Prediction of Microsatellite Instability in Colorectal Cancer Using a Machine Learning Model Based on PET/CT Radiomics

Purpose@#We investigated the feasibility of preoperative 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/ computed tomography (CT) radiomics with machine learning to predict microsatellite instability (MSI) status in colorectal cancer (CRC) patients. @*Materials and Methods@#Altogether, 233 patients with CRC who underwent preoperative FDG PET/CT were enrolled and divided into training (n=139) and test (n=94) sets. A PET-based radiomics signature (rad_score) was established to predict the MSI status in patients with CRC. The predictive ability of the rad_score was evaluated using the area under the receiver operating characteristic curve (AUROC) in the test set. A logistic regression model was used to determine whether the rad_score was an independent predictor of MSI status in CRC. The predictive performance of rad_score was compared with conventional PET parameters. @*Results@#The incidence of MSI-high was 15 (10.8%) and 10 (10.6%) in the training and test sets, respectively. The rad_score was constructed based on the two radiomic features and showed similar AUROC values for predicting MSI status in the training and test sets (0.815 and 0.867, respectively; p=0.490). Logistic regression analysis revealed that the rad_score was an independent predictor of MSI status in the training set. The rad_score performed better than metabolic tumor volume when assessed using the AUROC (0.867 vs. 0.794, p=0.015). @*Conclusion@#Our predictive model incorporating PET radiomic features successfully identified the MSI status of CRC, and it also showed better performance than the conventional PET image parameters.

Multimodal Imaging Findings of Cerebral Amyloid Angiopathy Related Inflammation With Unusual Clinical Manifestation: A Case Report

Cerebral amyloid angiopathy-related inflammation (CAA-RI) is a rare encephalopathy characterized by the coexistence of a perivascular inflammatory reaction in patients with cerebral amyloid angiopathy. CAA-RI diagnosis is challenging as its final diagnosis requires invasive procedures such as autopsy or brain biopsy. Therefore, multimodal imaging approaches with clinical considerations are essential for the probable diagnosis of CAA-RI. In particular, in the case of CAA-RI presented with uncommon clinical symptoms, the need for imaging in diagnosis is further highlighted by difficulties of clinical approaches. Herein, we report a case of CAA-RI with unusual clinical manifestation diagnosed using multimodal imaging including magnetic resonance imaging (MRI) and amyloid positron emission tomography-computed tomography (PET-CT). Multimodal imaging approaches using adequate MRI sequences and PET-CT scans could facilitate the diagnosis of CAA-RI without requiring invasive pathological confirmation.

Tau Positron Emission Tomography Imaging in Degenerative Parkinsonisms

In recent years, several radiotracers that selectively bind to pathological tau proteins have been developed. Evidence is emerging that binding patterns of in vivo tau positron emission tomography (PET) studies in Alzheimer's disease (AD) patients closely resemble the distribution patterns of known neurofibrillary tangle pathology, with the extent of tracer binding reflecting the clinical and pathological progression of AD. In Lewy body diseases (LBD), tau PET imaging has clearly revealed cortical tau burden with a distribution pattern distinct from AD and increased cortical binding within the LBD spectrum. In progressive supranuclear palsy, the globus pallidus and midbrain have shown increased binding most prominently. Tau PET patterns in patients with corticobasal syndrome are characterized by asymmetrical uptake in the motor cortex and underlying white matter, as well as in the basal ganglia. Even in the patients with multiple system atrophy, which is basically a synucleinopathy, ¹⁸F-flortaucipir, a widely used tau PET tracer, also binds to the atrophic posterior putamen, possibly due to off-target binding. These distinct patterns of tau-selective radiotracer binding in the various degenerative parkinsonisms suggest its utility as a potential imaging biomarker for the differential diagnosis of parkinsonisms.

Increased Uptake of AV-1451 in a Subacute Infarction Lesion

¹⁸F-AV-1451 is a tau PET ligand that has high affinity for paired helical filament tau. However, various off-target bindings unrelated to tau have also been reported. Herein, we report a case of 83-year-old woman, who showed abnormal uptake of AV-1451 that was shown to be subacute infarction. Clinicians should recognize that increased uptake of AV-1451 may be related to stroke.

Chronic Myeloid Leukemia Following Radioactive Iodine Treatment for Thyroid Cancer: Two Case Reports and a Literature Review / 대한내과학회지

The incidence of thyroid cancer has increased rapidly worldwide, although most patients can survive for a long time without developing symptoms. While most thyroid cancers are treated with thyroidectomy alone, some patients are given additional radioactive iodine (RAI) in the form of 131I to treat thyroid cancer metastasis. RAI is associated with acute and chronic complications. Secondary malignancies are the most important in long-term cancer survivors. While many studies have reported the occurrence of acute myeloid leukemia after high-dose RAI, there are few reports on chronic myeloid leukemia (CML) after low-dose RAI treatment. Moreover, previous cases of CML following thyroid cancer were reported before the tyrosine kinase inhibitor (TKI) era. Here, we describe two cases of CML following thyroid cancer that were successfully treated with second-generation TKIs.

A Computed Tomography-Based Spatial Normalization for the Analysis of 18F Fluorodeoxyglucose Positron Emission Tomography of the Brain

OBJECTIVE: We developed a new computed tomography (CT)-based spatial normalization method and CT template to demonstrate its usefulness in spatial normalization of positron emission tomography (PET) images with [18F] fluorodeoxyglucose (FDG) PET studies in healthy controls. MATERIALS AND METHODS: Seventy healthy controls underwent brain CT scan (120 KeV, 180 mAs, and 3 mm of thickness) and [18F] FDG PET scans using a PET/CT scanner. T1-weighted magnetic resonance (MR) images were acquired for all subjects. By averaging skull-stripped and spatially-normalized MR and CT images, we created skull-stripped MR and CT templates for spatial normalization. The skull-stripped MR and CT images were spatially normalized to each structural template. PET images were spatially normalized by applying spatial transformation parameters to normalize skull-stripped MR and CT images. A conventional perfusion PET template was used for PET-based spatial normalization. Regional standardized uptake values (SUV) measured by overlaying the template volume of interest (VOI) were compared to those measured with FreeSurfer-generated VOI (FSVOI). RESULTS: All three spatial normalization methods underestimated regional SUV values by 0.3-20% compared to those measured with FSVOI. The CT-based method showed slightly greater underestimation bias. Regional SUV values derived from all three spatial normalization methods were correlated significantly (p < 0.0001) with those measured with FSVOI. CONCLUSION: CT-based spatial normalization may be an alternative method for structure-based spatial normalization of [18F] FDG PET when MR imaging is unavailable. Therefore, it is useful for PET/CT studies with various radiotracers whose uptake is expected to be limited to specific brain regions or highly variable within study population.

Knowledge, Self-Efficacy, and Perceived Barriers on the Low-Iodine Diet among Thyroid Cancer Patients Preparing for Radioactive Iodine Therapy

The purposes of the study were to assess knowledge, self-efficacy, and perceived barriers on a low-iodine diet among thyroid cancer patients and to identify strategies for nutrition education. A self-administered questionnaire was developed based on a review of literature and pilot-tested. A total of 121 female thyroid cancer patients participated in a survey and 117 responses were used for data analysis. An average knowledge score of the thyroid cancer patients was 4.5 point (available score: 0-10 point). Majority of the respondents knew that seaweeds such as lavers, brown seaweeds, and sea tangles contain large amount of iodine. However they mistook the low iodine diet as a low salt diet and were not aware of foods and seasonings that are allowed on the low iodine diet. While self-efficacy related to consuming various fruits and vegetables, to choosing potatoes and sweet potatoes for snacks, and restricting consumption of eggs, milk and milk products, and processed foods was rated highly, self-efficacy for preparing foods without using sea salts was rated low. The self-efficacy score increased as their interest on the dietary life and perceived cooking skills were greater. Most perceived barriers toward practicing the low iodine diet were related to preparation of the low iodine menus. As their interest in the dietary life and cooking and perceived cooking skills were greater, the patients perceived barriers on practicing the low iodine diet less. While the patients showed higher self-efficacy and lower barrier perception on selecting foods low in iodine and restricting food high in iodine, they showed lower self-efficacy and higher barrier perceptions on preparing low iodine meals. Clinical dietitians should recognize the gap between what the patients should know and what they really know and identify strategies on how to improve self-efficacy and reduce perceived barriers on the low iodine diet. Recent literature and the findings of the study reveal that incorporating cooking classes into nutrition education for thyroid patients is effective to enhance self-efficacy and to reduce perceived barriers on the low iodine diet.

A Spinal Cord Astrocytoma and Its Concurrent Osteoblastic Metastases at the Time of the Initial Diagnosis: a Case Report and Literature Review

Bone metastasis from a spinal cord astrocytoma has been reported only twice in the English medical literature. It is generally known that bone metastasis is found after the initial diagnosis with/without intervening surgery rather than being found at the time of the diagnosis of astrocytoma. The purpose of this article is to report for the first time a case of concurrent bone metastasis from a spinal cord astrocytoma at the time of diagnosing the spinal cord astrocytoma.

Abnormal Cerebral Benzodiazepine Receptors Binding Measured with (123)I-Iomazenil SPECT in Panic Disorder / 신경정신의학

OBJECTIVES: Researchers have long hypothesized that the benzodiazepine-GABA system plays a role in the pathophysiology of panic disorder (PD). However, previous neuroimaging studies have been inconclusive, possibly due to matching discrepancies between patients and controls, confounding medication factors, and/or image analyzing methods. This study aimed to compare benzodiazepine receptor binding between PD patients and healthy controls. METHODS: Via (123)I-iomazenil single-photon emission computed tomography (IMZ-SPECT), we obtained regional brain patterns of benzodiazepine receptor binding for 12 unmedicated PD patients and 8 healthy age-and sex-matched volunteer controls. To analyze the image data, we used statistical parametric mapping (SPM). RESULTS: Benzodiazepine receptor binding showed a decrease in both the parietal and occipital lobes in PD patients as compared to controls. The anterior cingulate cortex, left parahippocampal gyrus, and both temporal lobes showed increased binding in PD patients. CONCLUSION: Our findings provide evidence of an abnormal BZD-GABA system in PD patients, suggesting that basal and/or compensatory changes in inhibitory neurotransmissions contribute to the pathogenesis of human PD.

Differentiation of Parkinson's Disease and Essential Tremor on I-123 IPT(I-123-N-(3-iodopropen-2-yl)-2beta-carbomethoxy-3beta(4-cholorophenyl) tropane) Brain SPECT / 핵의학분자영상

PURPOSE: The study was to assess I-123-N-(3-iodopropen-2-yl)-2[beta]-carbomethoxy-3[beta]-(4-cholorophenyl) tropane (IPT) SPECT in differential diagnosis among early stage of Parkinson's disease(PD) and essential tremor(ET) and normal control(NL) groups quantitatively. MATERIALS AND METHODS: I-123 IPT brain SPECT of 50 NL, 20 early PD, 30 advanced PD, and 20 ET were performed at 20 minutes and 2 hours. Specific/nonspecific binding of striatum was calculated by using right and left striatal specific to occipital non-specific uptake ratio (striatum-OCC/OCC). RESULTS: Mean value of specific/nonspecific binding ratio was significantly different between advanced PD group and NL group. However, significant overlap of striatal specific/nonspecific binding ratio was observed between PD group and ET group. Bilateral striatal specific/nonspecific binding ratios were decreased in advanced PD. Lateralized differences in the striatal uptake of I-123 IPT correlated with asymmetry in clinical findings in PD group. CONCLUSION: I-123 IPT SPECT may be a useful method for the diagnosis of PD and objective evaluation of progress of clinical stages. Care should be made in the differential diagnosis of early stage of PD and other motor disturbances mimicking PD such as ET in view of significant overlap in striatal I-123 specific/nonspecific binding ratio.

F-18 FDG PET Features of Progressive Massive Fibrosis in Patients with Pneumoconiosis

PURPOSE: To evaluate the fluorodeoxyglucose positron emission tomography (FDG-PET) features of progressive massive fibrosis (PMF) in patients with pneumoconiosis. MATERIALS AND METHODS: FDG-PET and chest CT scans were performed in 11 patients with pneumoconiosis and PMF on chest radiographs. We evaluated the size, location, maximum, and mean of the standardized uptake value (SUV) for the PMF. A fine needle aspiration biopsy was performed in patients with a mean SUV of > 2.5 to exclude lung malignancies or pulmonary tuberculosis. A Pearson's correlation was performed to determine if a correlation exists if between the sizes and the mean SUV of the PMF. RESULTS: A total of 19 masses from 11 patients were located in the upper lobes (bilateral in eight and right in three). The sizes of the lesions ranged from 1.3 to 6.4 cm (mean = 3.6 cm). The maximum SUV was 0.5 to 8.1 (mean = 3.8) and the mean SUV was 0.4 to 5.9 cm (mean = 2.9 cm). Lung malignancies or tuberculosis were not identified in the 12 lesions (63%) with a mean SUV of >2.5. The sizes of the PMF did not correlate well with the mean SUV (r = 0.225). CONCLUSION: FDG-PET scans can show PMFs as regions of increased metabolic activity (mean SUV, 2.9) without evidence of lung cancer or pulmonary tuberculosis. No correlation between the sizes of PMF and the mean SUV was found.

Assessment of the Right Ventricular Function and Mass Using Cardiac Multi-Detector Computed Tomography in Patients with Chronic Obstructive Pulmonary Disease

OBJECTIVE: We wanted to assess the relationship between measurements of the right ventricular (RV) function and mass, with using cardiac multi-detector computed tomography (MDCT) and the severity of chronic obstructive pulmonary disease (COPD) as determined by the pulmonary function test (PFT). MATERIALS AND METHODS: Measurements of PFT and cardiac MDCT were obtained in 33 COPD patients. Using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, the patients were divided into three groups according to the severity of the disease: stage I (mild, n = 4), stage II (moderate, n = 15) and stage III (severe, n = 14). The RV function and the wall mass were obtained by cardiac MDCT. The results were compared among the groups using the Student-Newman-Keuls method. Pearson's correlation was used to evaluate the relationship between the right ventricular ejection fraction (RVEF) and the wall mass results with the PFT results. P-values less than 0.05 were considered statistically significant. RESULTS: The RVEF and mass were 47+/-3% and 41+/-2 g in stage I, 46+/-6% and 46+/-5 g in stage II, and 35+/-5% and 55+/-6 g in stage III, respectively. The RVEF was significantly lower in stage III than in stage I and II (p < 0.01). The RV mass was significantly different among the three stages, according to the disease severity of COPD (p < 0.05). The correlation was excellent between the MDCT results and forced expiratory volume in 1 sec (r = 0.797 for RVEF and r = -0.769 for RV mass) and forced expiratory volume in 1 sec to the forced vital capacity (r = 0.745 for RVEF and r = -0.718 for RV mass). CONCLUSION: Our study shows that the mean RV wall mass as measured by cardiac MDCT correlates well with the COPD disease severity as determined by PFT.

Suggestions for Radiopharmaceutical Drug Development in Korea Focusing on FDA Exploratory IND Guideline / 핵의학분자영상

Regulation for the radiopharmaceuticals should be reasonably different from that of other drugs. Radiopharmaceuticals are always used by compounding based on the doctor's order, have short half life and very low administration dose. Its pharmacological effect is not from its chemical effect but from radiation. The background for exploratory IND (Investigational New Drug) explained by the FDA was to reduce the time and resources expended on candidate products that are unlikely to suceed, new tools are needed to distinguish earlier in the process those candidates that hold promise from those that do not. In this review, basic concept for exploratory IND and RDRC guideline is summarized and various suggestions for improving and expediting procedure for new radiopharmaceutical development would be described.

Reassessment of the Usefulness of 18F-FDG PET in the Evaluation of Adrenal Masses Detected on CT or MR

PURPOSE: To reassess the usefulness of 18F-FDG PET in the differential diagnosis of benign and malignant tumors from adrenal masses detected on CT or MR. MATERIALS AND METHODS: A retrospective analysis was performed on 20 patients (n = 21), on whom PET scans were obtained with characteristically benign CT (n = 21) and MR (n = 2) findings. Seventeen patients had a proven primary malignancy and three patients had adrenal incidentalomas. PET findings were interpreted as positive if the 18F-FDG uptake of the adrenal mass was greater than or equal to that of the liver. Each adrenal mass was characterized by its size and standardized uptake value (SUV). For statistical analysis, the t-test was used to analyze results for size and SUV. RESULTS: PET findings were positive for eight adrenal masses; two masses were pathologically proven as adrenocortical oncocytomas. The false positive rate was 38% in all patients and 41% in patients with a malignancy. CONCLUSION: 18F-FDG PET was useful in evaluating the primary lesions as well as metastases, but a high false positive rate in patients with a primary malignancy should be considered in the diagnosis of metastasis to the adrenal gland.

F-18 FDG PET Scan findings in Patients with Pulmonary Involvement in the Hypereosinophilic Syndrome / 대한핵의학회잡지

PURPOSE: Hypereosinophilic syndrome (HES) is an infiltrative disease of eosinophils affecting multiple organs including the lung. F-18 2-fluoro-2-deoxyglucose (F-18 FDG) may accumulate at sites of inflammation or infection, making interpretation of whole body PET scan difficult in patients with cancer. This study was to evaluate the PET findings of HES with lung involvement and to find out differential PET features between lung malignancy and HES with lung involvement. MATERIAL AND METHODS: F-18 FDG PET and low dose chest CT scan was performed for screening of lung cancer. Eight patients who showed ground-glass attenuation (GGA) and consolidation on chest CT scan with peripheral blood eosinophilia were included in this study. The patients with history of parasite infection, allergy and collagen vascular disease were excluded. CT features and FDG PET findings were meticulously evaluated for the distribution of GGA and consolidation and nodules on CT scan and mean and maximal SUV of abnormalities depicted on F-18 FDG PET scan. In eight patients, follow-up chest CT scan and FDG PET scan were done one or two weeks after initial study. RESULTS: F-18 FDG PET scan identified metabolically active lesions in seven out of eight patients. Maximal SUV was ranged from 2.8 to 10.6 and mean SUV was ranged from 2.2 to 7.2. Remaining one patient had maximal SUV of 1.3. On follow-up FDG PET scan taken on from one to four weeks later showed decreased degree of initially noted FDG uptakes or migration of previously noted abnormal FDG uptakes. CONCLUSIONS: Lung involvement in the HES might be identified as abnormal uptake foci on FDG PET scan mimicking lung cancer. Follow-up FDG PET and CT scan for the identification of migration or resolution of abnormalities and decrement of SUV would be of help for the differentiation between lung cancer and HES with lung involvement.

Dopamine Transporter Density Assessed with 123IIPT SPECT Before and After Risperidone Treatment in Children with Tourette's Disorder / 대한핵의학회잡지

PURPOSE: Tourette's disorder (TD), which is characterized by multiple waxing and waning motor tics and one or more vocal tics, is known to be associated with abnormalities in the dopaminergic system. To testify our hypothesis that risperidone would improve tic symptoms of TD patients through the change of the dopaminergic system, we measured the dopamine transporter (DAT) densities between drug-naive children with TD and normal children, and investigated the DAT density before and after treatment with risperidone in drug-naive children with TD, using iodine-123 labelled N- (3-iodopropen-2-yl) -2beta-carbomethoxy -3beta- (4-chlorophenyl) tropane ([123I]IPT) single photon emission computed tomography (SPECT). MATERIALS AND METHODS: [123I]IPT SPECT imaging and Yale Global Tic Severity Scale-Korean version (YGTSS-K) for assessing the tic symptom severity were carried out before and after treatment with risperidone for 8 weeks in nine drug-naive children with TD. Eleven normal children also underwent SPECT imaging 2 hours after an intravenous administration of [123I]IPT. RESULTS: Drug-naive children with TD had a significantly greater increase in the specific/nonspecific DAT binding ratio of both basal ganglia compared with the normal children. However, no significant difference in the specific/nonspecific DAT binding ratio of the basal ganglia before and after treatment with risperidone in children with TD was found, although tic symptoms were significantly improved with risperidone. CONCLUSION: These findings suggest that DAT densities are directly associated with the pathophysiology of TD, however, that the effect of risperidone on tic symptoms in children with TD is not attributed to the change of dopaminergic system.

A Case of Primary Pericardial Malignant Mesothelioma / 결핵및호흡기질환

Primary pericardial malignant mesothelioma is a lethal and rare cardiac neoplasm of mesodermal origin. Most cases are associated with history of pericarditis with constriction and/or tamponade. Authors experienced a case of primary pericardial malignant mesothelioma in a 55-year old female who had suffered from dyspnea and chest pain. Pericardial nodules revealed intense uptake by FDG-PET scan and confirmed as primary pericardial malignant mesothelioma by thoracoscopic biopsy. Here we report this case with a brief review of the relevant literatures.

Effect of Homozygosity for 10-Repeat Allele at Dopamine Transporter Gene and Dopamine Transporter Density Assessed with 123IIPT SPECT on Response to Methylphenidate Treatment in Attention Deficit Hyperactivity Disorder / 신경정신의학

OBJECTIVES: The symptoms of attention-deficit/hyperactivity disorder (ADHD) can be treated with methylphenidate, a potent blocker of the dopamine transporter (DAT). The homozygosity of the 10-repeat allele at dopamine transporter gene (DAT1) seems to be associated with a poor response to methylphenidate (MPH) in children with ADHD. In present study, we investigated association between DAT density using I-123N-(3-iodopropen-2-yl)-2beta-carbomethoxy-3beta-(4-chlorophenyl)tropane ([123I]IPT SPECT) and the homozygosity for 10-repeat allele at DAT1, and response to MPH in children with ADHD. METHODS: Eleven drug-naive children with ADHD were included in the study and treated with MPH for about 8 weeks. After the genotyping and SPECT were performed, we compared DAT density between ADHD children with and without the homozygosity for the 10-repeat allele at DAT1 and investigated correlation between the homozygosity for the 10-repeat allele and response to MPH. RESULTS: ADHD children with 10/10 genotype (n=7) had a significantly higher DAT density in basal ganglia than the children without 10/10 genotype (n=4)(Right: z=-2.65, p=0.008; Left: z=-2.65, p=0.008). We found that while only 28.6% (2/7) of the subject with 10/10 genotype showed good response (> or =50% improvement) to MPH treatment, 100% (4/4) of the subjects without 10/10 genotype showed good response to MPH treatment (chi2 test: F=5.238, df=1, p=0.022). CONCLUSION: Our findings support an association between homozygosity for the 10-repeat allele at DAT1 and the DAT density assessed in vivo and correlation between the homozygosity for the 10-repeat allele and poor response to MPH.

The Role of Functional Imaging Techniques in the Dementia / 대한핵의학회잡지

Evaluation of dementia in patients with early symptoms of cognitive decline is clinically challenging, but the need for early, accurate diagnosis has become more crucial, since several medication for the treatment of mild to moderate Alzheimer' disease are available. Many neurodegenerative diseases produce significant brain function alteration even when structural imaging (CT or MRI) reveal no specific abnormalities. The role of PET and SPECT brain imaging in the initial assessment and differential diagnosis of dementia is beginning to evolve rapidly and growing evidence indicates that appropriate incorporation of PET into the clinical work-up can improve diagnostic and prognostic accuracy with respect to Alzheimer's disease, the most common cause of dementia in the geriatric population. In the fast few years, studies comparing neuropathologic examination with PET have established reliable and consistent accuracy for diagnostic evaluations using PET - accuracies substantially exceeding those of comparable studies of diagnostic value of SPECT or of both modalities assessed side by side, or of clinical evaluations done without nuclear imaging. This review deals the role of functional brain imaging techniques in the evaluation of dementias and the role of nuclear neuroimaging in the early detection and diagnosis of Alzheimer's disease.

Radiographic Manifestations of Reperfusion Edema after Transplantation

PURPOSE: To elucidate the sequential radiologic manifestations of reperfusion edema after lung transplantation. MATERIALS AND METHODS: The study group comprised five consecutive lung transplant recipients (M:F=3:2; mean age; 47.5 years) who between July 1996 and April 2002 underwent lung transplantation procedures (four, unilateral; one, bilateral) at our institution. We retrospectively reviewed the serial postoperative radiographs obtained and characterized the lung infiltrates. RESULTS: Lung infiltrates compatible with reperfusion edema were present in all patients (5/5). Reperfusion edema appeared on day 1 in four, and by day 2 in the other. In all transplanted lungs, infiltrates were found in the perihilar and basilar regions, and were scored as maximal on day 1 in one, day 3 in two, day 4 in one and day 5 in the other. CONCLUSION: The recognition of sequential radiological manifestations helps identify recognition of reperfusion edema after lung transplantation.