KSNM60 in Cardiology: Regrowth After a Long Pause.

The Korean Society of Nuclear Medicine (KSNM) is celebrating its 60th anniversary in honor of the nuclear medicine professionals who have dedicated their efforts towards research, academics, and the more comprehensive clinical applications and uses of nuclear imaging modalities. Nuclear cardiology in Korea was at its prime time in the 1990s, but its growth was interrupted by a long pause. Despite the academic and practical challenges, nuclear cardiology in Korea now meets the second leap, attributed to the growth in molecular imaging tailored for many non-coronary diseases and the genuine values of nuclear myocardial perfusion imaging. In this review, we describe the trends, achievements, challenges, and perspectives of nuclear cardiology throughout the 60-year history of the KSNM.

Comparison of perfusion 18F-FP-CIT PET and 99mTc-ECD SPECT in parkinsonian disorders.

ABSTRACT: Early and accurate identification of various conditions that can cause parkinsonian symptoms is important for determining treatment policies. Currently dopamine transporter (DAT) imaging using FP-CIT, glucose metabolism imaging using fluorodeoxyglucose, cerebral blood flow image using ethyl cysteinate dimer (ECD), and others are used for differentiation. However, the use of multiple modalities is inconvenient and costly. In the present retrospective study, we evaluated the correlation between regional brain uptake ratios (URs) in perfusion FP-CIT PET and ECD SPECT images.Twenty patients with Parkinson's symptoms underwent perfusion DAT positron emission tomography (18F-FP-CIT PET/CT) and cerebral blood flow tomography (99mTc-ECD SPECT) within a 2-week period. Perfusion 18F-FP-CIT PET/CT and 99mTc-ECD SPECT URs of 19 brain regions (bilateral frontal, temporal, parietal and occipital lobes, bilateral caudate nucleus, bilateral putamen, bilateral insula, bilateral cingulate gyrus, bilateral thalamus, and brainstem) were directly compared and correlations were analyzed.Average 18F-FP-CIT PET/CT regional perfusion URs were higher than 99mTc-ECD SPECT URs. Uptake ratios were well correlated in all 19 regions (except right putamen), and especially in dopamine poor regions (cerebral cortex). In left putamen, URs were significantly correlated, but the correlation coefficient was lower than those of other regions.A single tracer dual phase N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane test seems to be helpful for differential diagnosis of parkinsonian disorders. Large-scale, longitudinal studies on complementary diseases with parkinsonian patterns are required to investigate differences in correlations between perfusion 18F-FP-CIT PET/CT and 99mTc-ECD SPECT over time.

Potential Clinical Applications of 18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Mammography in Breast Cancer.

The whole-body positron emission tomography (PET)/magnetic resonance (MR) scan is a cutting edge technology providing comprehensive structural information from MR imaging and functional features from PET in a single session. Recent research findings and clinical experience have shown that 18F-fluorodeoxyglucose (FDG) whole-body PET/MR imaging has a diagnostic performance comparable with or superior to that of PET/CT in the field of oncology, including for breast cancer. In particular, FDG PET/MR mammography in the prone position with the breast hanging in a pendant manner can provide more comprehensive information about the metabolism, anatomy, and functional features of a breast lesion than a whole-body PET/MR scan. This article reports on current state-of-the-art PET/MR mammography in patients with breast cancer and the prospects for potential application in the future.

Comparison of the Performances of (18)F-FP-CIT Brain PET/MR and Simultaneous PET/CT: a Preliminary Study.

PURPOSE: (18)F-FP-CIT [(18)F-fluorinated N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane] has been well established and used for the differential diagnosis of atypical parkinsonian disorders. Recently, combined positron emission tomography (PET)/magnetic resonance (MR) was proposed as a viable alternative to PET/computed tomography (CT). The aim of this study was to compare the performances of conventional (18)F-FP-CIT brain PET/CT and simultaneous PET/MR by visual inspection and quantitative analysis. METHODS: Fifteen consecutive patients clinically suspected of having Parkinson's disease were recruited for the study.(18)F-FP-CIT PET was performed during PET/CT and PET/MR. PET/CT image acquisition was started 90 min after intravenous injection of (18)F-FP-CIT and then PET/MR images were acquired. Dopamine transporter (DAT) density in bilateral striatal subregions was assessed visually. Quantitative analyses were performed on bilateral striatal volumes of interest (VOIs) using average standardized uptake values (SUVmeans). Intraclass correlation coefficients (ICCs) and their 95 % confidence intervals (CIs) were assessed to compare PET/CT and PET/MR data. Bland-Altman plots were drawn to perform method-comparisons. RESULTS: All subjects showed a preferential decrease in DAT binding in the posterior putamen (PP), with relative sparing of the ventral putamen (VP). Bilateral striatal subregional binding ratio (BR) determined PET/CT and PET/MR demonstrated close interequipment correspondence (BRright caudate - ICC, 0.944; 95 % CI, 0.835-0.981, BRleft caudate - ICC, 0.917; 95 % CI, 0.753-0.972, BRright putamen - ICC, 0.976; 95 % CI, 0.929-0.992 and BRleft putamen - ICC, 0.970; 95 % CI, 0.911-0.990, respectively), and Bland-Altman plots showed interequipment agreement between the two modalities. CONCLUSIONS: It is known that MR provides more information about anatomical changes associated with brain diseases and to enable the anatomical allocations of subregions than CT, though this was not observed in the present study. Although the subregional BR of simultaneous PET/MR was comparable to that of PET/CT in Parkinson's disease, our isocontouring method could make bias. A future automated method using standard template study or manual segmentation of putamen/caudate based on MR or CT is needed.

An Incidental Finding of Skull Hemangioma During 18F-FP CIT Brain PET/CT.

F-FP CIT has been well established and used for the differential diagnosis of atypical parkinsonian disorders, including idiopathic Parkinson disease. A 54-year-old woman with a history of left hand and leg tremor underwent F-FP CIT PET/CT for the differentiation of parkinsonism. The F-FP CIT PET/CT incidentally showed focal dopamine transporter uptake in the right frontal bone. Brain MRI scan showed heterogeneous high signal intensity with enhancement in right frontal bone diploic space without cortical disruption, suggestive of cavernous hemangioma. Besides the nigrostriatal dopaminergic system, F-FP CIT PET/CT showed a skull tumor.

Clinical issues regarding misclassification by Dixon based PET/MR attenuation correction.

OBJECTIVE: The Dixon sequence is acquired for attenuation correction (AC) of positron emission tomography (PET) data in integrated PET/magnetic resonance (MR). However it sometimes misclassifies soft tissue and fat in µ-map. In the present study, we investigated factors related to this misclassification and their clinical impacts. SUBJECT AND METHODS: Forty-eight oncological patients (19 males and 29 females, mean age: 59±11 years old) underwent a single fluorine-18 fluorodeoxyglucose ((18)F-FDG) injection/dualimaging protocol on PET/computed tomography (CT) and subsequently PET/MR. Patients were assigned to either of two groups; group A with a misclassification in at least one bed position or group B with a correctly classified µ-map. We compared body mass index (BMI), lean body mass, fasting duration, volume of hydration and age between group A and group B. In addition, we analyzed the impact of PET quantification using standard uptake ratio (SUR) defined as uptake in volume of interest/uptake in thigh muscle. The Dixon-AC SUR was compared with CT-AC SUR in misclassified bed positions and correctly classified bed positions. All patients were scanned in four bed positions by PET/MR. Ten patients were assigned to group A; six showed misclassification in a bed position (5 in head and 1 in abdomen), three patients in 3 bed positions (head-thorax-abdomen), and one patient in partial bed position in neck. RESULTS: Misclassification was observed in 21% of 48 patients. Group A and group B showed no statistically significant differences in BMI, lean body mass, fasting duration or age, however the volume of hydration in group A (245mL) was smaller than in group B (452.6mL) (P=0.027). In group A, we analyzed Dixon-AC SUR/CT-AC SUR ratios in 16 misclassified and 24 correctly classified regions, and ratios in these regions were significant different 0.80 and 0.93, respectively (P=0.046). CONCLUSION: Because no corrective method has been devised after a scan, we recommend that Dixon images with µ-maps should be checked before interpreting PET/MR images and emphasize the importance of hydration, pre-examination. Misclassification errors do not change the presence of (18)F-FDG uptake but can have significant impacts on PET quantification in affected bed positions.

Initial experience of integrated PET/MR mammography in patients with invasive ductal carcinoma.

The purpose of this study was to evaluate the feasibility of integrated fluorine-18-fluorodeoxyglucose positron emission tomography/magnetic resonance ((18)F-FDG PET/MR) mammography in invasive ductal carcinoma (IDC) patients. From August 2012 to March 2013, we enrolled 42 consecutive breast cancer patients who received whole- body PET/MR and subsequent PET/MR mammography by an integrated PET/MR scanner and were scheduled for surgery within 2 weeks after the of scan. On the whole body PET/MR, 2-point Dixon VIBE, coronal T1w image, axial T2w image, and post-contrast T1 sequences were acquired with simultaneous PET acquisition. For PET/MR mammography, T1w, T2w, and dynamic contrast-enhancement (DCE) sequences were acquired using a breast coil during simultaneous PET acquisition. We compared the detectability of the lesions between whole-body PET/MR and PET/MR mammography. Forty-eight IDC (1.89±1.19cm of width) were diagnosed in 42 women. Lesion conspicuity in (18)F-FDG PET was equivalent between whole-body PET/MR and PET/MR mammography; both PET/MR images showed 38 hypermetabolic masses. In the analysis of 10 IDC with <1.0cm wide lesions, only 1 IDC showed (18)F-FDG uptake, and 4 IDC were noted on whole-body PET/MR; however, all 10 IDC showed a depictable mass on PET/MR mammography. In the analysis of 38 IDC >1.0cm wide, 37 IDC showed (18)F-FDG uptake, and 38 IDC were detected on both whole-body PET/MR and PET/MR mammography. The overall sensitivity was 79.2% (38/48) on PET, 87.5% (42/48) on whole-body PET/MR, and 100% on PET/MR mammography. The SUV between whole-body PET/MR and PET/MR mammography showed strong and highly significant correlation (r=0.987, P<0.001). In conclusion, our results, although in a limited number of cases show that integrated PET/MR mammography is feasible and has the advantage of combining high-resolution breast images with metabolic images. Furthermore, PET/MR mammography could provide an accurate diagnosis in case of IDC that are less than 1cm in size.

Prevalence of extracardiac findings in the evaluation of ischemic heart disease by multidetector computed tomography.

OBJECTIVE: Multidector computed tomography (MDCT) is now commonly used for the evaluation of coronary artery disease. Because MDCT images include many non-cardiac organs and the patient population evaluated is highly susceptible to extracardiac diseases, this study was designed to evaluate the prevalence of extracardiac findings in the MDCT evaluation of ischemic heart disease. METHODS: From March 2007 to March 2008, a total of six-hundred twenty patients, who underwent 64-slice MDCT evaluations for chest pain, or dyspnea, were enrolled in this study. Cardiac and non-cardiac findings were comprehensively evaluated by a radiologist. RESULTS: Enrolled patients included 306 men (49.4%), with a mean age of 66 years. Significant coronary artery stenosis was found in 41.6% of the patients. A total of 158 extracardiac findings were observed in 110 (17.7%) patients. Commonly involved extracardiac organs were lung (36.7%), hepatobiliary system (21.5%), thyroid (19.6%), kidney (10.8%), spine (9.7%) and breast (0.6%). Of those 110 patients, 50 (45.5%) patients underwent further diagnostic investigations. Malignant disease was detected in three (2.7%) patients (lung cancer, pancreatic cancer, and thyroid cancer). CONCLUSIONS: Extracardiac findings are frequently present and should be a concern in the MDCT evaluation of chest pain syndrome.

Diagnostic Accuracy of 64-Slice MDCT Coronary Angiography for the Assessment of Coronary Artery Disease in Korean Patients with Type 2 Diabetes.

BACKGROUND: A 64-slice multidetector computed tomography (MDCT) is well known to be a useful noninvasive form of angiography for the general population, but not for certain patients with diabetes. The aim of this study was to investigate the diagnostic accuracy and usefulness of 64-slice MDCT coronary angiography for detecting coronary artery disease in Korean patients with type 2 diabetes mellitus (T2DM). METHODS: A total of 240 patients were included, 74 of whom had type 2 diabetes (M:F=40:33; 41.8±9.5 years). We compared significant coronary stenosis (>50% luminal narrowing) in MDCT with invasive coronary angiography (ICA) by segment, artery, and patient. We also evaluated the influence of obesity and coronary calcium score on MDCT accuracy. RESULTS: Of the 4,064 coronary segments studied, 4,062 segments (T2DM=1,109) were assessed quantitatively by both MDCT and ICA, and 706 segments (T2DM=226) were detected as a significant lesion by ICA in all patients. Sensitivity, specificity, as well as positive and negative predictive values for the presence of significant stenosis in T2DM were: by segment, 89.4%, 96.4%, 85.8%, and 97.4%, respectively; by artery (n=222), 95.1%, 92.9%, 94.4%, and 93.8%, respectively; by patients (n=74), 98.4%, 100.0%, 98.4%, and 90.0%, respectively. Regardless of presence of diabetes, there was no significant difference in diagnostic accuracy. Obesity (≥25 kg/m(2)) and coronary calcium score did not also affect the diagnostic accuracy of MDCT. CONCLUSION: The 64-slice MDCT coronary angiography was found to have similar diagnostic accuracy with ICA, regardless of diabetes. These results suggest MDCT may be helpful to reduce unnecessary invasive studies for patients with diabetes.

Brain SPECT Analysis After Constraint-Induced Movement Therapy in Young Children with Hemiplegic Cerebral Palsy: Case Report.

Constraint-induced movement therapy (CIMT) was shown recently to be promising for improving upper-limb function in children with cerebral palsy (CP). This study investigated the changes in cerebral perfusion with single-photon emission computerized tomography (SPECT) after modified CIMT (child-friendly CIMT) in young hemiplegic girls. Two young children with left hemiplegic CP were studied with SPECT at rest before and after the CIMT period, and they also performed standardized upper motor function tests [Jebsen hand function test, quality of upper extremity skills test (QUEST), and dynamic electromyography (EMG)]. The cerebral perfusion SPECT revealed regional perfusion increase in the motor cortex area in the affected hemisphere, and the changes associated with functional gain. Our cases showed that intensive movement therapy appears to change local cerebral perfusion and SPECT could show these changes in children with hemiplegic CP.

Myocardial Fibrosis in Hypertrophic Cardiomyopathy Demonstrated by Integrated Cardiac F-18 FDG PET/MR.

Hypertrophic cardiomyopathy (HCM) is a common condition defined as a diffuse or segmental left ventricular (LV) hypertrophy with a nondilated and hyperdynamic chamber as well as cardiac arrhythmias. Cardiac MR (CMR) imaging is a key modality for evaluation of HCM. In addition to the assessment of LV wall thickness, LV function and aortic flow, CMR is capable of estimation of late gadolinium enhancement (LGE) in affected myocardium which has been shown to have a direct correlation with incidence and severity of arrhythmias in HCM. In patients with HCM, LGE on CMR is presumed to represent intramyocardial fibrosis. Meanwhile, F-18 FDG myocardial PET has been sporadically studied in HCM, mostly for evaluation of the metabolic status of a hypertrophic myocardial segment, especially after interventions or to demonstrate partial myocardial fibrosis. We presented here the case of a 25-year-old male patient referred for simultaneous F-18 FDG cardiac PET/MR for the evaluation of septal hypertrophy. The PET/MR revealed myocardial fibrosis in the septum associated with FDG-defect and LGE.

The Impact of Energy Substrates, Hormone Level and Subject-Related Factors on Physiologic Myocardial (18)F-FDG Uptake in Normal Humans.

PURPOSE: In a whole-body (18)F-FDG PET/CT, non-specific (18)F-FDG uptake of the myocardium is a common finding and can be very variable, ranging from background activity to intense accumulation and inhomogeneity. We investigated the effect of energy substrates and plasma/serum hormones that may have an influence on myocardial (18)F-FDG uptake. METHODS: F-FDG PET/CT was performed on 100 normal volunteers from November 2007 to August 2008. Blood samples were taken just before (18)F-FDG injection from all subjects. Myocardial (18)F-FDG uptake was measured as the mean (SUVmean) and maximal (SUVmax) standardized uptake value. The myocardium was delineated on the PET/CT image by a manual volume of interest (VOI). We analyzed the influence of age, sex, presence of diabetes, fasting duration, insulin, glucagon, fasting glucose, lactate, free fatty acid (FFA), epinephrine (EPi), norepinephrine (NEp), free triiodothyronine (T3), free thyroxine (T4), thyroid-stimulating hormone (TSH) and body mass index (BMI). RESULTS: Overall, 92 subjects (mean age 50.28 ± 8.30, male 57) were enrolled. The average of myocardial SUVmean was 2.08 and of myocardial SUVmax was 4.57, respectively and there was a strong linear correlation between SUVmean and SUVmax (r = 0.98). FFA and fasting duration showed significant negative correlation with myocardial (18)F-FDG uptake, respectively (r = -0.40 in FFA; r = -0.41 in fasting duration). No significant relationships were observed between myocardial uptake and age, sex, presence of diabetics, insulin, glucagon, fasting glucose, lactate, EPi, NEp, free T3, free T4, TSH and BMI. CONCLUSION: Myocardial (18)F-FDG uptake decreases with longer fasting duration and higher FFA level in normal humans. Modulating myocardial uptake could improve (18)F-FDG PET/CT imaging for specific oncologic and cardiovascular indications.

Clinical usefulness of combinatorial protocol with stress only myocardial perfusion SPECT, CTA and SPECT/CTA 3-dimensional fusion image.

BACKGROUND: This study was designed to assess the value of a combinatorial protocol, namely, stress only myocardial perfusion SPECT (MPS), 64-slice coronary computed tomographic angiography (CTA), and SPECT/CTA 3-dimensional (3D) fusion imaging for the evaluation of coronary artery disease. METHODS: A total of 142 patients were retrospectively reviewed. All underwent stress only MPS and 64-slice CTA before invasive coronary angiography (ICA). The SPECT/CTA 3D fusion images were generated. We compared the results of the combinatorial protocol with ICA. RESULTS: Seventy nine (76.0%) subjects were found to have ≥50% stenoses, by ICA. The sensitivity of the combinatorial examination was 100% and its specificity 80.8%. Its positive and negative predictive values were 94.0 and 100%, respectively. The number of lesion for abnormal MPS with matching significant stenoses on CTA is 94 [43 in left anterior descending (LAD); 19 in left circumflex (LCX); 32 in right coronary artery (RCA)], the number of lesion for equivocal perfusion defect with matching stenoses on CTA is 24 (14 in LAD; 7 in LCX; 3 in RCA). The number of coronary arterial stenoses without MPS abnormality is 10, 4 stenoses were detected in left main lesion and the other stenoses were comparatively mild lesion in multi-vessel disease. CONCLUSION: Stress only MPS/CTA 3D fusion imaging could provide the potential for improved diagnostic accuracy and additional information of hemodynamically relevant coronary arterial stenoses.

(18)F-FDG PET/CT in inflammatory pseudotumor of the colon causing intussusception.

Inflammatory pseudotumor is a rare benign lesion mimicking malignancy both clinically and radiologically. An accurate diagnosis is still difficult and is based on the histological examination. Since inflammatory pseudotumor is exceptionally rare in the colon, this unexpected lesion can be mistaken for malignancy. We report the first case of inflammatory pseudotumor in the colon that showed (18)F-fluorodeoxyglucose (FDG) uptake and acted as the lead point causing colocolic intussusception.

Stent fracture and restenosis after zotarolimus-eluting stent implantation.

Stent fracture (SF) has been found in peripheral and coronary vasculatures, and in the latter mostly after implantation of sirolimus- or paclitaxel-eluting stents. We report a patient with a fractured stent associated with restenosis after zotarolimus-eluting stent (ZES) implantation which was confirmed by fluoroscopy, intravascular ultrasound and computerized tomography. To our knowledge, this is the first published report of SF after ZES implantation.

Non-Specific Disease Mimicking Malignancy: Two Cases of FDG Uptake in the Extremities.

FDG PET is an imaging technique used to assess regional differences in glucose metabolism. A variety of diseases, including malignancy, can show abnormal FDG uptake in bone marrow. PET/CT demonstrated non-specific uptake in the extremities of two patients with fever of unknown origin (FUO). Both patients showed focal and symmetric FDG uptake in the bone marrow of the arms and legs. Although the results of these cases were not diagnostic, the unique uptake pattern of PET/CT should be considered a non-specific reactive change as well as malignancy or other possibilities in the initial differential diagnosis.

Acute myocardial infarction as a consequence of stent fracture and plaque rupture after sirolimus-eluting stent implantation.

Stent fracture (SF) is emerging as one of the leading causes of late cardiac events after sirolimus-eluting stent (SES) implantation. A 44-year old man was admitted with ST-segment elevated myocardial infarction 22 months after treatment with SES. SF was confirmed by fluoroscopy, intravascular ultrasound study (IVUS) and computerized tomographic study. IVUS demonstrated a soft, ruptured plaque at the site of the SF where the plaque was not covered by the stent strut. This case suggests that rupture of vulnerable plaque because of SF led to thrombosis and acute myocardial infarction.