabbagh Kakhki; Ghodsieh Khazaei; Ramin Sadeghi (725-728).
Detection of subclinical coronary artery disease (CAD) is a potential challenge in patients with systemic lupus erythematosus (SLE) and it is suggested that myocardial perfusion single photon emission computerized tomography (SPECT) is more sensitive than exercise test in this setting. However, the significance of perfusion abnormalities in SLE patients is not well known. In this study, we evaluated the prognostic significance of myocardial perfusion defects in patients with SLE.Patients with proven diagnosis of SLE admitted to the hospital due to noncardiac problems with no history of CAD were studied. All patients underwent 99mTc-MIBI myocardial perfusion scan using dipyridamole as pharmacological stress. All patients were followed up by reviewing patients file in lupus clinic and any minor or major cardiac events were recorded.Eighteen female and two male patients with mean age of 28.2 ± 12.05 years were included. Six patients had mild reversible perfusion defects with mean summed difference score of 2.5 ± 1.0. Pattern of reverse redistribution (reverse fill-in) was noted in three patients. Eleven patients had normal myocardial perfusion. Hypokinesia was noted in three patients on gated images. One patient with abnormal perfusion died 21 days after imaging due to non-cardiac cause. Nineteen patients were followed for a mean time of 39.2 ± 16.0 months. No major or minor cardiac events were noted during follow-up. Three patients (one with abnormal perfusion) had at least one readmission during follow-up period.Our study showed that myocardial perfusion abnormalities are fairly frequent in SLE patients but the defects are generally mild and do not advocate an adverse prognosis.
Keywords: Myocardial perfusion scan; Systemic lupus erythematosus; 99mTc-sestamibi; Dipyridamole

Incidental thyroid uptake on F-18 FDG PET/CT: correlation with ultrasonography and pathology by Bong Joo Kang; Joo Hyun O; Jun Hyun Baik; So Lyung Jung; Young Ha Park; Soo Kyo Chung (729-737).
To evaluate the usefulness of maximum standard uptake value (max SUV) calculated from F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) examination and findings from ultrasonographic (US) examination on incidentally detected thyroid FDG uptake on FDG PET/CT.We collected and reviewed FDG PET/CT images performed at our institution from March 2005 to March 2008. This study included 190 subjects with increased FDG uptake of thyroid gland who later underwent thyroid US and histological examinations. Of these subjects, the uptake pattern on FDG PET/CT was classified as either diffuse or focal. The FDG uptake pattern, max SUV, and US findings were evaluated and correlated with the histological results.In the focal FDG uptake pattern cases (n = 148), the mean max SUV of malignant cases was higher than that of benign cases (5.93 ± 5.35 vs. 3.47 ± 2.89). Of the diffuse FDG uptake cases (n = 42), nodules were detected in 25 subjects (59.5%) by US examination. Thyroid nodules were well characterized on US studies, and combined findings of suspicious US features or high max SUV of focal FDG uptake lesion increased sensitivity, PPV, NPV, and accuracy.Focal uptake pattern and high max SUV may be helpful in differentiating benign and malignant nodules on FDG PET/CT. However, US examination provides further information, and for lesions with increased FDG uptake of thyroid, US examination should be recommended.
Keywords: FDG; PET/CT; Ultrasonography; Thyroid nodule; Incidentaloma

PET/CT image fusion error due to urinary bladder filling changes: consequence and correction by Sherif I. Heiba; Barbara Raphael; Ivan Castellon; Erkan Altinyay; Nick Sandella; Gerald Rosen; Hussein M. Abdel-Dayem (739-744).
A considerable change of urinary bladder (UB) shape in PET compared with CT in integrated PET/CT system is frequently noted. This study initially evaluated this finding with and without oral contrast (OC) use. In addition, a one bed pelvic section (PLV) repeat acquisition was investigated as a solution to this problem. 18FDG PET/CTs of 88 patients were analyzed. OC was administered in 68 patients, of whom 31 had PLV images taken 5–10 min later. Three-dimensional mid-UB CT and PET matching measurements were compared. In addition, UB walls displacement between CT and PET were analyzed.The mean UB height was significantly increased (P < 0.001) in PET when compared with CT, both anteriorly and posteriorly; however, UB width and depth were not significantly different. An upward shift of superior UB wall in PET from equivalent CT images was noted, whereas there was no appreciable displacement of the other UB walls. The percent UB height increase on PET from CT was significantly greater with than without OC use. The UB height difference between PET and CT was markedly reduced on PLV when compared with the original scans.Caution should be exerted during the interpretation of PET/CT scans of the pelvis as there is significant upward expansion of UB on PET compared with CT that appears to be exaggerated by OC use, likely due to additional fluid load. The PET/CT fusion errors of UB can be substantially resolved through a separate PLV acquisition presumably due to the shorter time interval of UB scan completion between CT and PET.
Keywords: PET/CT; 18FDG; Image fusion; Urinary bladder

To evaluate the role of combination of 18F-FDG PET-CT scan and 68Ga DOTA-TOC PET-CT scan in differentiating bronchial tumors observed in contrast enhanced computed tomography scan of chest.Study design: Prospective observational study.Place of study: All India Institute of Medical Sciences, New Delhi, India.7 patients with bronchial mass detected in computed tomography scan of the chest were included in this study. All patients underwent 18F-FDG PET-CT scan, 68Ga DOTA-TOC PET-CT scan and fiberoptic bronchoscope guided biopsy followed by definitive surgical excision. The results of functional imaging studies were analyzed and the results are correlated with the final histopathology of the tumor.Histopathological examination of 7 bronchial masses revealed carcinoid tumors (2 typical, 1 atypical), inflammatory myofibroblastic tumor (1), mucoepidermoid carcinoma (1), hamartoma (1), and synovial cell sarcoma (1). The typical carcinoids had mild 18F-FDG uptake and high 68Ga DOTA-TOC uptake. Atypical carcinoid had moderate uptake of 18F-FDG and high 68Ga DOTA-TOC uptake. Inflammatory myofibroblastic tumor showed high uptake of 18F-FDG and no uptake of 68Ga DOTA-TOC. Mucoepidermoid carcinoma showed mild 18F-FDG uptake and no 68Ga DOTA-TOC uptake. Hamartoma showed no uptake on either scans. Synovial cell sarcoma showed moderate 18F-FDG uptake and mild focal 68Ga DOTA-TOC uptake.This initial experience with the combined use of 18F-FDG and 68Ga DOTA-TOC PET-CT scan reveals different uptake patterns in various bronchial tumors. Bronchoscopic biopsy will continue to be the gold standard; however, the interesting observations made in this study merits further evaluation of the utility of the combination of 18F-FDG PET-CT scan and 68Ga DOTA-TOC PET-CT scan in larger number of patients with bronchial masses.
Keywords: Bronchial mass; 18F-FDG PET-CT; 68Ga DOTA-TOC PET-CT

Fused FDG-PET and MRI imaging of Takayasu arteritis in vertebral arteries by Anna L. Bartels; Clark J. Zeebregts; Marc Bijl; René A. Tio; Riemer H. J. A. Slart (753-756).
Takayasu arteritis (TA) is an inflammatory vascular disease that mainly affects the aorta and its main branches. Cerebrovascular symptoms are not common and mainly involve the carotid arteries, while the involvement of vertebral arteries is rare. We present a 24-year-old woman with TA that affected both vertebral arteries. Disease activity was detected by 18fluorodeoxyglucose positron-emission tomography (FDG-PET) in the absence of structural abnormalities on magnetic resonance imaging (MRI) and MRA. Although neurological clinical symptomatology suggested the involvement of the vertebral arteries, clear imaging of the anatomical substrate appeared only possible after the fusion of FDG-PET with MRI scans. The fusion of PET and MRI images may be helpful in establishing the diagnosis of active Takayasu arteritis in rare localizations such as the vertebral arteries.
Keywords: Takayasu arteritis; FDG; PET; MRI; Vertebral artery

Usefulness of F-18 FDG PET/CT in the assessment of disseminated Mycobacterium avium complex infection by Motohiro Sato; Takashi Hiyama; Keiko Kaito; Yasutaka Hayashi; Toshiyuki Okumura (757-762).
A patient showing abnormal fluorine-18-fluorodeoxyglucose (FDG) uptake due to disseminated Mycobacterium avium complex (MAC) infection is presented. Increased focal FDG uptake was demonstrated in the cervical and supraclavicular lymph nodes, spleen, and diffuse bone marrow. FDG PET/CT is considered as a useful diagnostic tool to assess the exact extent and activity of disseminated MAC infection. Moreover, it is advantageous over CT and magnetic resonance imaging to assess the treatment response and time course of the disease.
Keywords: Disseminated Mycobacterium avium complex infection; F-18 fluorodeoxyglucose (F-18 FDG); Positron-emission tomography/computed tomography (PET/CT)

Development of an ultra-high resolution SPECT system with a CdTe semiconductor detector by Koichi Ogawa; Naoka Ohmura; Hirokazu Iida; Kayoko Nakamura; Tadaki Nakahara; Atsushi Kubo (763-770).
The aim of this work was to evaluate an ultra-high spatial resolution SPECT system with a semiconductor detector and a high-resolution parallel-hole collimator or a pinhole collimator for small animal imaging.We evaluated an ultra-high spatial resolution SPECT system with a high-resolution parallel-hole collimator attached to a cadmium telluride (CdTe) semiconductor detector for small animal imaging. The sizes of an active area and a pixel in the semiconductor detector were 44 × 44 and 0.5 × 0.5 mm2, respectively. In the high-resolution parallel-hole collimator the size of a hole was 0.4 × 0.4 mm2, the thickness of a septum 0.1 mm, and the hole-length 30 mm. We also used a high-resolution pinhole collimator with a hole size of 0.3 or 0.5 mmϕ. The physical performance of this SPECT system was evaluated with some experiments with phantoms filled with 99mTc-pertechnatate solution. In addition ideal performance and limitations of the system were evaluated with Monte Carlo simulations under the same geometrical conditions as in the experiments. In the evaluation for small animal imaging, we used mice that were administered with 99mTc-MDP. We also conducted an ultra-high resolution X-ray CT of the mice to verify the accumulated location of 99mTc-MDP using the bone CT images of the mice.The results of the phantom experiments showed that we could resolve 1 mmϕ hot-channels and 1.6 mmϕ cold-rods with the high-resolution parallel-hole collimator and pinhole collimators. We could image 0.3 mmϕ hot-channels with the high-resolution pinhole collimators. The results of the simulations showed that the resolution limit in the pinhole imaging was about 0.6 mm FWHM. And the results of experiments with mice showed that we could reconstruct high-resolution images of 99mTc-MDP. Furthermore, the distribution of 99mTc-MDP in a mouse was found to correspond closely to the location of the bones of the mouse in reconstructions made with the ultra-high resolution X-ray CT system.Our results demonstrated that the ultra-high spatial resolution SPECT system was feasible for small animal imaging allowing a relatively long data acquisition time.
Keywords: Semiconductor detector; Spatial resolution; SPECT; Small animal imaging