Check out our New Publishers' Select for Free Articles

Annals of Nuclear Medicine (v.26, #1)

Advances in PET myocardial perfusion imaging: F-18 labeled tracers by Christoph Rischpler; Min-Jae Park; George S. K. Fung; Mehrbod Javadi; Benjamin M. W. Tsui; Takahiro Higuchi (pp. 1-6).

Coronary artery disease and its related cardiac disorders represent the most common cause of death in the USA and Western world. Despite advancements in treatment and accompanying improvements in outcome with current diagnostic and therapeutic modalities, it is the correct assignment of these diagnostic techniques and treatment options which are crucial. From a diagnostic standpoint, SPECT myocardial perfusion imaging (MPI) using traditional radiotracers like thallium-201 chloride, Tc-99m sestamibi or Tc-99m tetrofosmin is the most utilized imaging technique. However, PET MPI using N-13 ammonia, rubidium-82 chloride or O-15 water is increasing in availability and usage as a result of the growing number of medical centers with new-generation PET/CT systems taking advantage of the superior imaging properties of PET over SPECT. The routine clinical use of PET MPI is still limited, in part because of the short half-life of conventional PET MPI tracers. The disadvantages of these conventional PET tracers include expensive onsite production and inconvenient on-scanner tracer administration making them unsuitable for physical exercise stress imaging. Recently, two F-18 labeled radiotracers with longer radioactive half-lives than conventional PET imaging agents have been introduced. These are flurpiridaz F 18 (formerly known as F-18 BMS747158-02) and F-18 fluorobenzyltriphenylphosphonium. These longer half-life F-18 labeled perfusion tracers can overcome the production and protocol limitations of currently used radiotracers for PET MPI.

Keywords: Myocardial perfusion; PET; Ischemic heart disease; Flurpiridaz; FBnTP

Correction of head movements in positron emission tomography using point source tracking system: a simulation study by Babak Nazarparvar; Mojtaba Shamsaei; Hossein Rajabi (pp. 7-15).

The motion of the head during brain positron emission tomography (PET) acquisitions has been identified as a source of artifact in the reconstructed image. In this study, a method is described to develop an image-based motion correction technique for correcting the post-acquisition data without using external optical motion-tracking system such as POLARIS.In this technique, GATE has been used to simulate PET brain scan using point sources mounted around the head to accurately monitor the position of the head during the time frames.The measurement of head motion in each frame showed a transformation in the image frame matrix, resulting in a fully corrected data set.Using different kinds of phantoms and motions, the accuracy of the correction method is tested and its applicability to experimental studies is demonstrated as well.

Keywords: Motion correction; Point sources; PET; MAF (multiple acquisition frame); GATE

Evaluation of a novel normal database with matched SPECT systems and optimal pre-filter parameters for 3D-SSP by Hideo Onishi; Norikazu Matsutomo; Yuji Kai; Yoshiharu Kangai; Hizuru Amijima; Takeshi Yamaguchi (pp. 16-25).

A normal perfusion database (NDB) is imperative for the statistical imaging of brain function. This study validates a novel NDB created under the same injection dose and acquisition conditions for three gamma camera systems and evaluates optimal pre-filter parameters for three-dimensional stereotactic surface projections (3D-SSPs).We compared a novel NDB that matched the databases in each of three vendor gamma camera systems with a conventionally constructed NDB (conventional NDB) and a NDB constructed in-house for 3D-SSP. We generated hypoperfused regions where pre-specified volumes were simulated for various areas in SPECT images. The properties of each NDB were evaluated based on the distribution of the standard deviation (SD). Abnormal accumulation regions were validated using Z, extent, and artifactual scores. Detection error was used to evaluate the optimal Butterworth pre-filter cutoff frequency with the perfusion defect rate (PDR) in 3D-SSP.The SD distribution was the same in the novel NDB and in the NDB constructed in-house, and the SD of the peak distribution was 0.08–0.07. The Z and extent scores of the novel DB and the NDB constructed in-house were similar, but increased along with the artifactual scores when using the conventional NDB. Many artifacts appeared in the Z score map when using the conventional NDB. The detection error deviated from the actual value by −1.3% at a cutoff frequency of 0.58 cycles/cm and a PDR of 30%, which was the lowest. The cutoff frequency became lower or higher, and the low-perfusion defect rate increased according to the increasing detection error. The optimal cutoff frequency was between 0.52 and 0.58 cycles/cm.We generated a novel NDB according to the individual devices and compared it with a conventional and a NDB constructed in-house. The Z and extent scores were essentially equal when using the novel DB and the NDB constructed in-house, but considerably differed when using the conventional NDB. The optimal cutoff frequency of the Butterworth filter evaluated from the detection error was in the range of 0.52–0.58 cycles/cm. The detection error increased the perfusion defect rate by <15% and this was undetectable in 3D-SSP. The next step will be to improve the accuracy of the extent of abnormal regions and the sensitivity of the Z score using a novel NDB constructed according to the individual devices.

Keywords: SPECT; Brain perfusion; Three-dimensional stereotactic surface projections; Alzheimer’s disease; Normal database

Diagnostic accuracy of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography in differentiated thyroid cancer patients with elevated thyroglobulin and negative ¹³¹I whole body scan: evaluation by thyroglobulin level by Sae Jung Na; Ie Ryung Yoo; Joo Hyun O; Chenghe Lin; Qiuyu Lin; Sung Hoon Kim; Soo Kyo Chung (pp. 26-34).

To evaluate the diagnostic accuracy of ¹⁸F-FDG PET/CT in detection of recurrent differentiated thyroid cancer (DTC) in patients with elevated stimulated thyroglobulin (Tg) or anti-Tg antibody (Ab) levels, and negative ¹³¹I whole body scan according to the Tg level.PET/CT images of well DTC patients who had total thyroidectomy and radioiodine ablation were included. Patients showing elevated Tg titer (≥2.0 ng/ml after TSH stimulation) or elevated anti-Tg titer (≥70.0 IU/ml) while diagnostic radioiodine scan was negative were enrolled. PET/CT was classified as positive or negative on the basis of visual interpretation. The maximum standard uptake values (SUVmax) of the suspected lesions on PET/CT were also recorded. The PET/CT findings were compared with histological or clinical follow-up results based on other imaging modalities and serum Tg/anti-Tg Ab titers. The diagnostic performance of PET/CT was compared among 4 subgroups according to the Tg level [2 ng/ml ≤ stimulated Tg (sTg) < 5 ng/ml, 5 ng/ml ≤ sTg < 10 ng/ml, 10 ng/ml ≤ sTg < 20 ng/ml, and ≥20 ng/ml].A total of 68 PET/CT images from 60 patients were included, and histological confirmations were available in 32 images. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of PET/CT were 69.4, 66.7, 69.1, 95.6, and 17.4%, respectively. There were 3 PET/CT cases with high anti-Tg Ab level, and low (<2 ng/ml) Tg level, and all 3 were positive of recurrence. The mean SUVmax of the suspected lesions on PET/CT was 2.9 ± 4.5 (range 1.3–29.7). The sensitivity of PET/CT according to Tg levels was 28.6% when Tg was between 2 and 5, 57.1% between 5 and 10, 60.0% between 10 and 20, and 85.7% when Tg was equal to or greater than 20 ng/ml sub-groups, respectively.Diagnostic accuracy of FDG PET in radioiodine negative thyroid cancer may vary depending on serum Tg levels at imaging. ¹⁸F-FDG PET/CT is useful in detection and localization of recurrent thyroid cancer in patients with negative diagnostic radioiodine scan despite elevated Tg greater than 20 ng/ml or high anti-Tg Ab titers. In contrast, PET/CT provides little additional information when the Tg is less than 5 ng/ml.

Keywords: Thyroid cancer; ¹⁸F-FDG; PET/CT; Thyroglobulin; Radioiodine imaging

Cortical-limbic regions modulate depression and anxiety factors in functional dyspepsia: a PET-CT study by Mai-lan Liu; Fan-rong Liang; Fang Zeng; Yong Tang; Lei Lan; Wen-zhong Song (pp. 35-40).

To observe some specific brain areas or cerebral functional network participating in the modulation of depression and anxiety factors in functional dyspepsia (FD) patients by detecting cerebral glucose metabolism (CGM) in fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET-CT) scans.Eight FD patients with depression and anxiety (DA-FD group) and eight FD patients without depression and anxiety (non-DA-FD group) were recruited and evaluated by the Nepean Dyspepsia Index (NDI) and Dyspepsia Symptom Scores (DSS). Cerebral ¹⁸F-FDG PET-CT scans were performed on the DA-FD group and non-DA-FD group, respectively. The differences in CGM between the two groups were analyzed with SPM2.Extensive changes in the CGM signals were observed in the cerebral cortex and limbic system of FD patients with depression and anxiety. Compared to non-DA-FD patients, DA-FD patients showed a higher glucose metabolism in the right postcentral gyrus (BA 1 and 5), inferior frontal gyrus (BA 45), superior temporal gyrus (BA 22), middle temporal gyrus (BA 22), inferior parietal lobule (BA 40), lingual gyrus (BA 18) and the left middle occipital gyrus (BA 37), as well as the limbic system including the left thalamus, lateral globus pallidus, parahippocampal gyrus (BA 35), right insular cortex (BA 13) and parahippocampal gyrus (BA 18); a lower glucose metabolism was presented in the left middle cingulated gyrus (BA 24), the right superior frontal gyrus (BA 6), the medial frontal gyrus (BA 6) and middle temporal gyrus (BA 21).An extensive cortical-limbic brain network might modulate the procession of FD patients with depression and anxiety factors.

Keywords: FD; Depression and anxiety; Cerebral glucose metabolism; PET-CT

Micronucleus evaluation for determining the chromosomal breakages after radionuclide synovectomy in patients with hemophilia by Kaan Kavakli; Ozgur Cogulu; Emin Karaca; Burak Durmaz; Ferda Ozkinay; Semih Aydogdu; Hayal Ozkilic; Can Balkan; Deniz Karapinar; Yılmaz Ay (pp. 41-46).

To investigate the genotoxic effects of ⁹⁰Y and ¹⁸⁶Re in patients with hemophilia who were undergoing radionuclide synovectomy (RS) procedure in the last 3 years.Nineteen patients were enrolled in the study. Most of the patients (n = 17) were hemophilia-A (mean age 20.6 ± 10.5 years) and 18 patients (mean age 22.6 ± 10.6 years) with hemophilia who were not exposed to RS procedure were included in the study as control group. Most cases in the control group (n = 13) were hemophilia-A. ⁹⁰Y for knee joints and ¹⁸⁶Re for elbow or ankle joints were used to perform RS in hemophilic patients. We studied the micronucleus (MN) test on peripheral blood lymphocytes as an indicator of radiation-induced cytogenetic damage and calculated nuclear division index.There was no significant difference between the patients with and without RS with respect to MN values. However, both values obtained in RS-exposed patients and control group were much elevated than values reported in literature from healthy controls. The mean MN values of patients below 20 years old were much lower but not significant than those above 20 years old. MN frequencies between ¹⁸⁶Re and ⁹⁰Y groups were also analyzed, and no significant difference was observed. Hemophilia patients who were treated with ¹⁸⁶Re showed higher levels of MN compared to patients treated with ⁹⁰Y although the difference was not significant.Radioisotope synovectomy (RS) seems to be a safe procedure not causing a significant genotoxic effect on hemophilic patients, however, further studies including larger series of patients are needed to better understand the effects of RS on patients’ health.

Keywords: Hemophilia; Radioisotope synovectomy; ⁹⁰Y (yttrium 90); ¹⁸⁶Re (rhenium 186); Chromosomal breakages

Hemodynamic improvement of anterior cerebral artery territory perfusion induced by bifrontal encephalo(periosteal)synangiosis in pediatric patients with moyamoya disease: a study with brain perfusion SPECT by Yoo Sung Song; So Won Oh; Yu Keong Kim; Seung-Ki Kim; Kyu-Chang Wang; Dong Soo Lee (pp. 47-57).

The reinforcement of the anterior cerebral artery (ACA) territory perfusion is important for the future intellectual functioning of pediatric moyamoya disease (MMD) patients. To evaluate the hemodynamic improvement of the ACA territory, bifrontal encephalogaleo-(periosteal)synangiosis [EG(P)S] combined with encephaloduroarteriosynangiosis (EDAS) was compared with EDAS alone in pediatric MMD patients using brain perfusion SPECT.Among 36 patients (M:F = 16:20; mean age, 9.5 ± 3.0 years) who were surgically treated for MMD, EDAS was performed in 17 patients, and EDAS with bifrontal EG(P)S in 19 patients. Hemodynamic parameters consisting of basal cerebral perfusion, acetazolamide-challenge stress perfusion, and cerebrovascular reserve index were estimated using brain perfusion SPECT and probabilistic perfusion maps for the ACA and middle cerebral artery (MCA) territories. Cerebral angiography was performed to confirm revascularization.Both the EDAS only (p = 0.04) and EDAS with EG(P)S group (p < 0.001) had significant improvements in cerebrovascular reserve of the ipsilateral MCA territory. The EDAS with EG(P)S group had significant improvements, not only in basal perfusion of the ipsilateral ACA territory (p = 0.03) but also in the cerebrovascular reserve of the bilateral ACA territories (p < 0.01). In parallel with the hemodynamic changes assessed by brain perfusion SPECT, neovascularization was noted in the ipsilateral MCA territory in both the EDAS only and EDAS with EG(P)S group, and in the ipsilateral ACA territory in the EDAS with EG(P)S group on the postoperative cerebral angiography.EDAS with bifrontal EG(P)S induces significant improvements in the ACA and MCA territories, while EDAS generates significant improvements in the MCA territory only.

Keywords: Moyamoya disease; EDAS; EG(P)S; Brain perfusion SPECT; Probabilistic perfusion map

Pediatric lymphoma: metabolic tumor burden as a quantitative index for treatment response evaluation by Punit Sharma; Arun Gupta; Chetan Patel; Sameer Bakhshi; Arun Malhotra; Rakesh Kumar (pp. 58-66).

Metabolic tumor burden (MTB) incorporates the advantages of the existing indices: the metabolic volume of the lesion calculated by size-dependent thresholding on positron emission tomography–computed tomography (PET–CT) along with its aggressiveness as determined by standardized uptake value (SUV). This study was conducted to investigate whether MTB can be used as an objective index for monitoring therapy response in pediatric lymphoma.Forty-two pediatric patients (35 male and 7 female) with histologically proven lymphomas (26 Hodgkin’s and 16 non-Hodgkin’s) were evaluated. MTB was assessed in baseline, early interim (after 2 cycles) and post-therapy PET–CT studies using RT_Image software. Size-dependent thresholding based on a phantom study conducted at our institute was used for the calculation of metabolic tumor volume (MTV). MTB was given as the product of MTV and the SUVmean. Summation of MTB from all lesions gave the whole body MTB. Baseline, early interim and post-therapy SUVmax and whole body MTB of the partial and complete response group were compared.Of 42 patients, 37 had complete response and 5 had partial response at the end of therapy based on clinical, CECT and bone marrow biopsy findings. SUVmax showed an overall reduction of 87.4% while MTB showed a reduction of 96.4% between baseline and early interim PET–CT scan. Similarly, SUVmax showed an overall reduction of 95.2% while MTB showed a reduction of 99.6% between baseline and post-therapy scan. There was significant difference between MTB of partial response and complete response group at baseline and early interim PET–CT (p 0.031 and 0.012, respectively). No such significant difference was found for SUVmax.Whole body MTB appears to be useful quantitative parameter for the assessment of treatment response using PET–CT in pediatric lymphoma patients.

Keywords: Pediatric lymphoma; PET–CT; Metabolic tumor burden (MTB); Treatment response

High resolution SPECT imaging for visualization of intratumoral heterogeneity using a SPECT/CT scanner dedicated for small animal imaging by Izumi O. Umeda; Kotaro Tani; Keisuke Tsuda; Masamitsu Kobayashi; Mayumi Ogata; Sadaaki Kimura; Mitsuyoshi Yoshimoto; Shuji Kojima; Kunikazu Moribe; Keiji Yamamoto; Noriyuki Moriyama; Hirofumi Fujii (pp. 67-76).

Tumor interiors are never homogeneous and in vivo visualization of intratumoral heterogeneity would be an innovation that contributes to improved cancer therapy. But, conventional nuclear medicine tests have failed to visualize heterogeneity in vivo because of limited spatial resolution. Recently developed single photon emission computed tomographic (SPECT) scanners dedicated for small animal imaging are of interest due to their excellent spatial resolution of <1 mm, but few studies have focused on the evaluation of intratumoral heterogeneity. We investigated the optimal conditions related to high resolution imaging of heterogeneous tumor interiors using a small animal SPECT scanner.The conditions related to SPECT/CT visualization of heterogeneous tumor interiors were investigated using phantoms with ¹¹¹In and simulations of actual small animal imaging. The optimal conditions obtained were validated by in vivo imaging of sarcoma 180-bearing mice.Larger number of counts must be obtained within limited acquisition time to visualize tumor heterogeneity in vivo in animal imaging, compared to cases that simply detect tumors. At an acquisition time of 30 min, better image quality was obtained with pinhole apertures diameter of 1.4 mm than of 1.0 mm. The obtained best spatial resolution was 1.3 mm, it was acceptable for our purpose, though a little worse than the best possible performance of the scanner (1.0 mm). Additionally, the reconstruction parameters, such as noise suppression, voxel size, and iteration/subset number, needed to be optimized under the limited conditions and were different from those found under the ideal condition. The minimal radioactivity concentration for visualization of heterogeneous tumor interiors was estimated to be as high as 0.2–0.5 MBq/mL. Liposomes containing ¹¹¹In met this requirement and were administered to tumor-bearing mice. SPECT imaging successfully showed heterogeneous ¹¹¹In distribution within the tumors in vivo with good spatial resolution. A threshold of 0.2 MBq/g for clear visualization of tumor heterogeneity was validated. Autoradiograms obtained ex vivo of excised tumors confirmed that the in vivo SPECT images accurately depicted the heterogeneous intratumoral accumulation of liposomes.Intratumoral heterogeneity was successfully visualized under the optimized conditions using a SPECT/CT scanner.

Keywords: Small animal; SPECT; Tumor heterogeneity; ¹¹¹In; Liposome

Can ¹⁸F-FDG-PET/CT be generally recommended in patients with differentiated thyroid carcinoma and elevated thyroglobulin levels but negative I-131 whole body scan? by Peter Bannas; Thorsten Derlin; Michael Groth; Ivayla Apostolova; Gerhard Adam; Janos Mester; Susanne Klutmann (pp. 77-85).

Exact localization of recurrent iodine-negative thyroid cancer is mandatory, since surgery is the only curative therapy option in patients with iodine-negative tumor tissue. The aim of this study was to evaluate the impact of ¹⁸F-FDG-PET/CT as a routine diagnostic tool on clinical management in patients with suspected thyroid cancer recurrence and elevated serum thyroglobulin (Tg) but negative radioiodine whole body scan.After total thyroidectomy followed by radioiodine ablation, 30 consecutive patients with differentiated thyroid cancer, elevated serum thyroglobulin levels and negative whole body radioiodine scan underwent ¹⁸F-FDG-PET/CT. Results were verified by histology, ultrasound, or clinical follow-up. Diagnostic accuracy was determined for the whole study population and for subgroups with serum thyroglobulin below and above 10 ng/ml, respectively. Impact of PET/CT on clinical management was assessed.PET/CT identified FDG accumulating lesions in 19 of 30 patients. 17 were true-positive and 2 false-positive. In the true-positive group, 11 of the 17 patients had loco-regional disease, 3 had distant metastases only and 3 patients had both loco-regional and distant metastatic involvement. ¹⁸F-FDG-PET/CT was true-negative in 3 patients and false-negative in 8 patients. Overall sensitivity, specificity and accuracy were 68.0, 60.0, and 66.7%, respectively. In the subgroup of patients with serum thyroglobulin above 10 ng/ml (n = 21) the sensitivity, specificity and accuracy were substantially higher with 70.0, 100.0, and 71.4%, respectively. Clinical management was changed for 17 (57%) of 30 patients, guiding to a curative surgical intervention in 9 patients (30%). ¹⁸F-FDG-PET/CT enables detection and precise localization of loco-regional recurrence and distant metastases of differentiated thyroid cancer in patients with elevated serum thyroglobulin but negative radioiodine with significant impact on patient management and can therefore be recommended as a routine diagnostic tool.

Keywords: Thyroid cancer; Negative radioiodine whole body scan; ¹⁸F-FDG-PET/CT; PET/CT; Differentiated thyroid carcinoma; Thyroglobulin

FDG-avid sclerotic bone metastases in breast cancer patients: a PET/CT case series by Bas B. Koolen; Erik Vegt; Emiel J. Th. Rutgers; Wouter V. Vogel; Marcel P. M. Stokkel; Cornelis A. Hoefnagel; Annemarie Fioole-Bruining; Marie-Jeanne T. F. D. Vrancken Peeters; Renato A. Valdés Olmos (pp. 86-91).

Distant metastases from breast cancer most frequently occur in the skeleton. Although 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), with or without computed tomography (CT), is superior to bone scintigraphy for the detection of osteolytic bone metastases, it has been reported that sclerotic bone metastases frequently show no or only a low degree of FDG uptake on PET and PET/CT. Since both lytic and sclerotic metastases can occur in breast cancer patients, bone scintigraphy may remain of additional value in these patients. In this case series, we describe four breast cancer patients in whom FDG PET/CT has clearly visualized sclerotic bone metastases because of increased FDG uptake. Not so much the type of metastasis (sclerotic or lytic), but possibly the characteristics of the primary tumor or treatments prior to the FDG PET/CT scan might influence the degree of FDG uptake of bone metastases. The ability to detect sclerotic bone metastases based on increased FDG uptake supports the use of FDG PET/CT as a staging procedure in breast cancer patients, but knowledge of factors determining the visibility of bone metastases with FDG PET/CT is crucial.

Keywords: Breast cancer; Bone metastases; Sclerotic; PET/CT; FDG

Fast Monte Carlo-simulator with full collimator and detector response modelling for SPECT by Antti O. Sohlberg; Markus T. Kajaste (pp. 92-98).

Monte Carlo (MC)-simulations have proved to be a valuable tool in studying SPECT-reconstruction algorithms. Despite their popularity, the use of Monte Carlo-simulations is still often limited by their large computation demand. This is especially true in situations where full collimator and detector modelling with septal penetration, scatter and X-ray fluorescence needs to be included. This paper presents a rapid and simple MC-simulator, which can effectively reduce the computation times.The simulator was built on the convolution-based forced detection principle, which can markedly lower the number of simulated photons. Full collimator and detector response look-up tables are pre-simulated and then later used in the actual MC-simulations to model the system response. The developed simulator was validated by comparing it against ¹²³I point source measurements made with a clinical gamma camera system and against ^99mTc software phantom simulations made with the SIMIND MC-package.The results showed good agreement between the new simulator, measurements and the SIMIND-package. The new simulator provided near noise-free projection data in approximately 1.5 min per projection with ^99mTc, which was less than one-tenth of SIMIND’s time.The developed MC-simulator can markedly decrease the simulation time without sacrificing image quality.

Keywords: Monte Carlo-simulation; Collimator response; SPECT

Sections

Personal tools

Annals of Nuclear Medicine (v.26, #1)

Sections

Personal tools

Local resources

Annals of Nuclear Medicine (v.26, #1)