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Annals of Nuclear Medicine (v.24, #8)

Recent developments and future prospects of SPECT myocardial perfusion imaging by Maseeh Uz Zaman; Ibrahim Hashmi; Nosheen Fatima (pp. 565-569).

Myocardial perfusion SPECT imaging is the most commonly performed functional imaging for assessment of coronary artery disease. High diagnostic accuracy and incremental prognostic value are the major benefits while suboptimal spatial resolution and significant radiation exposure are the main limitations. Its ability to detect hemodynamic significance of lesions seen on multidetector CT angiogram (MDCTA) has paved the path for a successful marriage between anatomical and functional imaging modalities in the form of hybrid SPECT/MDCTA system. In recent years, there have been enormous efforts by industry and academia to develop new SPECT imaging systems with better sensitivity, resolution, compact design and new reconstruction algorithms with ability to improve image quality and resolution. Furthermore, expected arrival of Tc-99m-labeled deoxyglucose in next few years would further strengthen the role of SPECT in imaging hibernating myocardium. In view of these developments, it seems that SPECT would enjoy its pivotal role in spite of major threat to be replaced by fluorine-18-labeled positron emission tomography perfusion and glucose metabolism imaging agents.

Keywords: Solid-state detector; CZT; Iterative reconstruction; Multi-pinhole collimator; Tc-99m-labeled deoxyglucose

Efficacy of conventional whole-body ¹⁸F-FDG PET/CT in the incidental findings of parotid masses by Hui-Chun Wang; Chuan-Tao Zuo; Feng-Chun Hua; Zhe-Min Huang; Hai-Bo Tan; Jun Zhao; Yi-Hui Guan (pp. 571-577).

The objective of this study was to evaluate the incidence of incidental parotid masses with conventional whole-body ¹⁸F-deoxyglucose (FDG) PET/CT and assess the ability of PET/CT to characterize these unexpected parotid lesions.Fifty eight incidental findings of parotid masses with routine FDG PET/CT whole-body scan were reviewed in this retrospective analysis, which were selected from the patients without any known or suspected parotid disease in our PET center, from June 2005 to May 2009. 51 cases were operated or underwent a biopsy after a short-term PET/CT study; the remaining 7 cases had a follow-up. Parotid mass that showed both noncontrast CT (irregular shape and blurry border) and PET malignant features (high FDG uptake, SUV_max > 3.0) was considered as positive for malignancy. Correlation of FDG PET/CT with histology or follow-up outcome was performed.Fifty eight unexpected findings of parotid masses accounted for 0.3% of the total cases in 4 years, including 11 (19.0%) malignant tumors and 47 (81.0%) benign lesions. 13 lesions manifested single nodule with malignant CT features and intense FDG activity, of which 6 were proved to be malignant; thus, sensitivity and positive predictive values were 54.5% (6 of 11) and 46.2% (6 of 13), respectively. 45 lesions showed either single nodule with benign CT features, or a low FDG uptake (SUV_max ≤ 3.0), of which 40 were true negatives; therefore, specificity and negative predictive values were 85.1% (40 of 47) and 88.9% (40 of 45), respectively. All parotid masses except 9 benign and 1 malignant showed a high FDG uptake. Compared with SUV only, combined interpretation of PET and CT results displayed a lower sensitivity (90.9–54.5%), but a higher specificity (19.1–85.1%) and a higher overall accuracy.Whole-body FDG-PET/CT at the time of surveying the entire body condition is helpful for detecting the asymptomatic parotid masses. Combined noncontrast CT is an essential evidence for improving the diagnostic accuracy of FDG-PET/CT for parotid masses.

Keywords: FDG; Incidental findings; Parotid masses; PET/CT; SUV_max

¹⁸F-FAMT uptake correlates with tumor proliferative activity in oral squamous cell carcinoma: comparative study with ¹⁸F-FDG PET and immunohistochemistry by Go Miyashita; Tetsuya Higuchi; Noboru Oriuchi; Yukiko Arisaka; Hirofumi Hanaoka; Hideyuki Tominaga; Satoshi Morita; Mitsuyuki Miyakubo; Tomohiro Ishikita; Yoshiki Nakasone; Akihide Negishi; Satoshi Yokoo; Keigo Endo (pp. 579-584).

l-3-[¹⁸F]-fluoro-α-methyl tyrosine (FAMT) is transported into cancer cells by l-type amino acid transporter 1 (LAT1). The purpose of the present study is to correlate the uptake of FAMT and FDG with the cellular proliferative activity measured by the Ki-67 labeling index (Ki-67 LI) in oral squamous cell carcinoma (OSCC).Twenty-five patients with OSCC were enrolled in this study. Both FAMT-PET and FDG-PET were performed within 4 weeks before surgery in all cases. The uptake of FAMT and FDG was compared by semiquantitative analysis with maximal standardized uptake values (SUVmax) of the primary tumors. Ki-67 LI of the tumors was analyzed by immunohistochemical staining and correlated with the clinicopathologic variables and the uptake of PET tracers.For primary tumor detection, FAMT-PET exhibited a sensitivity of 84%, whereas that of FDG-PET was 88%. In all visible lesions, mean FDG uptake determined by average SUVmax was 9.7 (range 4.2–15.9) and mean FAMT uptake was 3.5 (range 1.3–8.5). The SUVmax of FAMT tended to show a better correlation with Ki-67 LI (r = 0.878) than that of FDG (r = 0.643).Uptake of FAMT correlated with cellular proliferation of OSCC. FAMT-PET may be a useful procedure to evaluate tumor proliferation of OSCC.

Keywords: l-3-[¹⁸F]fluoro-α-methyl tyrosine; ¹⁸F-FDG; Oral squamous cell carcinoma; Ki-67; LAT1

A simple table lookup method for PET/CT partial volume correction using a point-spread function in diagnosing lymph node metastasis by Yuichi Sakaguchi; Noriko Mizoguchi; Tatsuya Mitsumoto; Katsuhiko Mitsumoto; Kazuhiko Himuro; Nobuyoshi Ohya; Koichiro Kaneko; Shingo Baba; Koichiro Abe; Yoshihiko Onizuka; Masayuki Sasaki (pp. 585-591).

We evaluated the partial volume effect in PET/CT images and developed a simple correction method to address this problem.Six spheres and the background in the phantom were filled with F-18 and we thus obtained 4 different sphere-to-background (SB) ratios. Thirty-nine cervical lymph nodes in 7 patients with papillary thyroid carcinoma (15 malignant and 24 benign) were also examined as a preliminary clinical study. First, we developed recovery coefficient (RC) curves normalized to the maximum counts of the 37-mm sphere. Next, we developed a correction table to determine the true SB ratio using three parameters, including the maximum counts of both the sphere and background and the lesion diameter, by modifying the approximation formula of the RC curves including the point-spread function correction. The full width at half maximum in this formula is estimated with the function of the SB ratio.In the phantom study, a size-dependent underestimation of the radioactivity was observed. The degree of decline of RC was influenced by the SB ratio. In preliminary clinical examination, the difference in the SUV_max between malignant and benign LNs thus became more prominent after the correction. The PV correction slightly improved the diagnostic accuracy from 95 to 100%.We developed a simple table lookup correction method for the partial volume effect of PET/CT. This new method is considered to be clinically useful for the diagnosis of cervical LN metastasis. Further examination with a greater number of subjects is required to corroborate its clinical usefulness.

Keywords: PET/CT; Lymph node metastasis; Point-spread function; Partial volume effect; Recovery coefficient

Evaluation of FDG uptake in pulmonary hila with FDG PET/CT and contrast-enhanced CT in patients with thoracic and non-thoracic tumors by Gonca Kara Gedik; Pelin Ozcan Kara; Taylan Kara; Oktay Sari; Fatih Kara (pp. 593-599).

Fluorine-18 fluorodeoxyglucose (FDG) uptake is frequently observed in lung hilus. This finding causes difficulties during the interpretation. Our objective was to evaluate the features of FDG uptake in lung hilus associated with benign or malignant etiology in patients with thoracic and non-thoracic tumors.We retrospectively evaluated the files of 1172 patients who had undergone FDG positron emission tomography (PET)/computed tomography (CT) examination between January 2008 and June 2009. Forty-eight patients (21 males, 27 females, age range 12–80 years, mean 60.9 ± 15.82 years) with either unilateral or bilateral hilar FDG uptake and who had thorax contrast-enhanced computed tomography (CECT) performed within 1 month of the FDG PET/CT scan were enrolled in the study. Characteristics of FDG uptake were classified according to the pathology and CECT or PET/CT follow-up over 12 months.The characteristics of 71 hilar regions with FDG uptake could be classified. In 30 of 71 (42.3%) hilar regions, FDG uptake was considered to be physiological because no lymph node was observed on CECT. In 19 of 71 (26.8%), FDG uptake was secondary to benign lymph nodes and in 22 (30.9%) to malignant lymph nodes. Significant differences were observed between benign and malignant lymph nodes for SUVhilus and SUVhilus/SUVliver ratio. Using 4.49 as the cut-off value for SUVhilus, a sensitivity of 85.7% and a specificity of 86.4% were achieved (area under curve, AUC: 0.956). For SUVhilus/SUVliver ratio, sensitivity and specificity to detect malignant lymph nodes were 77.6 and 77.3% (AUC: 0.885), respectively, at a cut-off value of 1.75.SUVhilus and SUVhilus/SUVliver ratio were found to be significant parameters for determining malignancy in lung hilus. Combined interpretation with CECT is warranted during the evaluation of lung hilus with FDG PET/CT.

Keywords: Contrast-enhanced computed tomography; FDG; Lung hilus; Lymph node; Positron emission tomography

Lymphoscintigraphy for sentinel lymph node mapping in Japanese patients with malignant skin neoplasms of the lower extremities: comparison with previously investigated Japanese lymphatic anatomy by Hiroyuki Miura; Shuichi Ono; Morio Nagahata; Koichi Shibutani; Shinya Kakehata; Kohei Morimoto; Hiroko Seino; Akihisa Kakuta; Masahiko Aoki; Yoshiomi Hatayama; Hideo Kawaguchi; Yoshihiro Takai; Yoshinao Abe; Takahide Kaneko; Daisuke Sawamura; Katsumi Hanada (pp. 601-608).

Lymph nodes (LN) and lymphatic drainage were identified by lymphoscintigraphy using ^99mTc-phytate in order to map the sentinel lymph nodes (SLNs) in patients with malignant skin neoplasms of the lower extremities, and to compare the results with an atlas of Japanese lymphatic anatomy.Sentinel lymphoscintigraphs of 18 patients with malignant skin neoplasms of the lower extremities (9 men, 9 women; age range 45–84 years, mean age 66 years) were analyzed retrospectively, and the LNs detected were identified as SLNs or secondary nodes.The patterns of lymphatic drainage were divided into three different categories: (1) initial drainage into inguinal LN without visualization of popliteal LNs (inguinal type), (2) initial drainage into popliteal LNs and then into intrapelvic LNs (popliteal type), and (3) initial drainage into both popliteal and inguinal LNs (inguinal and popliteal type). More than half of the cases were the inguinal and popliteal type, as both inguinal and popliteal LNs were identified as SLNs. In the cases in which the hallux and its surrounding area were injected, all were the inguinal type and popliteal LNs were not visualized. In one case, only dynamic images detected lymphatic drainage without visualization of popliteal LNs. In contrast to the previously published literature on Japanese lymphatic anatomy, SLN lymphatic drainage from the skin of the lower extremities was wide and overlapping in many areas. However, in agreement with currently accepted anatomy, only the great saphenous lymphatic vessel drained the skin of the hallux and its surrounding area. The present results suggest that it is important to confirm lymphatic drainage in order to identify SLNs in the lower extremities.The patterns of lymphatic drainage from the skin of the foot were divided into three different categories. In contrast to previously published Japanese lymphatic anatomy, lymphatic drainage from the skin of the lower extremities was wide and overlapping in many areas. However, only the great saphenous lymphatic vessel drained the skin of the hallux and its surrounding area in agreement with currently accepted Japanese lymphatic anatomy. It is important to confirm lymphatic drainage to identify SLNs in the lower extremities.

Keywords: Lymphoscintigraphy; Sentinel lymph node; Dynamic scan; Lower extremity; Japanese lymphatic anatomy

Judicious use of recombinant TSH in the management of differentiated thyroid carcinoma by Muhammad Umar Khan; Mohammad Khalid Nawaz; Mazhar Ali Shah; Aamir Ali Syed; Amina Iqbal Khan (pp. 609-615).

To evaluate the feasibility of using recombinant human TSH (rhTSH) in conjunction with ¹³¹I to treat patients with differentiated thyroid carcinoma.Between July 2003 and April 2009, 14 patients [mean age, 39.1 years (range 14–71 years)], of whom seven were treated for remnant ablation and seven for irresectable or metastatic disease, received rhTSH-aided ¹³¹I therapy. None had an adequate rise in TSH. The mean ¹³¹I dosage administered was 5206.3 MBq. Baseline thyroglobulin/anti-thyroglobulin (Tg/anti-Tg) and TSH levels were documented. rhTSH (0.9 mg) was given intramuscularly on days 1 and 2, and TSH levels were recorded. ¹³¹I was given when the TSH level rose to >30 μIU/ml. Tg/anti-Tg levels were measured at 3-month intervals. A ¹³¹I whole-body scan (¹³¹I scan) was performed 6 or 12 months after treatment.The baseline median valid Tg and TSH levels were 76.2 ng/ml (range 14.1 to >30000) and 3.63 μIU/ml (range 1.36–11.0), respectively. The rise in TSH level was 34.8–96.9 μIU/ml after the first rhTSH injection and 33.1 to >75 μIU/ml after the second injection. The post-therapy ¹³¹I scan showed uptake at disease sites in all patients, indicating the initial empirical adequacy of treatment. Follow-up ¹³¹I scan was positive for four patients, but negative for three of these patients after subsequent therapy. Complete resolution of disease was seen in eight patients and partial resolution in four after 3 months of therapy; one had stable disease; and in one patient with progressive disease, complete resolution was achieved after repeated ¹³¹I doses with thyroxine withdrawal. After a median follow-up of 39.2 months, all patients were alive and no disease recurrence was observed. The overall response rate at 3 months was 86% and had improved to 93% at the time of this review. The final ablation rate in seven patients was 100%. Apart from notable neck swelling in four patients, which was responsive to medication, and headache in two patients, no significant short-term side-effects of therapy were seen.In our setting, the use of rhTSH-aided ¹³¹I ablation and treatment was safe and effective.

Keywords: Recombinant human TSH; Differentiated thyroid carcinoma; Radioactive iodine ablation; rhTSH-aided radioactive iodine treatment

Complete regression of multiple painful bone metastases from hepatocellular carcinoma after administration of strontium-89 chloride by Naohisa Suzawa; Koichiro Yamakado; Haruyuki Takaki; Atsuhiro Nakatsuka; Kan Takeda (pp. 617-620).

A 69-year-old man received strontium-89 chloride intravenous injection to relieve uncontrollable pain from multiple hepatocellular carcinoma bone metastases. Pain was resolved 3 months later without opioid analgesics. Multiple bone metastases showed complete regression 4 months later. The patient lived for 1 year without recurrence of bone metastasis.

Keywords: Strontium-89 chloride; Hepatocellular carcinoma; Bone metastasis; Regression

Clinical benefit of SPECT/CT for follow-up of surgical treatment of osteochondritis dissecans by Praveen Konala; Farhad Iranpour; Anna Kerner; Helmut Rasch; Niklaus F. Friederich; Michael T. Hirschmann (pp. 621-624).

We present the case of a 17-year-old ice-hockey player, who complained about persistent left medial knee pain having undergone a refixation of a grade III osteochondritis dissecans with biodegradable pins, a reconstruction of the anterior cruciate ligament (ACL) and a medial meniscal repair 1 year previously. Sequential MRIs performed 8 and 12 months after surgery were inconclusive, and failed to show the insufficient integration of the osteochondral fragment. Combined single photon emission and conventional computerized tomography (SPECT/CT) clearly revealed the cause of the patient’s persistent knee problems—the osteochondral fragment had not integrated. SPECT/CT may hold great clinical value for symptomatic patients who have previously undergone treatment for osteochondral lesions, and it should be considered as alternative diagnostic imaging modality.

Keywords: SPECT/CT; Knee; Osteochondritis dissecans; Clinical value

Assessment of diastolic function using 16-frame ²⁰¹Tl-gated myocardial perfusion SPECT by Shinro Matsuo (pp. 625-625).

Reply to ‘Assessment of diastolic function using 16-frame ²⁰¹Tl-gated myocardial perfusion SPECT’ by Shigeki Nagamachi (pp. 627-627).

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Annals of Nuclear Medicine (v.24, #8)

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Annals of Nuclear Medicine (v.24, #8)