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Annals of Nuclear Medicine (v.27, #1)

Predictive value of 3′-deoxy-3′-[¹⁸F]fluorothymidine positron emission tomography/computed tomography for outcome of carbon ion radiotherapy in patients with head and neck mucosal malignant melanoma by Masayuki Inubushi; Tsuneo Saga; Mitsuru Koizumi; Ryo Takagi; Azusa Hasegawa; Masashi Koto; Masaru Wakatuki; Takamichi Morikawa; Kyosan Yoshikawa; Katsuyuki Tanimoto; Toshimitsu Fukumura; Shigeru Yamada; Tadashi Kamada (pp. 1-10).

The purpose of this prospective study was to assess the prognostic value of 3′-deoxy-3′-[¹⁸F]fluorothymidine (FLT) positron emission tomography/computed tomography (PET/CT) for the outcome of carbon ion radiotherapy (CIRT) in patients with mucosal malignant melanoma (MMM) of the head and neck.Thirteen patients (69 ± 13 years) with histologically proven MMM tumor were enrolled. CIRT was performed with a total dose of 57.6–64.0 gray equivalents per 16 fractions over a period of 4 weeks. FLT-PET/CT was performed before and again 1 month after CIRT. Tumor FLT uptake was quantitatively assessed using the maximum standardized uptake value (SUV_max). FLT-PET parameters [pre-CIRT SUV_max, post-CIRT SUV_max, and the reduction rate (RR)] and clinical parameters [age, gender, tumor site, tumor status, gross tumor volume (GTV), and regional lymph node involvement] were evaluated in relation to survival estimates. The follow-up period was 16.1 ± 5.9 months for 9 deceased patients, and 36.7 ± 7.9 months for 4 survivors.Pre-CIRT SUV_max of ≥4.3, age of ≥80 years old, sinonasal cavity tumor site, and GTV of ≥39 mL were found to be statistically significant prognostic factors for better overall survival. Pre-CIRT SUV_max of ≥5.0, age of ≥80 years old, sinonasal cavity tumor site, and the absence of regional lymph node involvement were statistically significant prognostic factors for better metastasis-free survival. RR of ≥35 % and GTV of <73 mL were predictive of better local control.The present study indicated for the first time that in patients with the head and neck MMM, FLT-PET/CT imaging was useful for predicting the therapeutic outcome of CIRT. Our results will contribute to the establishment of an effective staging system for MMM based on prognostic factors, depending on treatment choice.

Keywords: F18 Fluorothymidine (FLT); Positron-emission tomography and computed tomography (PET/CT); Mucosal malignant melanoma (MMM); Head and neck neoplasms; Carbon ion radiotherapy (CIRT)

Performance of a semiconductor SPECT system: comparison with a conventional Anger-type SPECT instrument by Yasuyuki Takahashi; Masao Miyagawa; Yoshiko Nishiyama; Hayato Ishimura; Teruhito Mochizuki (pp. 11-16).

The performance of a new single photon emission computed tomography (SPECT) scanner with a cadmium-zinc-telluride (CZT) solid-state semiconductor detector (Discovery NM 530c; D530c) was evaluated and compared to a conventional Anger-type SPECT with a dual-detector camera (Infinia).Three different phantom studies were performed. Full width at half maximum (FWHM) was measured using line sources placed at different locations in a cylindrical phantom. Uniformity was measured using cylindrical phantoms with 3 different diameters (80, 120, and 160 mm). Spatial resolution was evaluated using hot-rod phantoms of various diameters (5, 9, 13, 16, and 20 mm). Three different myocardial phantom studies were also performed, acquiring projection data with and without defects, and evaluating the interference of liver and gallbladder radioactivity. In a clinical study, the D530c employed list-mode raw data acquisition with electrocardiogram (ECG)-gated acquisition over a 10-min period. From the 10-min projection data, 1-, 3-, 5-, 7- and 10-min SPECT images were reconstructed.The FWHM of the D503c was 1.73–3.48 mm (without water) and 3.88–6.64 mm (with water), whereas the FWHM of the Infinia was 8.17–12.63 mm (without water) and 15.48–16.28 mm (with water). Non-uniformity was larger for the D530c than for the Infinia. Truncation artifacts were also observed with the D530c in a Φ160 mm phantom. The contrast ratio, as defined by myocardial defect/non-defect ratio, was better for the D530c than for the Infinia, and the influence from liver and gallbladder radioactivities was less. Quantitative gated SPECT (QGS) software demonstrated significant differences between data captured over a 10-min period, relative to those acquired over periods of <5 min; there was no difference between ejection fractions calculated using data capture for periods ≥5 min (p < 0.05).The D530c is superior to the Infinia, with regard to both spatial resolution and sensitivity. In this study, these advantages were confirmed by the myocardial phantom and in a clinical setting, using the QGS software.

Keywords: Semiconductor camera; Spatial resolution; Sensitivity; Myocardial SPECT

A novel PET scanner with semiconductor detectors may improve diagnostic accuracy in the metastatic survey of head and neck cancer patients by Toshiki Takei; Tohru Shiga; Yuichi Morimoto; Wataru Takeuchi; Kikuo Umegaki; Kazuki Matsuzaki; Shozo Okamoto; Keiichi Magota; Toshihiro Hara; Satoshi Fukuda; Nagara Tamaki (pp. 17-24).

Our research group developed new PET scanner with semiconductor detectors for high spatial resolution with low scatter noise. On head and neck cancer (HNC) surgery, FDG-PET may often provide false-positive findings in cervical node involvements. Accordingly, we assessed diagnostic accuracy using this new scanner in the HNC patients as compared with the conventional lutetium oxyorthosilicate (LSO) PET.We prospectively studied FDG imaging in 35 HNC patients by both semiconductor PET and LSO-PET. At 60 min after ¹⁸F-FDG injection, two PET scans were obtained using both scanners consecutively and in random order. Two nuclear medicine specialists scored FDG abnormalities using 5 point scale system for receiver operating characteristic (ROC) curve analysis.63 suspected of metastatic or recurrent lesions were evaluated and correlated by the final confirmation by pathological findings or clinical courses (malignant 26/benign 37). Semiconductor PET showed sensitivity of 92.3 % (24/26), specificity of 51.4 % (19/37), and accuracy of 68.2 % (43/63), while LSO-PET showed sensitivity of 84.6 % (22/26), specificity of 16.2 %(6/37), and accuracy of 44.4 % (28/63), respectively. Especially, semiconductor PET accurately diagnosed as true negative in the 13 of 14 lesions only detected by LSO-PET. ROC analyses revealed the diagnostic superiority of semiconductor PET from location of- and area under curve particularly in the study of small (≤10 mm) lesions.A new novel semiconductor PET scanner can increase diagnostic accuracy with reduction in false positive findings in the HNC patients mainly due to higher spatial resolution and lower noise than the LSO-PET. This new technology can lead to more accurate diagnosis and the more optimal therapeutic tactics in head and neck surgery.

Keywords: Semiconductor scanner; PET; Head and neck cancer

Three-dimensional brain phantom containing bone and grey matter structures with a realistic head contour by Hidehiro Iida; Yuki Hori; Kenji Ishida; Etsuko Imabayashi; Hiroshi Matsuda; Masaaki Takahashi; Hirotaka Maruno; Akihide Yamamoto; Kazuhiro Koshino; Junichiro Enmi; Satoshi Iguchi; Tetsuaki Moriguchi; Hidekazu Kawashima; Tsutomu Zeniya (pp. 25-36).

A physical 3-dimensional phantom that simulates PET/SPECT images of static regional cerebral blood flow in grey matter with a realistic head contour has been developed. This study examined the feasibility of using this phantom for evaluating PET/SPECT images.The phantom was constructed using a transparent, hydrophobic photo-curable polymer with a laser-modelling technique. The phantom was designed to contain the grey matter, the skull, and the trachea spaces filled with a radioactive solution, a bone-equivalent solution of K₂HPO₄, and air, respectively. The grey matter and bone compartments were designed to establish the connectivity. A series of experiments was performed to confirm the accuracy and reproducibility of the phantom using X-ray CT, SPECT, and PET.The total weight was 1997 ± 2 g excluding the inner liquid, and volumes were 563 ± 1 and 306 ± 2 mL, corresponding to the grey matter and bone compartments, respectively. The apparent attenuation coefficient averaged over the whole brain was 0.168 ± 0.006 cm⁻¹ for Tc-99 m, which was consistent with the previously reported value for humans (0.168 ± 0.010 cm⁻¹). Air bubbles were well removed from both grey-matter and bone compartments, as confirmed by X-ray CT. The phantom was well adapted to experiments using PET and SPECT devices.The 3-dimensional brain phantom constructed in this study may be of use for evaluating the adequacy of SPECT/PET reconstruction software programs.

Keywords: Brain phantom quality control; SPECT; PET; Attenuation correction

Early response of patients undergoing concurrent chemoradiotherapy for cervical cancer: a comparison of PET/CT and MRI by Jeong Eun Lee; Seung Jae Huh; Heerim Nam; Sang Gyu Ju (pp. 37-45).

To investigate the efficacy of positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) for early response evaluation of cervical cancer patients undergoing concurrent chemoradiotherapy (CCRT).Fifty-two patients were prospectively enrolled in the study. The pathologic findings were squamous cell carcinoma in 47 patients and adenocarcinoma in 5 patients. All patients underwent PET/CT and MRI scans before, during and within 1 month after completion of CCRT. The percent change in tumor volume during and after CCRT based on PET/CT and MRI images was compared.There were significant differences (p < 0.001) between the initial tumor volume and tumor volume during and after CCRT as measured by both PET/CT and MRI. During CCRT, the percent volume reduction based on PET/CT images was significantly greater than the percent volume reduction calculated from MRI images (p = 0.024). However, after the completion of CCRT, no significant differences were found in volume reduction as calculated based on PET/CT versus MRI images (p = 0.289). The percent volume reduction of adenocarcinomas was significantly smaller than that of squamous cell carcinomas based on both PET/CT (p = 0.041) and MRI images (p < 0.001).Significant decreases in tumor volume were observed during and after CCRT in patients with cervical cancer. Tumor volume reduction on PET/CT images was greater than that on MRI images during CCRT. We suggest that early PET/CT as well as MRI scans could be taken during CCRT to evaluate tumor response and allow personalized treatment of cervical cancer.

Keywords: Cervical cancer; PET/CT; MRI; CCRT; Treatment response

The current status of an FDG-PET cancer screening program in Japan, based on a 4-year (2006–2009) nationwide survey by Ryogo Minamimoto; Michio Senda; Seishi Jinnouchi; Takashi Terauchi; Tsuyoshi Yoshida; Takeshi Murano; Hiroshi Fukuda; Takeshi Iinuma; Kimiichi Uno; Sadahiko Nishizawa; Eriko Tsukamoto; Hiroshi Iwata; Takeshi Inoue; Kazuhiro Oguchi; Rumi Nakashima; Tomio Inoue (pp. 46-57).

The aim of this study was to survey the 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening program conducted in Japan.The “FDG-PET cancer screening program” included both FDG-PET and positron emission tomography with computed tomography (PET/CT) with or without other combined screening tests that were performed for cancer screening in asymptomatic subjects. A total of 155,456 subjects who underwent the FDG-PET cancer screening program during 2006–2009 were analyzed.Of the 155,456 subjects, positive findings suggesting possible cancer were noted in 16,955 (10.9 %). The number of cases with detected cancer was 1,912 (1.23 % of the total screened cases, annual range 1.14–1.30 %). Of the 1,912 cases of detected cancer, positive findings on FDG-PET were present in 1,491 cases (0.96 % of the total number of screened cases). According to the results of further examinations, the true positive rate for subjects with suggested possible cancer (positive predictive value) was 32.3 % with FDG-PET. Cancers of the colon/rectum, thyroid, lung, and breast were most frequently found (396, 353, 319, and 163 cases, respectively) with high PET sensitivity (85.9, 90.7, 86.8, 84.0 %, respectively). Prostate cancer and gastric cancer (165 and 124 cases, respectively) had low PET sensitivity (37.0 and 37.9 %, respectively). The Union for International Cancer Control (UICC) clinical stage of cancer found with the FDG-PET cancer screening program was mainly Stage I.The FDG-PET screening program in Japan has detected a variety of cancers at an early stage. However, several cancers were found in repeated FDG-PET cancer screening program, indicating the limitation of a one-time FDG-PET cancer screening program. The value of the FDG-PET cancer screening program is left to the judgment of individuals with regard to its potentials and limitations.

Keywords: FDG; PET; PET/CT; Cancer screening

Comparison of FDG-PET, MRI and CT for post radiofrequency ablation evaluation of hepatic tumors by Wengen Chen; Hongming Zhuang; Gang Cheng; Drew A. Torigian; Abass Alavi (pp. 58-64).

Treatment effect of radiofrequency ablation (RFA) is traditionally accomplished with MRI and/or CT. The aim of the study was to assess the role of FDG-PET in post RFA hepatic tumor evaluation, in comparison with MRI and CT.28 patients (33 hepatic RFA lesions) who had post RFA FDG-PET within 8 weeks of abdominopelvic MRI or CT were retrospectively reviewed. Accuracy of FDG-PET on post hepatic RFA evaluation was compared with MRI and/or CT based on clinical and imaging follow-up.Among total of 33 RFA-treated lesions, 17 had residual or recurrent tumor (positive). PET identified 16 with a sensitivity of 94.1 %. Of these 17 lesions, 12 had concurrent MRI and 8 were positive with a sensitivity of 66.7 %. Similarly, 6 out of the 17 lesions had CT and 4 were positive with a sensitivity of 66.7 %. Sixteen lesions were successfully ablated (negative). Among them FDG-PET was negative in 13 with a specificity of 81.3 %; MRI was performed in 8 and 7 were negative with a specificity of 87.5 %; CT was performed in 8 and 5 were negative with a specificity of 62.5 %. The overall accuracy of PET, MRI and CT was 87.9, 75.0, and 64.3 %, respectively. The average scan numbers for PET, MRI and CT to achieve a final accurate diagnosis were 1.121, 1.316 and 1.250, with a corresponding cost of $1455.2, $1845.8, and $933.8, respectively.The study suggests that FDG-PET is superior to MRI and/or CT and is more cost-effective in post RFA hepatic tumor assessment.

Keywords: FDG-PET; CT; MRI; Radiofrequency ablation; Hepatic tumor

Dynamic sequence respiratory gated perfusion pulmonary SPECT without external tracking device by Kenta Sakaguchi; Makoto Hosono; Masakazu Otsuka; Kohei Hanaoka; Kimio Usami; Tatsuro Uto; Kazunari Ishii (pp. 65-73).

The purpose of this study was to develop and evaluate a new method for respiratory gated pulmonary perfusion SPECT (RGPS) based on dynamic acquisition without using an external tracking device (ETD) or list-mode data acquisition.In the phantom study, our method used a dynamic sequence technique, which was specified by sequences of 50-ms acquisition during 30 s per view of SPECT instead of using an ETD. For this purpose, we created a computer program that identified respiratory phases by calculating the center of activity (COA) in each dynamic frame image. We compared RGPS using the dynamic sequence acquisition (RGPS-DS) and RGPS using ETD (RGPS-ETD) in phantom studies employing a cylinder phantom filled with technetium-99m solution attached to an instrument providing a simple harmonic motion. In the patient study, RGPS-DS was applied to data collected from 3 patients during a routine study of Tc-MAA pulmonary perfusion SPECT.In the phantom study, the calculation of COA indicated a good agreement between RGPS-DS and RGPS-ETD. With an oscillatory phantom movement amplitude of 30 mm, the amplitudes determined by RGPS-DS and RGPS-ETD (28.36 and 27.58 mm, respectively) were identical on considering a pixel size of 4.66 mm for reconstructed SPECT images. In the patient study, applicability of our method to patient data was demonstrated.We have showed the feasibility of our method to obtain RGPS without ETD, and conclude that RGPS-DS may be an innovative and efficient technique in respiratory gated pulmonary perfusion SPECT. Further studies with a larger number of patients should demonstrate the accuracy of our method.

Keywords: Respiration tracking device; SPECT; Lung; Dynamic acquisition

Significant impact of transient deterioration of renal function on dosimetry in PRRT by Sofie Van Binnebeek; Kristof Baete; Christelle Terwinghe; Bert Vanbilloen; Karin Haustermans; Luc Mortelmans; Ivan Borbath; Eric Van Cutsem; Chris Verslype; Felix M. Mottaghy; Alfons Verbruggen; Christophe M. Deroose (pp. 74-77).

Peptide receptor radionuclide therapy (PRRT), with ⁹⁰Y-DOTATOC and ¹⁷⁷Lu-DOTATATE as most clinically used radiopeptides, is widely used in the management of metastatic neuroendocrine tumors. With respect to radiation dosimetry, the kidneys are the critical organ for ⁹⁰Y-DOTATOC. Renal irradiation is significant because of reabsorption of the radiopeptide from the proximal tubuli and the resulting retention in the interstitium, mainly in the inner cortical zone. The high energy and consequently wide range in tissue of the yttrium-90 beta particle result in high absorbed doses to the kidney cortex and medulla. Accurate renal dosimetry can help minimizing radiation nephropathy. We report a case of a 69-year-old candidate for PRRT with an acceptable kidney function at the time of screening. When performing ¹¹¹In-octreotide pretreatment dosimetry 3 weeks later, we observed a drastic deterioration in kidney function, caused by undisclosed non-steroidal anti-inflammatory drug intake. The calculated kidney biological effective dose (BED) was 153 Gy after four projected cycles. PRRT was canceled as our full-course BED limit is 37 Gy and the patient was switched to morphine analgesics. Renal function normalized after 3 months and repeated dosimetry yielded an acceptable kidney BED of 28 Gy after four projected cycles (7 Gy/cycle). This case emphasizes that acute kidney insufficiency can yield toxic kidney doses in a single therapy cycle, with an inherent risk of persistent renal insufficiency. All clinical factors which might influence kidney function should be verified at screening and before PRRT administration.

Keywords: Dosimetry; Peptide receptor radionuclide therapy; Yttrium-90; Kidney function

Role of ¹⁸F-fluoride PET/CT in the assessment of multiple myeloma: initial experience by Yuji Nishiyama; Ukihide Tateishi; Kazuya Shizukuishi; Ayako Shishikura; Etsuko Yamazaki; Hiroto Shibata; Tomohiro Yoneyama; Yoshiaki Ishigatsubo; Tomio Inoue (pp. 78-83).

The aim of this study was to report our early experience with ¹⁸F-fluoride PET/CT for detecting lesions and evaluate the usefulness of this modality in the assessment of multiple myeloma (MM). ¹⁸F-fluoride PET/CT and ^99mTc-MDP bone scintigraphy (BS) studies from 7 myeloma patients (4 male and 3 female, mean age 55 years) diagnosed according to standard criteria were reviewed retrospectively. Two reviewers visually and quantitatively analyzed the images and recorded their findings after reaching a consensus. Diagnostic certainty regarding the presence or absence of myeloma lesions was evaluated according to the reference standard consisting of whole-body magnetic resonance imaging and whole-body X-ray.A total of 93 affected areas were definite according to the reference standard. Of these, 83 affected areas (89 %) were identified on ¹⁸F-fluoride PET/CT, whereas 54 affected areas (58 %) were found on BS. Mean SUVmax in the affected areas was 9.8 ± 3.2 (standard deviation) ranging from 5.0 to 21.2. A total of s17 lesions with bone fracture were also detected by ¹⁸F-fluoride PET/CT and 2 lesions (12 %) were negative on BS.Our result showed that ¹⁸F-fluoride PET was a possible modality to detect areas of lesions in patients with MM.

Keywords: Multiple myeloma; ¹⁸F-fluoride; NaF; PET; PET/CT; Bone imaging

A heuristic statistical stopping rule for iterative reconstruction in emission tomography by F. Ben Bouallègue; J. F. Crouzet; D. Mariano-Goulart (pp. 84-95).

We propose a statistical stopping criterion for iterative reconstruction in emission tomography based on a heuristic statistical description of the reconstruction process.The method was assessed for MLEM reconstruction. Based on Monte-Carlo numerical simulations and using a perfectly modeled system matrix, our method was compared with classical iterative reconstruction followed by low-pass filtering in terms of Euclidian distance to the exact object, noise, and resolution. The stopping criterion was then evaluated with realistic PET data of a Hoffman brain phantom produced using the GATE platform for different count levels.The numerical experiments showed that compared with the classical method, our technique yielded significant improvement of the noise-resolution tradeoff for a wide range of counting statistics compatible with routine clinical settings. When working with realistic data, the stopping rule allowed a qualitatively and quantitatively efficient determination of the optimal image.Our method appears to give a reliable estimation of the optimal stopping point for iterative reconstruction. It should thus be of practical interest as it produces images with similar or better quality than classical post-filtered iterative reconstruction with a mastered computation time.

Keywords: Emission tomography; Iterative reconstruction; MLEM; Stopping criterion

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Annals of Nuclear Medicine (v.27, #1)