Alfred C. Liao

Cervical lymphadenopathy caused by Kikuchi disease: positron emission tomographic appearance.

A 26-year-old woman whose chief symptom was palpable but painless cervical lymphadenopathy and fever underwent a whole-body fluorodeoxyglucose (FDG) positron emission tomographic (PET) study. FDG uptake was increased in the right neck, bilateral supraclavicular fossae, mediastinum, left pulmonary hilum, and left axillary nodes. The histopathologic diagnosis was histiocytic necrotizing lymphadenitis (Kikuchi disease). The patient received no treatment and the lymphadenopathy disappeared spontaneously after 3 months.

Application of 18F-FDG PET/CT in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy occurring worldwide, with particularly high frequencies in Southern China, Hong Kong, Singapore and Taiwan. Imaging is vital for detection, staging, and treatment. 2-[Fluorine-18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) has been shown to be a valuable imaging tool in patients for initial staging and restaging diagnosis of NPC. Dual-modality positron emission tomography/computed tomography (PET/CT) provides the technical basis for intrinsically aligned functional and morphologic data sets. The false-negative and false-positive rate may be decreased by using combined FDG-PET/CT. FDG-PET/CT may be as a standard clinical imaging modality in the staging of NPC and in the detection of recurrent disease after radiotherapy. It could provide valuable information in localizing primary tumor in patients with neck nodal metastases from an unknown primary tumor.

Incidental Pituitary Macroadenoma Detected In FDG-PET: Three Cases Report

Intense 18F-fluorodeoxyglucose(FDG)uptake in the suprasellar region is suggestive of pituitary adenoma by its relative high prevalence. Three cases of pituitary macroadenoma were identified in consecutive 1,166studies of FDG-PET from non-selective 1,140 examinees(subtract repeat scans, and exclude scans for heart only).The prevalence in this mixed-age population is 0.26%.Subsequent workup revealed nonfunctioning macroadenoma ranging in size from 1.5cm to3.3cm,and at least one case behaves aggressively by its repeat recurrence. The therapeutic options are not standardized, one went for transphenoid hypophysectomy, another one is in conservative approach due to other more debilitating disease, and the recurrence case is pending for gamma knife treatment option after recent operation to relieve the optical symptoms There fore, the clinical importance is determined mainly by the size in anatomic image for local invasion potentials, evaluating the functional status and to rule out jeopardy from other much rare malignancy. Clinical approach may be based on incidentaloma that may usually follow a benign course, and baseline evaluation and observation over time can be the initial steps

Septic Arthritis of Hip Joint Causing Avascular Necrosis of Femoral Head in a 4-year-old Girl: A Case Report with Findings of Tc-99m MDP Three Phase Bone Scan

Septic (infectious) arthritis refers to invasion of synovial space by microbes and is a clinical emergency. Due to hyperemia of synovial vessels, the characteristic finding of three phase bone scan is increased tracer activity around the involved joint in all three phases. However, when there is prominent effusion (pus) inside the synovial cavity, tamponade of subsynovial vessels occurs, followed by avascular necrosis of intra-capsular bony structures if without urgent decompression. In this situation, the scintigraphic findings of three phase bone scan may turn to be intra-capsular photopenia in all three phases. We report a 4-year-old girl with fever, left hip pain, elevated CRP and ESR. The three phase bone scan showed intra-capsular photopenia of left hip in all three phases. Septic arthritis of left hip joint with prominent joint effusion (pus) and high intracapsular pressure were confirmed by arthrotomy. Avascular necrosis of left femoral head developed despite of the operation and antibiotic treatment. For early identification and proper treatment, it is important for nuclear medicine physicians and clinical doctors to be familiar with these important scintigraphic findings in septic arthritis.

Manifestations of 201TI Myocardial Single Photon Emission Computed Tomography in Patients with Coronary Fistula

Background: Coronary fistula is a congenital anomaly resulting in steal phenomenon of coronary blood flow, which may result in clinical symptoms and/or signs of coronary artery disease (CAD), including angina pectoris, myocardial ischemia, and congestive heart failure. The purpose of this study is to do a retrospective analysis of myocardial ischemia in 201TI images in patients with coronary fistulae. Methods: From September, 1992 to December, 2006, 26,758 cases underwent coronary angiography in our hospital and 58 of them (0.22%, 32 male; mean age 62±14, range from 35 to 87 years old), with chest pain and/or chest tightness underwent stress test for CAD. All patients received dipyridamole as pharmacological stress. All patients were followed by image acquisitions done immediately after stress and 4 h later. Results: All patients revealed coronary fistula by coronary angiography. Origin, drainage site, and diameter (large fistula ≥ 10 mm, small fistula ＜ 10 mm) of each fistula were recorded. Fifty seven patients (98%) had 201Tl perfusion defects in either reverse [R], partial reverse [PR], or reverse redistribution [RR] patterns. In the 201TI SPECTs, 82 abnormal perfusion areas were found including 52R (63%), 21PR (26%), and 9RR (11%). In all coronary fistulae, 64% (28/44) in LAD could see 201Tl perfusion defects in anterior, septal, and/or apical areas. In addition, 71% (5/7) in LCX could detect defects in lateral or inferior areas, and 70% (14/20) in RCA could detect defects in inferior and/or lateral areas. In fistulae without 201TI perfusion defect in corresponding territories, micro-fistulae were noted in 81% (13/16) of fistulae in LAD, 100% (3/3) of fistulae in LCX, and 83% (5/6) of fistulae in RCA. Conclusions: Myocardial ischemia with abnormal 201TI perfusion image can be detected in large portion of patients with coronary fistulae. Coronary fistulae with ischemia in 201TI perfusion images also can be associated with chest pain and/or chest tightness. The absence of 201TI perfusion defect in patients with coronary fistula may be due to micro-fistula without evident steal phenomenon of coronary blood flow.

18F-FDG PET and (superscript 99m)Tc-MDP Bone Scintigraphy in the Detection of Bony Metastasis from Medullary Thyroid Cancer: A Case Report

A 52-year-old man with history of medullary thyroid cancer (MTC) received total thyroidectomy and left neck lymph node dissection six years ago and then received wide excision for right chest wall metastases one month later. After operation, he received (superscript 99m)Tc-MDP bone scintigraphy and 18F-fluorodeoxyglucose positron emission tomography (FDG PET) for follow up. The bone scintigraphy revealed only a limited number of metastatic bony lesions. However, in contrast with bone scintigraphy, FDG PET showed wide-spread multiple metastatic bony lesions, much more than that shown by bone scintigraphy. The difference of imaging mechanism and morphologic characteristics of bony metastasis from MTC might attribute to the discrepancy in diagnostic sensitivity in MTC with bone metastasis between FDG PET and bone scintigraphy. As compared with bone scintigraphy, FDG-PET scan showed higher sensitivity for the detection of bony metastasis from medullary thyroid cancer.

Manifestations of (superscript 201)Tl Myocardial Single Photon Emission Computed Tomography in Patients with Myocardial Bridge

Background: Myocardial bridge (MB) is an congenital coronary anomaly resulting in systolic narrowing of coronary artery. It may be seen occasionally during coronary angiography (CAG) examinations and may cause clinical symptoms and/or signs of coronary artery disease (CAD). The symptoms/signs include angina pectoris, myocardial infarction, vasospasm, cardiac arrythmia, and sudden cardiac death. Few previous reports stated about the (superscript 201)TI perfusion defects noted in patients with MB, which probably imply the evidence of myocardial ischemia. The purpose of this study is to do a retrospective analysis of (superscript 201)TI images in patients with MB. Methods: From July, 2000 to June, 2003, 63 patients (30 male; mean age 57±10, and range from 33 to 80 years old), with chest pain and/or chest tightness underwent stress test for CAD. Six patients underwent treadmill exercise with Bruce protocol and 57 patients received dipyridamole as pharmacological stress. All patients were followed by image acquisitions done immediately after stress and 4 h later. All underwent CAG subsequently to identify the severity of CAD. Results: In all of the 63 patients, CAG revealed MB. Fifty patients had MB in left descending artery (LAD) (40 at mid portion; 8 at distal portion; 2 at mid and distal portion), 4 in left circumflex artery (LCX), and 1 in right coronary artery (RCA). Seven patients had MB in both LAD and LCX, and 1 patient had MB in both LAD and RCA. Sixty patients (95%) had (superscript 201)TI perfusion defects in either reverse (R), partial reverse (PR), or reverse redistribution (RR) patterns. In the abnormal (superscript 201)TI SPECTs, 103 abnormal perfusion areas were found including 57 R (55%), 40 PR (39%), and 6 RR (6%). In all vessels with MB, 48 (83%) in LAD could see (superscript 201)TI perfusion defects in anterior, septal, and/or apical areas. In addition, 6 of 11 (55%) in LCX could detect defects in lateral or inferior areas, and 2 of 2 (100%) in RCA could detect defects in inferior areas. Conclusions: Myocardial ischemia with abnormal (superscript 201)TI perfusion image can be detected in most patients with MB. MB with ischemic evidence in (superscript 201)TI perfusion image also may be associated with chest pain and/or chest tightness in our patients. (superscript 201)TI perfusion defect may be presented with R, PR, or RR in patients with MB. The significance of three different perfusion defects patterns (R, PR, and RR) may represent the various severity of perfusion insufficiency induced by MB.