Determination of a reliable assessment for occupational eye lens dose in nuclear medicine

The most recent statement published by the International Commission on Radiological Protection describes a reduction in the maximum allowable occupational eye lens dose from 150 to 20 mSv/year (averaged over 5‐year periods). Exposing the eye lens to radiation is a concern for nuclear medicine staff who handle radionuclide tracers with various levels of photon energy. This study aimed to define the optimal dosimeter and means of measuring the amount of exposure to which the eye lens is exposed during a routine nuclear medicine practice. A RANDO human phantom attached to Glass Badge and Luminess Badge for body or neck, DOSIRIS and VISION for eyes, and nanoDot for body, neck, and eyes was exposed to ^99mTc, ¹²³I, and ¹⁸F radionuclides. Sealed syringe sources of each radionuclide were positioned 30 cm from the abdomen of the phantom. Estimated exposure based on measurement conditions (i.e., air kerma rate constants, conversion coefficient, distance, activity, and exposure time) was compared measured dose equivalent of each dosimeter. Differences in body, neck, and eye lens dosimeters were statistically analyzed. The 10‐mm dose equivalent significantly differed between the Glass Badge and Luminess Badge for the neck, but these were almost equivalent at the body. The 0.07‐mm dose equivalent for the nanoDot dosimeters was greatly overestimated compared to the estimated exposure of ^99mTc and ¹²³I radionuclides. Measured dose equivalents of exposure significantly differed between the body and eye lens dosimeters with respect to ¹⁸F. Although accurately measuring radiation exposure to the eye lenses of nuclear medicine staff is conventionally monitored using dosimeters worn on the chest or abdomen, eye lens dosimeters that provide a 3‐mm dose equivalent near the eye would be a more reliable means of assessing radiation doses in the mixed radiation environment of nuclear medicine.

Changing methods of education during a pandemic: questionnaire survey about examinations for nuclear medicine technology at educational institutions in Japan

Coronavirus disease 2019 (COVID-19) has spread around the world. Its effects go far beyond health care: education has to be conducted so as to prevent infection among students and faculty. Accordingly, changes have occurred in Japan’s educational institutions, including methods of preparing students for examinations for nuclear medicine. To assess the quality of training for radiologic technologists, we investigated the related changes undertaken at educational institutions. We investigated the lecture format for teaching nuclear medicine technology at Japanese institutions during COVID-19 and efforts to ensure the quality of conventional education. Methods: We sent a questionnaire to 19 Japanese institutions. It addressed the lecture format and initiatives in examinations for nuclear medicine technology in the first and second semesters of 2020. Results: We obtained responses from 17 institutions. In the first semester of 2020, the lecture format for nuclear medicine technology included remote, hybrid (combination of remote and face-to-face), and video-on-demand lectures. To reinforce the effect of the new teaching formats, institutions adopted various methods, such as enhancing the possibility of allowing students to ask questions, increasing the number of quizzes during lectures, delivering lectures to YouTube, and introducing an e-learning system. In the second semester of 2020, the lecture format included face-to-face, remote, hybrid, and video-on-demand lectures. In that second semester, the number of institutions providing face-to-face lectures while taking thorough measures against infection showed a marked increase. Conclusion: The institutions introduced various educational techniques and initiatives. They prioritized students’ understanding of lecture content and applied what they considered the best teaching methods. Sharing information about the changes adopted at different institutions should help promote good radiologic technologists—even during a pandemic.

[Validation of Simulation Codes for Nuclear Imaging Using Digital Phantoms]

Validation study of simulation codes was performed based on the measurement of a sphere phantom and the National Electrical Manufacturers Association (NEMA) body phantoms. SIMIND and Prominence Processor were used for the simulation. Both source and density maps were generated using the characteristics of ^99mTc energy. A full width at half maximum (FWHM) of the sphere phantom was measured and simulated. Simulated recovery coefficient and the background count coefficient of variation were also compared with the measured values in the body phantom study. When the two simulation codes were compared with actual measurements, maximum relative errors of FWHM values were 3.6% for Prominence Processor and -10.0% for SIMIND. The maximum relative errors of relative recovery coefficients exhibited 11.8% for Prominence Processor and -2.0% for SIMIND in the body phantom study. The coefficients of variation of the SPECT count in the background were significantly different among the measurement and two simulation codes. The simulated FWHM values and recovery coefficients paralleled measured results. However, the noise characteristic differed among actual measurements and two simulation codes in the background count statistics.

[Radiological Technology for Targeted Radionuclide Therapy]

Targeted radioisotope therapy (TRT) is a radiotherapy using radioisotope or drug incorporating it and has been used as a treatment for selectively irradiating cancer cells. In recent years, interest in TRT has increased due to improvements in radionuclide production technology, development of new drugs and imaging modalities, and improvements in radiation technology. In order to enhance the effect of TRT, measurement of individual radiation doses to tumor tissue and organs at risk is important using highly quantitative nuclear medicine images. In this paper, we present a review of literature on optimization of TRT, which is a new research area from the perspective of radiation technology.

[A Nationwide Survey on Additional Scan in Nuclear Medicine Imaging]

The aim of the present study was to clarify the routine protocols and the frequency of added or omitted imaging on nuclear medicine imaging in Japan. A nationwide survey on routine protocols and current state of added or omitted imaging in major nuclear medicine imaging were performed for Japanese nuclear medicine technologist. The survey showed that the routine protocols were almost 100% fixed, some of the routine protocols were found to be useful and percentage of imaging techniques such as single photon emission computed tomography/computed tomography that increased patient burden and reduced through put were low. Furthermore, the survey showed that additional or omission imaging were frequently performed on bone scintigraphy and positron emission tomography and added or omitted judgements were often depend upon the rule of thumb by nuclear medicine technologist. In this study, we have concluded that the quality of examination and the diagnosis might depend on the knowledge of nuclear medicine technologist, performed added or omitted imaging.

The 2020 national diagnostic reference levels for nuclear medicine in Japan

The diagnostic reference levels (DRLs) are one of several effective tools for optimizing nuclear medicine examinations and reducing patient exposure. With the advances in imaging technology and alterations of examination protocols, the DRLs must be reviewed periodically. The first DRLs in Japan were established in 2015, and since 5 years have passed, it is time to review and revise the DRLs. We conducted a survey to investigate the administered activities of radiopharmaceuticals and the radiation doses of computed tomography (CT) in hybrid CT accompanied by single photon emission computed tomography (SPECT)/CT and positron emission tomography (PET)/CT. We distributed a Web-based survey to 915 nuclear medicine facilities throughout Japan and survey responses were provided by 256 nuclear medicine facilities (response rate 28%). We asked for the facility's median actual administered activity and median radiation dose of hybrid CT when SPECT/CT or PET/CT was performed for patients with standard habitus in the standard protocol of the facility for each nuclear medicine examination. We determined the new DRLs based on the 75th percentile referring to the 2015 DRLs, drug package inserts, and updated guidelines. The 2020 DRLs are almost the same as the 2015 DRLs, but for the relatively long-lived radionuclides, the DRLs are set low due to the changes in the Japanese delivery system. There are no items set higher than the previous values. Although the DRLs determined this time are roughly equivalent to the DRLs used in the US, overall they tend to be higher than the European DRLs. The DRLs of the radiation dose of CT in hybrid CT vary widely depending on each imaging site and the purpose of the examination.

Imaging technology for myocardial perfusion single-photon emission computed tomography 2018 in Japan

AIM

Recently, nuclear cardiology has dramatically advanced by a new technology development such as the device, short-term acquisition system, image reconstruction algorithm and image analysis. Although these innovations have been gradually employed in routine examinations, we did not investigate the current use of image acquisition, image reconstruction, and image analysis with myocardial perfusion single-photon emission computed tomography (MPS). We investigated the current status of MPS imaging technology in Japan.

METHODS

We carried out a survey using a Web-based questionnaire system, the opening of which was announced via e-mail, and it was available on a website for 3 months. We collected data on the current use of MPS with ²⁰¹Tl and/or ^99mTc agents with respect to routine protocols, image acquisition, image reconstruction, and image analysis.

RESULTS

We received responses to the Web-based questionnaire from 178 and 174 people for ^99mTc and ²⁰¹Tl MPS, respectively. The routine protocols of MPS of stress-rest and rest-stress MPS on 1-day protocols with ^99mTc were 41.2% and 14.5%, respectively, and the rest-only scan response rate was 23.7%, whereas that of ²⁰¹Tl MPS was 65.9% with stress-rest MPS, 19.0% with rest-only MPS, and 10.9% with stress-rest MPS adding a rest scan 24 h after injection. The filtered back projection (FBP) method is most commonly used image reconstruction method, yielding 70.5% for ^99mTc MPS and 76.8% for ²⁰¹Tl MPS, including combined FBP and ordered subset expectation maximization method. The results for no-correction (NC) images were 49.2% with ^99mTc MPS and 55.2% with ²⁰¹Tl MPS including the response of NC and combined attenuation correction (AC) and scatter correction (SC) (i.e., ACSC) images. The AC or ACSC images of ^99mTc and ²⁰¹Tl were provided by 30-40% of the institutions surveyed.

CONCLUSIONS

We investigated the current status of MPS imaging technology in Japan, and found that although the use of various technical developments has been reported, some of these technologies have not been utilized effectively. Hence, we expect that nuclear medicine technology will be used more effectively to improve diagnosis.

[Global Trends Survey for Targeted Radionuclide Therapy]

Radionuclide therapy has been used to help manage a range of diseases and has a role of growing importance, with an increasing impact on clinical practice globally. A survey in the field of Radionuclide therapy was conducted by reviewing 4199 science abstracts of main conference (Japanese Society of Radiological Technology, Japanese Society of Nuclear Medicine, Japanese Society of Nuclear Medicine Technology, Society of Nuclear Medicine and Molecular Imaging, European Association of Nuclear Medicine) held in 2016. This survey consisted of research content, modality for evaluation, dosimetry, radionuclide, and researcher's country. There tend to be a lot of studies related to targeted radionuclide therapy more than Japan (4%) in the United States (11%) or Europe (13%). Radiopharmaceuticals still un-approving in Japan were used in some of these studies. And many studies on dosimetry using PET or SPECT imaging were confirmed in the United States (37%) or in Europe (25%) compared with in Japan (14%). This survey has clarified the current status of Japan and global trend in the field of radionuclide therapy.

GRP78 clustering at the cell surface of neurons transduces the action of exogenous alpha-synuclein

Mutation or multiplication of the alpha-synuclein (Syn)-encoding gene is frequent cause of early onset Parkinson's disease (PD). Recent evidences point to the pathogenic role of excess Syn also in sporadic PD. Syn is a cytosolic protein, which has been shown to be released from neurons. Here we provide evidence that extracellular Syn induces an increase in surface-exposed glucose-related protein of 78 kDa (GRP78), which becomes clustered in microdomains of the neuronal plasma membrane. Upon interacting with Syn, GRP78 activates a signaling cascade leading to cofilin 1 inactivation and stabilization of microfilaments, thus affecting morphology and dynamics of actin cytoskeleton in cultured neurons. Downregulation of GRP78 abolishes the activity of exogenous Syn, indicating that it is the primary target of Syn. Inactivation of cofilin 1 and stabilization of actin cytoskeleton are present also in fibroblasts derived from genetic PD patients, which show a dramatic increase in stress fibers. Similar changes are displayed by control cells incubated with the medium of PD fibroblasts, only when Syn is present. The accumulation of Syn in the extracellular milieu, its interaction with the plasma membrane and Syn-driven clustering of GRP78 appear, therefore, responsible for the dysregulation of actin turnover, leading to early deficits in synaptic function that precede neurodegeneration.

Expression of myeloperoxidase in acute myeloid leukemia blasts mirrors the distinct DNA methylation pattern involving the downregulation of DNA methyltransferase DNMT3B

Myeloperoxidase (MPO) has been associated with both a myeloid lineage commitment and favorable prognosis in patients with acute myeloid leukemia (AML). DNA methyltransferase inhibitors (decitabine and zeburaline) induced MPO gene promoter demethylation and MPO gene transcription in AML cells with low MPO activity. Therefore, MPO gene transcription was directly and indirectly regulated by DNA methylation. A DNA methylation microarray subsequently revealed a distinct methylation pattern in 33 genes, including DNA methyltransferase 3 beta (DNMT3B), in CD34-positive cells obtained from AML patients with a high percentage of MPO-positive blasts. Based on the inverse relationship between the methylation status of DNMT3B and MPO, we found an inverse relationship between DNMT3B and MPO transcription levels in CD34-positive AML cells (P=0.0283). In addition, a distinct methylation pattern was observed in five genes related to myeloid differentiation or therapeutic sensitivity in CD34-positive cells from AML patients with a high percentage of MPO-positive blasts. Taken together, the results of the present study indicate that MPO may serve as an informative marker for identifying a distinct and crucial DNA methylation profile in CD34-positive AML cells.

Application of a medium-energy collimator for I-131 imaging after ablation treatment of differentiated thyroid cancer

PURPOSE

High-energy (HE) collimators are usually applied for I-131 imaging after ablation treatment of differentiated thyroid cancer (DTC). However, purchase of HE collimators has been avoided in many nuclear medicine departments because the HE collimators are more expensive than other collimators. In this study, we compared the I-131 imaging using HE- and medium-energy (ME) collimators, which is more versatile than HE collimators.

MATERIALS AND METHODS

To simulate DTC patients with extra-thyroid beds, a phantom of acrylic containers containing I-131 was used. To simulate patients with thyroid beds, four phantoms representing extra-thyroid beds were arranged around the phantom representing normal thyroid tissues. Patients administered 1.11 or 3.70 GBq NaI-131 were also evaluated. Whole-body imaging and SPECT imaging of the phantoms and patients performed using HE-general-purpose (HEGP) and ME-low-penetration (MELP) collimators, and full-width at half maximum (FWHM) and percent coefficient of variation (%CV) were measured.

RESULTS

In the extra-thyroid beds, FWHM and %CV with MELP were negligibly different from those with HEGP in whole-body imaging. Although FWHM with MELP was a little different from that with HEGP in SPECT imaging, %CV with MELP was significantly higher than that with HEGP. In the thyroid beds, only an extra-thyroid bed including higher radioactivity was identified in whole-body imaging with both collimators. Although SPECT images with MELP could not clarify extra-thyroid beds with low radioactivity, HEGP could identify them. In patients, although some whole-body images with MELP could not detect extra-thyroid beds, whole-body imaging with HEGP and SPECT imaging with both collimators could detect them.

CONCLUSIONS

Although HEGP is the best collimator for I-131 imaging, MELP is applicable for not only whole-body imaging but also SPECT imaging.

[Technical features and roles of cobalt-57 flood sources for daily quality control of gamma cameras]

Quality control (QC) detects changes in the performance of gamma cameras that could adversely affect interpretations of clinical studies. We used plate and sheet (57)Co flood sources to measure extrinsic uniformity during daily QC. Each source, when placed on the top of a collimated detector, allowed the acquisition of uniform images from both detectors, thus reducing the amount of time needed to perform daily QC. No serious problems with the gamma camera system were revealed by visual checks, and changes in detector sensitivity were rapidly determined by observing daily variations in the measured values of extrinsic uniformity. Furthermore, (57)Co flood sources confer advantages in that they shorten the time required for preparation of flood sources and reduce the consequent exposure of medical staff to radiation.

[Bilateral filter applied to bone scintigraphy]

The aim of this study is to improve the image quality using a post process rather than a correction process at acquisition time. We used a smoothing filter that is widely used on a compact digital camera. Especially for nuclear medicine, when we use a short acquisition time, we will get images that have a large increase in statistical noise. For those images, we validated the efficiency of the smoothing filter by assessing two characteristic parameters. In addition, we defined the best smoothing filter parameters to get stable images that reduced the influence of statistical noise.

Prototype imaging protocols for monitoring the efficacy of iodine-131 ablation in differentiated thyroid cancer

Whole-body and single photon emission tomography (SPET) images during sodium iodide-131 (Na131I) ablation are useful to confirm the efficacy of ablation using 131I imaging. However, there have been no attempts to improve the quality of 131I imaging. We therefore investigated imaging protocols for 131I imaging in differentiated thyroid cancer (DTC). Phantoms containing 131I were used to simulate extra-thyroid beds and thyroid beds. To simulate extra-thyroid beds, a phantom containing 0.19, 0.37, 0.74 or 1.85 MBq was placed in the acquisition center. To simulate the thyroid beds, four phantoms were applied as normal thyroid tissue, and four phantoms containing 0.19, 0.37, 0.74 and 1.85 MBq were arranged around normal thyroid tissue as a cancer. Whole-body imaging was performed at different table speeds, and SPET data acquired with various pixel sizes were reconstructed using a filtered backed projection (FBP) and ordered-subsets expectation maximization with 3-dimensional (OSEM-3D) algorithm. We measured full width at half maximum (FWHM) and % coefficient of variation (%CV). Patients were then examined based on the results of phantom studies. In extrathyroid beds, slower table speed in whole-body imaging improved %CV, but had little effect on FWHM. For SPET imaging OSEM-3D produced high-resolution and low-noise images, and FWHM and %CV improved with smaller pixel size, as compared with FBP. In the thyroid beds, only the 1.85 MBq phantom could be confirmed on whole-body imaging. Images by SPET had high FWHM and low %CV when the smaller pixel size and OSEM-3D were applied. Accumulation of ≤1.85 MBq was detected with a smaller pixel size of ≤4.8 mm and OSEM-3D. For Na131I ablation imaging, slower scan speed is suitable for whole-body imaging and smaller pixel size and OSEM-3D is appropriate for SPET imaging. In conclusion, we confirmed Na131I accumulation in thyroid beds using slower scan speed (≤15 cm/min) on whole-body imaging, and then accurate identification of Na131I accumulation using SPET and CT fusion imaging with smaller pixel size (≤4.8 mm) and OSEM-3D.

[Usefulness of nuclear medicine extension code keeping the integrity with JJ1017]

OBJECTIVE

Working group on JJ1017 nuclear medicine domain extension code in the Japanese Society of Nuclear Medicine has created nuclear medicine extension codes keeping the integrity with JJ1017. The objective of this study was to investigate the usefulness of nuclear medicine extension codes in real clinical settings.

METHOD

Nuclear medicine examinations of each institution were extracted from the examination master table and then the target subset of examinations to be coded with JJ1017 were identified. For this subset, working process was conducted, during which the followings compared conformity rate, application rate of representative frequently code set and compliance rate of nuclear medicine extension codes.

RESULTS

Without using representative frequently code set, it was difficult to invent the same code for the same examination. By using the representative frequently code set, the same code expression could be invented for the same examination. Furthermore, using nuclear medicine extension codes additionally, these which could not be appropriately coded with representative frequently code set alone.

CONCLUSION

Nuclear medicine extension codes keeping the integrity with JJ1017, was proved to be useful to improve the accuracy of coding.

Subcutaneous Extravasation of Sr-89: Usefulness of Bremsstrahlung Imaging in Confirming Sr-89 Extravasation and in the Decision Making for the Choice of Treatment Strategies for Local Radiation Injuries Caused by Sr-89 Extravasation

A male patient in his 20s presented at our clinic with pain caused by bone metastases of the primitive neuroectodermal tumor, and Sr-89 was administrated to palliate the pain. After receiving the injection, the patient complained of a slight burning pain at the catheterized area. Slight reddening and small circular swelling (diameter, 0.5 cm) were observed at the catheterized area. Sr-89 extravasation was suspected. To estimate the amount of subcutaneous Sr-89 leakage, bremsstrahlung imaging was immediately performed. We speculated that the skin-absorbed dose from subcutaneous infiltration of Sr-89 was 1.78 Gy. The mildest clinical sign of local radiation injury was erythema. The received dose was higher than 3 Gy, and the time of onset was from 2 to 3 weeks. In our patient, local radiation injuries (LRIs) did not occur. Though requiring further verification, subsequent bremsstrahlung imaging and estimation of the skin-absorbed dose from the subcutaneous infiltration of Sr-89 are useful in confirming Sr-89 extravasation and in the decision making for the choice of treatment strategies for LRIs caused by Sr-89 extravasation.

Towards excimer-laser-based stereolithography: a rapid process to fabricate rigid biodegradable photopolymer scaffolds

We demonstrate high-resolution photocross-linking of biodegradable poly(propylene fumarate) (PPF) and diethyl fumarate (DEF) using UV excimer laser photocuring at 308 nm. The curing depth can be tuned in a micrometre range by adjusting the total energy dose (total fluence). Young's moduli of the scaffolds are found to be a few gigapascal, high enough to support bone formation. The results presented here demonstrate that the proposed technique is an excellent tool for the fabrication of stiff and biocompatible structures on a micrometre scale with defined patterns of high resolution in all three spatial dimensions. Using UV laser photocuring at 308 nm will significantly improve the speed of rapid prototyping of biocompatible and biodegradable polymer scaffolds and enables its production in a few seconds, providing high lateral and horizontal resolution. This short timescale is indeed a tremendous asset that will enable a more efficient translation of technology to clinical applications. Preliminary cell tests proved that PPF : DEF scaffolds produced by excimer laser photocuring are biocompatible and, therefore, are promising candidates to be applied in tissue engineering and regenerative medicine.

[Multi-center study of inter-scanner difference in brain positron emission tomography]

We showed scanner dependence of brain (18)F-FDG and (11)C-PiB images by using phantom examination with nine kinds of positron emission tomography (PET) scanners. We used two types of phantoms, cylindrical phantom with 15 cm inside diameter and three-dimensional (3D) brain phantom, and we set the body phantom on the bed to examine the effect of scatter and random coefficients from outside of the axial field of view (AFOV). Radioactivity and distance of the two phantoms were determined by a pilot study to obtain a condition similar to the clinical study. Axial uniformity was evaluated by circular region of interest (ROI) of 12 cm diameter, set in the center of the reconstruction image of the cylindrical phantom. As a result, the standardized uptake value (SUV) was lower than the true value in some scanners, and there was a scanner in which the axial uniformity was deteriorated by high radioactivity outside the AFOV. In the cylindrical phantom, the axial uniformity of the scanner was improved using the new dead-time correction method; however, it was not improved in the 3D brain phantom. Quality-controlled PET scanners are important to maintain constant levels for multicenter studies.

Human herpes virus 8-negative primary effusion lymphoma with BCL6 rearrangement in a patient with idiopathic CD4 positive T-lymphocytopenia

Primary effusion lymphoma (PEL) was initially designated as a body-cavity-based lymphoma and recognized as a distinct clinical entity without a contiguous tumor mass. PEL was first reported in patients with acquired immunodeficiency syndrome (AIDS) and the distinctive feature of PEL originally reported as a B-cell neoplasm characterized by infection of the tumor cells by human herpes virus 8 (HHV-8). However, there have recently been several reports of PEL in patients without human immunodeficiency virus (HIV) or HHV-8 infection.

Expression of myeloperoxidase enhances the chemosensitivity of leukemia cells through the generation of reactive oxygen species and the nitration of protein

Myeloperoxidase (MPO), a pivotal lineage marker for acute myeloid leukemia (AML), has been also shown to have a prognostic value: a high percentage of MPO-positive blasts correlates to favorable prognosis. To understand the relationship between the expression of MPO in leukemia cells and the response to chemotherapeutic agents, we established MPO-expressing K562 leukemia cell lines and then treated them with cytosine arabinocide (AraC). Cells expressing wild-type MPO, but not mutant MPO that could not mature, died earlier of apoptosis than control K562 cells. Reactive oxygen species (ROS) were generated more in leukemia cells expressing MPO, and the generation was abrogated by MPO inhibitors or antioxidants. Tyrosine nitration of cellular protein also increased more in MPO-expressing K562 cells than control cells after treatment with AraC. In clinical samples, CD34-positive AML cells from high-MPO cases showed a tendency to be sensitive to AraC in the colony-formation assay, and the generation of ROS and the nitration of protein were observed only when the percentage of MPO-expressing cells was high. These data suggest that MPO enhances the chemosensitivity of AML through the generation of ROS and the nitration of proteins.

Gallium scintigraphy in a case of tuberculous trochanteric bursitis

We report a 67-year-old woman with systemic lupus erythematosus and systemic disseminated tuberculosis affecting the femoral trochanteric bursae, a site rarely affected by tuberculosis. For quantification of the inflammation with gallium-67 scintigraphy, we calculated the radioisotope count ratio in the most inflamed areas, the right lateral thorax and bursa of the right greater trochanter. Systemic scanning with this modality allowed evaluation of the extent of lesions and simple quantitative determination of the severity of inflammation, yielding information useful for the follow-up of the patient during the course of tuberculosis treatment.

A case of sclerosing cholangitis with autoimmune pancreatitis evaluated by FDG-PET

The extrapancreatic bile duct lesions in autoimmune pancreatitis are termed sclerosing cholangitis (SC with AIP), which is known to complicate AIP somewhat more frequently than other extrapancreatic lesions. In cases of SC with AIP, differentiation from primary SC, pancreatic cancer, and bile duct cancer is often difficult. In our patient, pancreatic cancer had to be ruled out at admission, given the findings of obstructive jaundice, pancreatic duct stenosis, and swelling of the pancreas. Fluorine-18-fluorodeoxyglucose positron emission tomography was useful in checking for the presence of extrapancreatic lesions, including SC, and was also useful in the evaluation of the response to steroid therapy for following the course of AIP.

Detection of local residual tumor after laryngeal cancer treatment using FDG-PET

OBJECTIVE

Fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) is sometimes used as a means of follow-up after diagnosis and treatment of cancers of the head and neck region. The present study was undertaken to evaluate the ability of FDG-PET to detect local residual tumor after treatment of laryngeal cancer.

METHODS

Thirty-six patients with laryngeal cancer underwent FDG-PET before and after initial treatment. Of these patients, 20 received FDG-PET before treatment and 28 received it after treatment. The relationship between standardized uptake values (SUV) and the presence or absence of local residual tumor was investigated by setting the cut-off value of the SUV using the receiver operating characteristics (ROC) curve.

RESULTS

When the pre-treatment SUV threshold for laryngeal cancer was set at 7.20, the detection of local residual tumor after treatment using FDG-PET had a sensitivity of 77.78%, specificity of 81.82%, false positive rate of 18.18%, false negative rate of 22.22%, accuracy of 80% and a p value of 0.02. When the post-treatment SUV threshold for the larynx was set at 3.35, the test had a sensitivity of 93.75%, specificity of 91.67%, false positive rate of 8.33%, false negative rate of 6.25%, accuracy of 92.86% and a p value of 0.0001.

CONCLUSIONS

FDG-PET was found to be useful for determining the presence of local residual tumor after treatment of laryngeal cancer.

Small number of HTLV-1-positive cells frequently remains during complete remission after allogeneic hematopoietic stem cell transplantation that are heterogeneous in origin among cases with adult T-cell leukemia/lymphoma

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) can provide long-term remission for patients with adult T-cell leukemia/lymphoma (ATLL) caused by human retrovirus, human T-lymphocyte virus (HTLV-1). To understand how HTLV-1-positive cells including ATLL cells were suppressed by allo-HSCT, we examined HTLV-1 provirus load and residual ATLL cells in peripheral blood of transplant recipients using PCR-based tests. We found that the copy number of HTLV-1 genome, called provirus, became very small in number after allo-HSCT; however, in most cases, provirus did not disappear even among long-term survivors. Tumor-specific PCR tests demonstrated that most of HTLV-1-positive cells that remained long after transplantation were not primary ATLL cells but donor-derived HTLV-1-positive cells. We also found a case having very low amount of residual disease in peripheral blood even long after transplantation. There was only one recipient in whom we failed to show the presence of HTLV-1 genome and antibody against HTLV-1 even with an extensive search, which strongly suggested the elimination of HTLV-1 after allo-HSCT. These results demonstrated that after allo-HSCT the small amount of residual HTLV-1-positive cells were heterogeneous in origin and that long-term disease control for ATLL could be obtained without the complete elimination of HTLV-1.

Improvement of criteria for refractory cytopenia with multilineage dysplasia according to the WHO classification based on prognostic significance of morphological features in patients with refractory anemia according to the FAB classification

In the criteria of refractory cytopenia with multilineage dysplasia (RCMD) according to the WHO (World Health Organization) classification, the frequency threshold concerning dysplasia of each lineage was defined as 10%. To predict overall survival (OS) and leukemia-free survival (LFS) for patients with refractory anemia (RA) according to the French-American-British (FAB) classification, we investigated prognostic factors based on the morphological features of 100 Japanese and 87 German FAB-RA patients, excluding 5q-syndrome. In the univariate analysis of all patients, pseudo-Pelger-Huet anomalies >or=10% (Pelger+), micromegakaryocytes >or=10% (mMgk+), dysgranulopoiesis (dys G) >or=10% and dysmegakaryopoiesis (dys Mgk) >or=40% were unfavorable prognostic factors for OS and LFS (OS; P<0.001, LFS; P<0.001). The prognostic effects of the morphological features were similar in both Japanese and German patients. However, dys Mgk >or=10% was not correlated with OS and LFS. In the multivariate analysis, mMgk+ and dys Mgk>or=40% were adverse prognostic factors for OS for all patients, and dys G >or=10% and dys Mgk>or=40% were adverse prognostic factors for LFS for all patients. On the basis of the present analysis, we propose the following modified morphological criteria for RCMD. Modified RCMD should be defined as FAB-RA, excluding 5q-syndrome with dys G >or=10%, dys Mgk>or=40% or mMgk+.

Advantages of upright position imaging with medium-energy collimator for sentinel node lymphoscintigraphy in breast cancer patients

OBJECTIVE

To evaluate the advantage of upright position imaging with a medium-energy collimator for the detection of sentinel lymph node (SLN).

METHODS

Thirty-four patients with operable breast cancer underwent sentinel node lymphoscintigraphy with 99mTc-tin colloid. Images were obtained in 5 different positions and paired images from the same patient were compared using side-by-side interpretation. Images were compared in 3 groups: group 1 (anterior view); supine (SAV) vs. upright (UAV), group 2 (oblique view); supine (SOV) vs. upright (UOV), and group 3 (oblique view); modified supine (MOV) vs. UOV. Image quality was evaluated using a 3-grade scale of clear, faint, and equivocal depiction, and correlated to 3 parameters: distance from injection site to lymph node (hot node), counts in hot node, and image contrast. Parameters in group 1 were compared by classifying the primary tumor site into 4 subregions.

RESULTS

Image quality in all 3 groups was more enhanced on the image obtained in the upright position than that in the supine position. Obtaining images in an upright position increased the mean distances by 1.5-3.2 cm, and mean contrasts were significantly increased by 0.13-0.31 (p < 0.05). It was shown that image quality was more greatly affected by image contrast than by counts in the hot node. Image contrast of 0.5 seemed an appropriate threshold level for detection of the hot node. On comparison of tumor sites, the upper outer quadrant (C) region of the 4 subregions demonstrated greater contrast enhancement on upright position images.

CONCLUSION

Clinical images obtained in an upright position with a medium-energy collimator were superior to those obtained in a supine position. Use of this procedure is recommended to enhance lymph node detection on sentinel node lymphoscintigraphy.

A case of hepatic inflammatory pseudotumor identified by FDG-PET

A 53-year-old man with a history of nausea and elevated liver functions presented to our clinic. A CT scan showed a small tumor in the right lobe of the liver. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography confirm abnormal metabolic activity with a high standardized uptake value of 7.3 in the lesion. These findings could indicate a malignancy such as well-differentiated hepatocellular carcinoma or cholangiocarcinoma, or a benign lesion such as hepatic abscess. He was diagnosed by histopathological examination as having an epithelioid granuloma with many inflammatory cells. This is the rare report of hepatic inflammatory pseudotumor featuring markedly increased 18F-FDG uptake.

Usefulness of medium-energy collimator for sentinel node lymphoscintigraphy imaging in breast cancer patients

This study was performed to investigate the usefulness of a general-purpose medium-energy (ME) collimator for the accurate localization of the sentinel lymph node (SLN) in breast cancer patients.

METHODS

We compared phantom images and lymphoscintigraphy images obtained under different conditions for a patient with breast cancer. Comparisons were performed between 2 cameras, between a low-energy high-resolution (LEHR) collimator and a general-purpose ME collimator, and between energy windows centered at 141 keV and at 146 keV. Profile curves and image contrast were evaluated along with the visual interpretation of images. The most suitable imaging time was selected from the relationship between contrast and the data acquisition time.

RESULTS

The images obtained with the general-purpose ME collimator and the energy window centered at 141 keV were of poorer quality than those obtained with the LEHR collimator and the same energy window. However, the quality of the images obtained with the general-purpose ME collimator improved when the energy window was centered at 146 keV. The method involving the general-purpose ME collimator and the energy window centered at 146 keV showed excellent image quality similar to that obtained with the LEHR collimator. The enhancement of contrast was confirmed at more than 3 cm away from the center of the injection site. Stable contrast was obtained with a data acquisition time of 5 min, with the general-purpose ME collimator, and with the energy window centered at 146 keV.

CONCLUSION

The method involving the general-purpose ME collimator and the energy window centered at 146 keV has the merit of the lymph node not being concealed by a lead shield. This new method is expected to improve the rate of detection of SLN and has the potential for shortening the acquisition time.

Fusion of SPECT and multidetector CT images for accurate localization of pelvic sentinel lymph nodes in prostate cancer patients

OBJECTIVE

The present study was performed to investigate the feasibility of fusion of images obtained by SPECT and multidetector CT (MDCT) for the accurate localization of sentinel lymph nodes in prostate cancer patients.

METHODS

To facilitate the fusion of both SPECT and CT images, a pelvic MDCT scan was performed with 3 markers of small plastic bullets attached to the skin over the bilateral iliac crests and the ventral midline at the same height. SPECT was performed after the same locations were marked with needle caps containing (99m)Tc-pertechnetate. The images were superimposed by use of free software (MRIcro). The results of hot lymph node detection with fusion images were compared with those of surgery.

RESULTS

The images could be successfully superimposed for all 11 patients examined. Surgeons accurately confirmed 27 (87.1%) of 31 regional lymph nodes on fusion images.

CONCLUSION

Fusion of SPECT and MDCT images is useful for the precise localization of sentinel lymph nodes in prostate cancer patients.

[Usefulness of imaging method without using lead plate for sentinel lymph node scintigraphy]

PURPOSE

In scintigraphy of the sentinel lymph node, it is common to use a lead plate as a shield to reduce star artifact and scattered radiation in the portion surrounding the injected site of radioactive colloid. We have developed an imaging method without using a lead plate, and examined its usefulness in phantom and clinical imagings.

METHODS, RESULTS

Star artifact was eliminated using a medium energy collimator. Effects of scattered radiation from the injection site were reduced by setting energy window at higher level.

CONCLUSIONS

Our method without using a lead plate can be applied to dynamic data acquisition and imaging of a portion where it is difficult to place a lead plate. It also seems to be a useful imaging method in that it takes patients' feelings into consideration.

Circulating transforming growth factor beta 1 as a predictor of liver metastasis after resection in colorectal cancer

Plasma transforming growth factor beta1 (TGF-beta1) has been reported to be correlated with the extent of disease in colorectal cancer, but it is not known whether measuring this cytokine can help predict liver metastasis after curative resection. We prospectively studied whether plasma TGF-beta1 levels could predict liver metastasis in 117 patients with colorectal cancer before and after curative resection. Blood samples were drawn before and 2 weeks after surgery to determine the cytokine levels. Abdominal ultrasonography or computed tomography was done every 3 months after surgery. The primary end point for follow-up was recurrence. Seventy-seven of 117 cases (66%) had preoperative levels of the cytokine higher than the borderline limit of 7.5 ng/ml. Postoperative levels were >7.5 ng/ml in 29 of 117 patients (25%). The median follow-up period was 42 months (range, 5--66 months), with follow-up of all 117 patients. No recurrence was observed in 13 patients with Dukes' stage A lesions. Liver metastasis occurred in 18 of 104 patients (17%) with Dukes' stage B or C disease. Fourteen of 18 patients (78%) who developed liver metastasis had shown a postoperative plasma TGF-beta1 level of >7.5 ng/ml. Cox proportional hazards regression analysis showed that the postoperative level was a significant predictive factor for liver metastasis (P < 0.001). A single point measurement of plasma TGF-beta1 levels at 2 weeks after curative resection seems to be able to predict liver metastasis in colorectal cancer. This finding suggests the value of a prospective trial of liver-targeted adjuvant therapy for patients with elevated postoperative plasma TGF-beta1 levels.

Involvement of protein kinase C and tyrosine kinase in lipopolysaccharide-induced anorexia

Injections of lipopolysaccharide (LPS, 3 microg) into the lateral ventricle elicited anorexia with fever and also decreased body weight in rats. The LPS-induced anorexia was inhibited by intracerebroventicular (i.c.v.) injections of anti-interleukin (IL)-1beta antibody (Ab), chelerythrine, genistein and tyrphostin 46, but not by injections of indomethacin. Consecutive injections of orthovanadate and LPS (0.3 microg, a dose of LPS that did not show any effect on food intake, body weight or body temperature) reduced body weight, but did not induce anorexia. On the other hand, injections of IL-1beta (50 ng) did not influence food intake, although they decreased body weight and produced fever. The IL-1beta-induced decrease in body weight was inhibited by injections of genistein, but not by injections of chelerythrine or indomethacin. These findings suggest that the LPS-induced anorexia is independent of hyperthermia and involves IL-1beta generation, tyrosine kinase (TK) and protein kinase C (PKC). This is the first in vivo evidence that activation of TK and PKC induced by LPS is linked to anorexia.

Identification of a novel cytokine response element in the human IFN regulatory factor-1 gene promoter

The present study investigates the regulatory mechanisms involved in the cooperation between IFN-gamma and TNF-alpha to promote transcription from IFN regulatory factor-1 (IRF-1). A transient transfection analysis revealed that the region between -218 and -144, where +1 is the transcription start site, as well as previously reported downstream elements, ppkappaB and IFN-gamma activation site/kappaB, were required for the optimal response to the two cytokines. A subsequent DNase I footprint analysis showed that the region between -171 and -144 was inducibly protected with stimulation by TNF-alpha, and this protection was significantly enhanced with the combination of IFN-gamma and TNF-alpha. In an EMSA with the protected region as a probe, a TNF-alpha-inducible complex (C1) and an IFN-gamma-inducible complex (C2), but no synergy-specific DNA-protein complexes, were recognized. The C1 complex consisted of a pre-existing factor (p65/p50), whereas the C2 complex consisted of a newly synthesized IRF-1-related factor. A methylation interference assay revealed the critical G residues (from -167 to -151) for the DNA-protein complex formation specific to the cytokine response, and within this region the novel kappaB sequence, the promoter distal kappaB (pdkappaB) element (5'-GGGGAAG TAC-3'), was identified. Because the base substitutions over the pdkappaB region (from -171 to -144) affected not only the TNF-alpha-response but also that of IFN-gamma, this region might contribute to the cooperative action of the NF-kappaB subunits with the IRF-1-related factor. Finally, we demonstrated that none of the cis-acting elements, ppkappaB, pdkappaB, or IFN-gamma activation site/kappaB, is dispensable for the optimal synergism in response to IFN-gamma and TNF-alpha.

Activation of Rho signaling contributes to lysophosphatidic acid-induced contraction of intact ileal smooth muscle of guinea-pig

To elucidate the possible role of Rho A/Rho-kinase on lysophosphatidic acid (LPA)-induced contraction in intact guinea-pig ileal smooth muscle, we examined effects of pretreatment with a specific inhibitor of Rho-kinase (Y-27632) on the LPA-induced contraction and MLC20 phosphorylation. In addition, we investigated whether LPA actually elicits an activation of Rho A by studying subcellular distribution of Rho A in unstimulated and stimulated smooth muscles by LPA. LPA induced a less intense, but sustained, contraction compared with ACh, and was accompanied by significant increases in MLC20 phosphorylation. The effects of LPA on tension and MLC20 phosphorylation were inhibited by Y-27632. The ACh-induced contraction, but not increases in MLC20 phosphorylation, was partially inhibited by Y-27632. High K+-induced contraction was unaffected by the inhibitor. LPA stimulated translocation of Rho A from the cytosol to the membrane fraction of the muscle. Translocation of Rho A was also induced by ACh and high K+. These results suggest that LPA-induced contraction of intact ileal smooth muscle is dominated through activation of Rho A and Rho-kinase and subsequent increases in MLC20 phosphorylation.