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Annals of Nuclear Medicine (v.25, #4)

New software for raw data mask processing increases diagnostic ability of myocardial SPECT imaging by Ryo Tanaka; Katsunori Yoshioka; Kazue Seino; Muneo Ohba; Tomoharu Nakamura; Katsuhiko Shimada (pp. 231-239).

Increased activity of myocardial perfusion tracer technetium-99m in liver and hepatobiliary system causes streak artifacts, which may affect clinical diagnosis. We developed a mask-processing tool for raw data generated using technetium-99m as a myocardial perfusion tracer. Here, we describe improvements in image quality under the influence of artifacts caused by high accumulation in other organs.A heart phantom (RH-2) containing 15 MBq of pertechnetate was defined as model A. Model B was designed in the same phantom containing ten times of cardiac radioactivity overlapping with other organs. Variance in the vertical profile count in the lower part of the myocardial inferior wall and in the myocardial circumferential profile curve were investigated in a phantom and clinical cases using our raw data masking (RDM) software.The profile variances at lower parts of myocardial inferior walls were 965.43 in model A, 1390.11 in model B and 815.85 in B-RDM. The mean ± SD of myocardial circumferential profile curves were 83.91 ± 7.39 in model A, 69.61 ± 11.45 in model B and 82.68 ± 9.71 in model B-RDM. For 11 clinical images with streak artifacts, the average of the variance significantly differed between with and without RDM (3.95 vs. 21.05; P < 0.05). For 50 clinical images with hepatic accumulation artifacts, the average of the variance on vertical profiles on images with and without RDM significantly differed (5.99 vs. 15.59; P < 0.01). Furthermore, when a segment with <60% uptake in polar maps was defined as abnormal, the average extent score of 1 h (Tc-1h), 5 min of RDM (Tc-0h-RDM) and 5 min of non-RDM (Tc-0h-non-RDM) were 2.25 ± 3.12, 2.35 ± 3.16, and 1.37 ± 2.41, respectively. Differences were significant between Tc-1h and Tc-0h-non-RDM (P < 0.005) but not between Tc-1h and Tc-0h-RDM.Batch processing was enabled in all frames by shifting the myocardium to the center of rotation using this software. The waiting time between infusion and image acquisition should be decreased, thus reducing patient burden and improving the diagnostic ability of the procedure.

Keywords: ^99mTc-sestamibi; ^99mTc-tetrofosmin; Streak artifacts; Mask processing

Positive correlations between tumor uptake on FDG PET and energy expenditure of patients with esophageal cancer by Atsushi Mitamura; Tomohiro Kaneta; Go Miyata; Kentaro Takanami; Tomomichi Hiraide; Hiroshi Fukuda; Shoki Takahashi; Susumu Satomi (pp. 241-246).

Cancer patients are prone to clinical malnutrition; moreover, the energy expenditure in patients with certain cancers is higher than that in healthy individuals, rendering their nutritional management a challenging issue. We hypothesized that 2-deoxy-2-[¹⁸F]fluoro-d-glucose (FDG) uptake on positron emission tomography (PET) may be related to the energy expenditure and analyzed the FDG uptake and energy expenditure in esophageal cancer patients to clarify this.Esophageal cancer patients [n = 13, 10 males and 3 females, age 66.5 ± 8.9 (51–82) years] were evaluated for FDG uptake using PET. The resting energy expenditure (REE) and basal energy expenditure (BEE) were calculated using indirect calorimetry and the Harris–Benedict formula, respectively. Regression analyses were performed to compare the parameters of imaging and energy expenditure.Positive correlations were found between tumor uptake on FDG PET and the parameters of energy expenditure. Among them, the correlations between SUV_max and the ratio of REE to BEE (REE/BEE, r = 0.59; p = 0.035) and between SUV_max and the difference between REE and BEE (REE − BEE, r = 0.58; p = 0.036) were moderate and statistically significant. Further, the correlation between tumor uptake expressed as a percentage (%TU) and REE/BEE was mild (r = 0.51) but not significant (p = 0.07), while that between %TU and REE–BEE was weak (r = 0.42) and not significant (p = 0.15).Significant positive correlations between SUV_max on FDG PET and energy expenditure were noted in our study; we consider that these results may aid in determining the nutritional management for esophageal cancer patients.

Keywords: FDG PET; Nutrition; Esophageal cancer; Energy expenditure

¹⁸F-FDG uptake on PET helps predict outcome and response after treatment in unresectable thymic epithelial tumors by Kyoichi Kaira; Haruyasu Murakami; Satoru Miura; Rieko Kaira; Hiroaki Akamatsu; Madoka Kimura; Akira Ono; Asuka Tsuya; Yukiko Nakamura; Tateaki Naito; Toshiaki Takahashi; Masahiro Endo; Nobuyuki Yamamoto (pp. 247-253).

Positron emission tomography (PET) with fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) has been studied in thymic epithelial tumors. We evaluated the usefulness of ¹⁸F-FDG PET for monitoring after treatment in unresectable thymic epithelial tumors.Twelve patients with unresectable/metastatic thymic epithelial tumors underwent PET study with ¹⁸F-FDG before and after chemotherapy or radiotherapy. Response and survival were analyzed according to the ratio of the peak standardized uptake value (SUV) of the tumor to the mean SUV of the mediastinum (T/M ratio).Partial response (PR) evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) was noted in 4 (33%) of 12 patients, and partial metabolic response (PMR) was observed in 6 (50%) of 12 patients. PR was observed in 4 of 6 patients with PMR. In 6 patients with any response, the T/M ratio at post-treatment was significantly lower than at baseline (p = 0.0017). In 6 patients with stable disease (SD), stable metabolic disease (SMD) was observed in 5 by use of ¹⁸F-FDG PET. No statistically significant difference of ¹⁸F-FDG uptake between at baseline and post-therapy was observed in 6 patients with SD (p = 0.4157) and SMD (p = 0.8419). Although the overall survival after treatment showed no statistically significant difference between PMR and SMD or progressive metabolic disease in the whole group of patients including thymoma, a statistically significant difference in the overall survival was observed between 5 patients with PMR and 5 patients with non-PMR (p = 0.0280).Our preliminary study suggests that ¹⁸F-FDG PET is useful for monitoring response and outcome after treatment in unresectable thymic epithelial tumors.

Keywords: ¹⁸F-FDG PET; Thymic epithelial tumor; Monitoring; Therapy response; Metabolic response

Regional cerebral blood flow in healthy volunteers measured by the graph plot method with iodoamphetamine SPECT by Kazunari Ishii; Takafumi Uemura; Naokazu Miyamoto; Toshiki Yoshikawa; Toshiaki Yamaguchi; Tatsuhiko Ashihara; Yukihiro Ohtani (pp. 255-260).

The graph plot method, a technique that uses N-isopropyl-¹²³I-p-iodoamphetamine (IMP) and single photon emission computed tomography (SPECT) for non-invasive measurement of regional cerebral blood flow (CBF), has been developed and applied in the clinical setting, although it has been performed without obtaining normal CBF values in normal, healthy subjects. The aim of this study was to measure normal regional CBF in older healthy subjects with IMP SPECT and the graph plot method.Eleven healthy volunteers (mean age: 63.5 ± 8.9 years; six males and five females) were recruited and regional CBF was measured using IMP SPECT and the graph plot method.The averaged global CBF was 45.4 ml/100 g/min. The distribution of regional CBF was almost homogenous in the cortices. There was no significant correlation between the global CBF and age in subjects aged 50–80 years.We used the IMP graph plot method to measure regional CBF in normal healthy subjects, without arterial blood sampling, and obtained compatible CBF values. This method is non-invasive and convenient for determination of regional CBF in the clinical setting.

Keywords: Cerebral blood flow; SPECT; Graph plot method; Iodoamphetamine

Relationship of detection rate of PET cancer screening examinees and risk factors: analysis of background of examinees by Koji Shibata; Masami Arai; Masaaki Matsuura; Kimiichi Uno; Teruhiko Yoshida; Toshimitsu Momose; Kuni Ohtomo (pp. 261-267).

PET cancer screening is performed widely in Japan as opportunistic screening, but no study has focused on the correlation with various cancer risk factors and the seeking bias of examinees and cancer detection rate. Analyzing our large series of PET cancer screening data, correlations with cancer detection rates according to general cancer risk factors and PET detection survey were reviewed, and the selection bias of the medical examinees was determined.19189 examinees who underwent PET cancer screening were enrolled. Using logistic-regression analysis, we analyzed correlations between smoking history/drinking history/cancer family history and detection rates of thyroid cancer/breast cancer/colorectal cancer/lung cancer, which are the main malignancies detected in PET cancer screening. In addition, we evaluated seeking bias of examinees, analyzing correlations between the presence of cancer risk factors and prior screening checkups at other institutions to our PET cancer screening using a matched case–control study.Cancer detection rates by FDG-PET were 1.17% (224/19189), being much higher than those of standard cancer mass screenings. In males, statistically significant correlations were seen between lung cancer and smoking, and between prostate cancer and a family history of prostate cancer, but not between the detection rates of three other types of cancer (thyroid cancer/lung cancer/colorectal cancer) and other cancer risk factors. In females, detection rates of four types of cancer (thyroid cancer/lung cancer/colorectal cancer/breast cancer) were significantly higher in the examinees without cancer risks, and subgroup analysis according to types of cancer did not indicate significant correlations either. The matched case–control study evaluating seeking bias indicated that a significant proportion of the examinees with cancer risks had undergone prior cancer screening at other institutions.Our study indicated that there was significant seeking bias for prior screening of examinees, with this accounting for the fact that this study did not find a significant correlation between cancer risks and cancer detection rates. The results of our study indicated that PET cancer screening can provide high cancer detection rates.

Keywords: PET cancer screening; Risk factors; Detection rate; Seeking bias

Clinical value of FDG-PET for preoperative evaluation of endometrial cancer by Tsuyoshi Suga; Yuji Nakamoto; Tsuneo Saga; Tatsuya Higashi; Yasuyo Hamanaka; Mitsuaki Tatsumi; Kohei Hayashida; Tadashi Hara; Ikuo Konishi; Shingo Fujii; Kaori Togashi (pp. 269-275).

Whole body positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) has been widely used in various malignancies, but the clinical value of FDG-PET for endometrial cancer has not been fully investigated. The purpose of this study was to evaluate the usefulness of FDG-PET for preoperative evaluation of endometrial cancer.Forty female patients suspected of having endometrial cancer were included in this study. All patients underwent an FDG-PET or PET/CT scan, and images were interpreted visually. The diagnostic performance in detecting the primary tumor, regional nodal status, and distant metastasis was determined. In addition, the usefulness of PET was assessed in terms of additional information and clinical impact for therapeutic management.Of 40 patients, 30 were histologically confirmed to have endometrial cancer. The patient-based sensitivity and specificity of FDG-PET for primary tumors were 83 and 100%, respectively, and 100 and 100%, respectively, for nodal metastases. There were 12 distant metastases in 6 patients and two second primary cancers in two patients, which were all accurately diagnosed by PET on a patient-basis. PET yielded 12 additional findings in 10 patients, and had a bearing on the therapeutic management of four patients, including one patient with recurrent breast cancer.FDG-PET had a reasonably high diagnostic accuracy in endometrial cancer. Although the number of cases with clinical impact was limited, additional information by PET was obtained in one-third of the cases.

Keywords: FDG-PET; Endometrial cancer; Preoperative evaluation

The usefulness of fully three-dimensional OSEM algorithm on lymph node metastases from lung cancer with ¹⁸F-FDG PET/CT by Kazumasa Inoue; Etsuo Moriya; Takayuki Suzuki; Yoshiko Ohnuki; Takashi Sato; Hideaki Kitamura; Tatsuya Sasaki; Masahiro Fukushi; Noriyuki Moriyama; Hirofumi Fujii (pp. 277-287).

This work assessed the usefulness of fully three-dimensional ordered subset expectation maximization (3D-OSEM) algorithm for lymph node (LN) metastases from lung cancer. 3D-OSEM images were evaluated by comparing them with those reconstructed by conventional algorithms, such as conventional OSEM algorithm (2D-OSEM) for 2D acquisition and Fourier rebinning plus conventional OSEM algorithm (FORE + OSEM) for 3D acquisition.In a phantom study, the contrast ratio, the image noise and the signal-to-noise ratio (SNR) were calculated, and the detectability and the image quality of these images were visually evaluated. In a clinical study, 14 patients suffering from lung cancer with LN metastases were evaluated. The image quality and the malignancy, and the detectability were visually evaluated.The contrast ratio was significantly improved using 3D-OSEM as compared with FORE + OSEM, and it was similar to 2D-OSEM. The image noise and SNR in 3D-OSEM images were significantly improved compared with those by other algorithms (p < 0.001). In the visual assessment, the image quality was significantly improved in 3D-OSEM images compared with those by 2D-OSEM and FORE + OSEM (p < 0.001, p = 0.001, respectively). In the clinical study, the image quality and the detectability of LN metastases were improved in 3D-OSEM images compared with those by FORE + OSEM (p < 0.001, p = 0.006, respectively), and image quality and detectability were similar to those of 2D-OSEM images.3D-OSEM algorithm successfully improved the diagnostic accuracy of LN metastases in 3D-PET tests.

Keywords: 3D-OSEM; FDG PET/CT; Lung cancer; Lymph node metastasis

Clinical significance of CT density-based, non-uniform photon attenuation correction of deep-inspiratory breath-hold perfusion SPECT by Kazuyoshi Suga; Munemasa Okada; Mitsue Kunihiro; Hideyuki Iwanaga; Naofumi Matsunaga (pp. 289-298).

The effect of computed tomography (CT) density-based, non-uniform photon attenuation correction (AC) on lung perfusion distribution and the clinical significance were evaluated.40 patients with pulmonary emphysema, 32 with pulmonary thromboembolism, 25 with lung cancer and 8 normal controls underwent deep-inspiratory breath-hold (DIBrH) Tc-99m-MAA perfusion SPECT, using a dual-head SPECT system and a respiratory tracking device. Scatter-corrected DIBrH SPECT was automatically co-registered with DIBrH CT. AC of DIBrH SPECT was performed using an attenuation coefficient map of a variable-effective linear coefficient calculated from CT pixel density of the co-registered DIBrH CT. The effect of AC on pulmonary perfusion was evaluated by comparison with uncorrected SPECT.After AC, lung perfusion in normal lungs was increased predominantly at deep lungs near the mediastinum and vertebrae and at the upper-middle lungs, with systematic increases of radioactivity (145 ± 28%) and significant enhancement of physiological gravitational ventral–dorsal gradient (P < 0.01). Throughout the lung diseases, AC significantly enhanced perfusion defect clarity and heterogeneity (P < 0.001), without noticeable artifacts. The correlation between perfusion heterogeneity and the lung diffusing capacity for carbon monoxide was significantly improved in patients with emphysema (P < 0.005).CT density-based, non-uniform AC of DIBrH perfusion SPECT provides better assessment of physiologic or impaired perfusion distributions in normal and lung diseases.

Keywords: Single photon emission computed tomography (SPECT); Pulmonary perfusion; Fusion images; Attenuation correction

Differential uptake of ¹⁸F-FDG in patients with synchronous lung cancers by Shaunak Navalkissoor; Teresa Szyszko; Sheila Rankin; Gopinath Gnanasegaran (pp. 299-302).

¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET/CT) has developed into the standard of care for investigating patients with non-small cell lung cancer (NSCLC) to determine the optimal treatment. However, although the majority of patients with NSCLC do have intense uptake of tracer, false negatives do occur and should be considered. We report cases of patients that have synchronous NSCLCs. In both cases, there was intense uptake of FDG in one tumour type, with very low grade uptake in the separate tumour. Histology confirmed separate lung malignancies, demonstrating that differential FDG uptake may not always be inflammatory and should be considered to have a separate malignant aetiology.

Keywords: FDG; NSCLC; Synchronous; False negative

A case of diffuse-type primary hepatic lymphoma mimicking diffuse hepatocellular carcinoma by Koichiro Kaneko; Akihiro Nishie; Fumitou Arima; Tsuyoshi Yoshida; Ken Ono; Junichi Omagari; Hiroshi Honda (pp. 303-307).

Primary hepatic lymphoma (PHL) is a very rare disease, especially in the diffuse type. We report a case of a middle-aged man with hepatitis C virus infection who developed diffuse-type PHL mimicking diffuse hepatocellular carcinoma (HCC). Contrast-enhanced computed tomography (CT) and magnetic resonance imaging showed diffusely infiltrated hypovascular lesions throughout the liver, but no intrahepatic portal venous thrombus was observed. Diffusion-weighted imaging and ¹⁸F-FDG positron emission tomography/CT, respectively, showed a very low apparent diffusion coefficient value and high FDG uptake. These findings were more suggestive of diffuse-type PHL than diffuse HCC. Liver biopsy examination confirmed a diagnosis of diffuse large B-cell lymphoma. Systemic staging revealed no evidence of nodal or bone marrow involvement, so PHL was diagnosed. The patient was treated with chemotherapy and achieved complete remission. We suggest that a combination of image modalities may enable differentiation of diffuse-type PHL from diffuse HCC.

Keywords: Diffuse-type primary hepatic lymphoma; ¹⁸F-FDG-PET/CT; Diffusion-weighted MRI; Diffuse hepatocellular carcinoma

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Annals of Nuclear Medicine (v.25, #4)