• The Korean Journal of Nuclear Medicine Technology
• /
• v.21 no.2
• /
• pp.31-36
• /
• 2017

Purpose Recently, the performance of PET/CT scanner has been improved and various techniques have been developed to increase the image quality such as Sensitivity and Resolution. The purpose of this study is to evaluate the usefulness of Q.Clear (a fully convergent iterative reconstruction) technique of GE Discovery IQ equipment to enhance the image quality. Materials and Methods All scans were acquired by Discovery IQ (GE Healthcare, MI, USA). In NEMA IEC Body Phantom test, Background to Hot-sphere (10 mm, 13 mm, 17 mm, 22 mm) ratio was 1:4 and scan time was 3 minutes. The images were reconstructed by VPHDs (VUE Point High-Definition + SharpIR) and Q.Clear to evaluate each Contrast. We injected 18F-FDG 187 M㏃ to PET/SPECT Performance Phantom. And then it was scanned for 4 minutes to evaluate Resolution and Uniformity. T-test statistical analysis was performed on SUVmax of small lesions less than 2 cm in 100 clinical patients regardless of disease type. Results In the NEMA IEC Body Phantom, the Contrast was $63.6{\pm}5.7%$ (VPHDs) and $75{\pm}4.8%$ (Q.Clear). In the PET/SPECT Performance Phantom, the Resolution was 9.2 mm (VPHDs) and 7.3 mm (Q.Clear). Uniformity of Q.Clear was 10.8% better than VPHDs. T-test statistic of the clinical patients showed a significant difference of p value of 0.021. Conclusion Both the phantom test and the clinical results showed that the quality of the image was improved in Q.Clear was applied. The SUVmax was highly measured in Q.Clear and the lesions were clearly distinguished visually. Therefore Q.Clear can be useful in various aspects such as dose-reduction, patients evaluation and image analysis.

• The Korean Journal of Nuclear Medicine
• /
• v.34 no.6
• /
• pp.478-486
• /
• 2000

Purpose: The sentinel lymph node is defined as the first draining node from a primary tumor and reflects the histologic feature of the remainder of the lymphatic basin status. The aim of this study was to evaluate the usefulness of lymphoscintigraphy and intraoperative radioguided gamma probe for identification and removal of sentinel lymph node in breast cancer. Materials and Methods: Lymphoscintigraphy was performed preoperatively in 15 patients with biopsy proven primary breast cancer. Tc-99m antimony sulfide colloid was injected intradermally at four points around the tumor. Imaging acquisition included dynamic imaging, followed by early and late static images at 2 hours. The sentinel lymph node criteria on lymphoscintigraphy is the first node of the highest uptake in early and late static images. We tagged the node emitting the highest activity both in vivo and ex vivo. Histologic study for sentinel and axillary lymph node investigation was done by Hematoxylin-Eosin staining. Results: On lymphoscintigraphy, three of 15 patients had clear lymphatic vessels in dynamic images, and 11 of 15 patients showed sentinel lymph node in early static image and three in late static 2 hours image. Mean detection time of sentinel lymph node on lymphoscintigraphy was $33.5{\pm}48.4$ minutes. The sentinel lymph node localization and removal by lymphoscintigraphy and intraoperative gamma probe were successful in 14 of 15 patients (detection rate: 93.3%). On lymphoscintigraphy, 14 of 15 patients showed $2.47{\pm}2.00$ sentinel lymph nodes. On intraoperative gamma probe, $2.36{\pm}1.96$ sentinel lymph nodes were detected. In 7 patients with positive results of sentinel lymph node metastasis, 5 patients showed positive results of axillary lymph node (sensitivity: 72%) but two did not. In 7 patients with negative results of sentinel lymph node metastasis, all axillary nodes were free of disease (specificity: 100%). Conclusion: Sentinel lymph node biopsy with lymphoscintigraphy and intraoperative gamma probe is a reliable method to predict axillary lymph node metastasis in breast cancer, and unnecessary axillary lymph node dissection can be avoided.

• The Korean Journal of Nuclear Medicine
• /
• v.32 no.4
• /
• pp.332-343
• /
• 1998

Purpose: The purpose of this study was to assess the diagnostic accuracy of various quantitation methods using F-18-fluorodeoxyglucose (FDG) in patients with malignant or benign lung lesion. Materials and Methods: 22 patients (13 malignant including 5 bronchoalverolar cell cancer; 9 benign lesions including 1 hamartoma and 8 active inflammation) were studied after overnight fasting. We performed dynamic PET imaging for 56 min after injection of 370 MBq (10 mCi) of FDG. Standardized uptake values normalized to patient's body weight and plasma glucose concentration (SUVglu) were calculated. The uptake rate constant of FDG and glucose metabolic rate were quantified using Patlak graphical analysis (Kpat and MRpat), three compartment-five parameter model (K5p, MR5p), and six parameter model taking into account heterogeneity of tumor tissue (K6p, MR6p). Areas under receiver operating characteristic curves (ROC) were calculated for each method. Results: There was no significant difference of rate constant or glucose metabolic rate measured by various quantitation methods between malignant and benign lesions. The area under ROC curve were 0.73 for SUVglu, 0.66 for Kpat, 0.77 for MRpat, 0.71 for K5p, 0.73 for MR5p, 0.70 for K6p, and 0.78 for MR6p. No significant difference of area under the ROC curve between these methods was observed except the area between Kpat vs. MRpat (p<0.05). Conclusion: Quantitative methods did not improve diagnostic accuracy in comparison with nonkinetic methods. However, the clinical utility of these methods needs to be evaluated further in patients with low pretest likelihood of active inflammation or bronchoalveolar cell carcinoma.

• The Korean Journal of Nuclear Medicine
• /
• v.29 no.1
• /
• pp.41-47
• /
• 1995

Tc-99m-MIBI(Sestamibi) myocardial SPECT along with T1-201 tomographic imaging has demonstrated wide application and high image qualify sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow, The qualitative values of myocardial SPECT with Tc-99m-MIBI as well as the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection(FBP) is the common standard for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it Is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected filter parameters such as cutoff frequencies and order(Butterworth case). The cutoff frequencies basically remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable thresh-old of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Nyquist frequency would reveal severe degradation of radio-active distribution near inferior and/or Inferoseptal myocardium when applying Butterworth or low pass filter.

• The Korean Journal of Nuclear Medicine
• /
• v.28 no.1
• /
• pp.44-51
• /
• 1994

It is known that the normal His-Purkinje system provides for nearly synchronous activation of right (RV) and left (LV) ventricles. When His-Purkinje conduction is abnormal, the resulting sequence of ventricular contraction must be correspondingly abnormal. These abnormal mechanical consequences were difficult to demonstrate because of the complexity and the rapidity of it's events. To determine the relationship of the phase changes and the abnormalities of ventricular conduction, we performed phase image analysis of $^{99m}Tc$-RBC gated blood pool scintigrams in patients with intraventricular conduction disturbances (24 complete left bundle branch block (C-LBBB), 15 complete right bundle branch block (C-RBBB), 13 Wolff-Parkinson-White syndrome (WPW), 10 controls). The results were as follows; 1) The ejection fraction (EF), peak ejection rate (PER), and peak filling rate (PFR) of LV in gated blood pool scintigraphy (GBPS) were significantly lower in patients with C-LBBB than in controls ($44.4{\pm}13.9%$ vs $69.9{\pm}4.2%,\;2.48{\pm}0.98$ vs $3.51{\pm}0.62,\;1.76{\pm}0.71$ vs $3.38{\pm}0.92$, respectively, p<0.05). 2) In the phase angle analysis of LV, Standard deviation (SD), width of half maximum of phase angle (FWHM), and range of phase angle were significantly increased in patients with C-LBBB than in controls ($20.6{\pm}18.1$ vs $8.6{\pm}1.8,\;22.5{\pm}9.2$ vs $16.0{\pm}3.9,\;95.7{\pm}31.7$ vs $51.3{\pm}5.4$, respectively, p<0.05). 3) There was no significant difference in EF, PER, PFR between patients with the Wolff-parkinson-White syndrome and controls. 4) Standard deviation and range of phase angle were significantly higher in patients with WPW syndrome than in controls ($10.6{\pm}2.6$ vs $8.6{\pm}1.8$, p<0.05, $69.8{\pm}11.7$ vs $51.3{\pm}5.4$, p<0.001, respectively), however, there was no difference between the two groups in full width of half maximum. 5) Phase image analysis revealed relatively uniform phase across the both ventricles in patients with normal conduction, but markedly delayed phase in the left ventricle of patients with LBBB. 6) In 13 cases of WPW syndrome, the site of preexcitation could be localized in 10 cases (77%) by phase image analysis. Therefore, it can be concluded that phase image analysis can provide an accurate noninvasive method to detect the mechanical consequences of a wide variety of abnormal electrical activation in ventricles.

• The Korean Journal of Nuclear Medicine
• /
• v.28 no.1
• /
• pp.75-84
• /
• 1994

The need for assessment of ureteric function in the patient with an obviousely dilated ureter has increased particularly with the added spectrum of asymptomatic patients presenting with hydrone-phrosis and hydroureter on antenatal and perinatal ultrasound. To assess the influence of ureteral status on kidney washout during $^{99m}Tc$-DTPA diuretic renography, ureteral images were reviewed in 80 children referred for hydronephrosis. A scintigraphically abnormal ureter was defined as an intense and continuous image of > 10 min during diuretic renography. Out of them, a total of 16 nephroureteral systems in 12 children with scintigraphically abnormal ureter were analyzed. A diuretic washout index using response half time (t1/2) by linear fitting after lasix injection, was determined on renal (Kt1/2) and ureteral (Ut1/2) curves (diuretic renogram vs. diuretic ureterogram). Diuretic ureterogram curve patterns corresponding to normal (type I), obstructive (II) and non-obstructive (III) cases were described. Compared with X-ray data, diuretic renography was highly sensitive (88%) and specific (99%) for detecting any ureteral abnormality. Despite an obstructive Kt1/2 (>20 min), no patient with an abnormal ureter underwent therapy at the ureteropelvic junction because the hydronephrosis regressed after surgery at the lower level. Our data indicate that the abnormal ureter findings during diuretic renography have to be recognized before therapy for children with hydeonephrosis.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.18 no.1
• /
• pp.127-133
• /
• 2014

Purpose: Low dose of PET/CT is important because of Patient's X-ray exposure. The aim of this study was to evaluate the effectiveness of low-dose PET/ CT image through the CTAC and QAC of patient study and phantom study. Materials and Methods: We used the discovery 710 PET/CT (GE). We used the NEMA IEC body phantom for evaluating the PET data corrected by ultra-low dose CT attenuation correction method and NU2-94 phantom for uniformity. After injection of 70.78 MBq and 22.2 MBq of 18 F-FDG were done to each of phantom, PET/CT scans were obtained. PET data were reconstructed by using of CTAC of which dose was for the diagnosis CT and Q. AC of which was only for attenuation correction. Quantitative analysis was performed by use of horizontal profile and vertical profile. Reference data which were corrected by CTAC were compared to PET data which was corrected by the ultra-low dose. The relative error was assessed. Patients with over weighted and normal weight also underwent a PET/CT scans according to low dose protocol and standard dose protocol. Relative error and signal to noise ratio of SUV were analyzed. Results: In the results of phantom test, phantom PET data were corrected by CTAC and Q.AC and they were compared each other. The relative error of Q.AC profile was been calculated, and it was shown in graph. In patient studies, PET data for overweight patient and normal weight patient were reconstructed by CTAC and Q.AC under routine dose and ultra-low dose. When routine dose was used, the relative error was small. When high dose was used, the result of overweight patient was effectively corrected by Q.AC. Conclusion: In phantom study, CTAC method with 80 kVp and 10 mA was resulted in bead hardening artifact. PET data corrected by ultra- low dose CTAC was not quantified, but those by the same dose were quantified properly. In patients' cases, PET data of over weighted patient could be quantified by Q.AC method. Its relative difference was not significant. Q.AC method was proper attenuation correction method when ultra-low dose was used. As a result, it is expected that Q.AC is a good method in order to reduce patient's exposure dose.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.3
• /
• pp.215-223
• /
• 2013

Purpose : To evaluate the effect of gadoxetic acid on the measurement of the stiffness value of MR elastography (MRE) used to evaluate hepatic fibrosis (HF). Materials and Methods: MRE was obtained in 32 patients with clinically suspected chronic liver disease, both before and after injection of gadoxetic acid. Two independent reviewers measured the stiffness values of the liver parenchyma on elastograms. The mean liver stiffness values were compared in the pre- and post-contrast MREs using the paired t-test. Intra-rater and inter-rater correlation was assessed using the intraclass correlation coefficient (ICC). The accuracy, sensitivity, and specificity of both pre- and post-contrast MREs was evaluated for the diagnosis of significant HF (${\geq}F2$) using cut off value of 3.1 kPa. Results: There were no significant differences in the stiffness values of the liver parenchyma on pre- and post-contrast MREs (p = 0.15 and 0.38 for each reader, respectively). Regarding intra-rater correlation, excellent agreement was noted on rater 1(ICC = 0.998) and rater 2 (ICC = 0.996). Excellent correlation regarding the measured stiffness values was noted on both pre- and post-contrast MREs (ICC = 0.988 for pre-contrast, ICC = 0.993 for post-contrast). The accuracy, sensitivity, and specificity of the pre- and post-contrast MREs for differentiating significant HF (${\geq}F2$) from ${\geq}F1$ were same as 71%, 60%, and 100%, respectively. Conclusion: As there was no significant difference in the stiffness measurements seen on MREs before and after administration of gadoxetic acids, it is therefore acceptable to perform MRE after contrast injection in order to evaluate HF.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.3
• /
• pp.232-238
• /
• 2013

Purpose : We investigated the possible added value of magnetic resonance imaging (MR) in staging of malignant pleural mesothelioma (MPM) compared to computed tomography (CT). Materials and Methods: We retrospectively enrolled 20 patients (M;F = 14:6; mean age, 53.5 yrs) who diagnosed as MPM by histology and underwent CT and MR at initial evaluation from Jan 1997 to Dec 2012. Two radiologists performed clinical staging by using CT alone or MR alone in consensus. In patients underwent surgery (n = 13), we evaluated the diagnostic accuracy of CT and MR in terms of staging compared to surgical staging. In all patients, we compared clinical staging of CT only and CT with MR. Results: The diagnostic accuracy for T staging of CT only was 23.1% (3/13) and that of combined CT and MR was 38.5% (5/13), respectively. Among 13 patients underwent surgery, surgical stage was higher than combined CT and MR stage in 5 patients, but lower in 3 patients. CT only and combined CT and MR agreed in 85.0% (17/ 20). In cases of disagree (15.0%, 3/20), combined CT and MR showed higher stage than CT only. Conclusion: Combined CT and MR increases the diagnostic accuracy in staging of MPM compared to CT only and is important in determining the appropriate treatment in patients being considered for surgery.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.23 no.1
• /
• pp.29-34
• /
• 2019

Purpose An examination guide is a useful medium to provide the patient with an overview, pre- and post-test preparation, and precautions of nuclear testing. The design and arrangement of existing written texts and announcements were evaluated to elucidate the comprehension of patients undergoing testing. Materials and Methods Informational material describing bone scanning and $^{201}thallium$ myocardium perfusion single-photon emission computed tomography (SPECT), as a secondary examination, which accounts for the largest portion of gamma imaging at Asan Hospital (Seoul, South Korea), was selected as an improvement target in consultation with a national innovation center. Existing informational material was dispensed to patients scheduled for bone scans from November 2016 to February 2017 and the revised material was issued from March 2017 to May 2017. A survey was conducted of 200 patients who underwent $^{201}thallium$ myocardium perfusion SPECT before and after the revisions (n = 100 each time period) to assess the patients' understanding of the informational material. Results When comparing the use of the conventional vs. revised material, the number of patients who received treatment before bone scanning had decreased from 130 to 60, while the number of those who required additional imaging decreased from 53 to 14. Prior to the revision, 43% of patients underwent testing before preparation and 18% underwent additional testing. The decreased need for additional image acquisition after revision of the informational material resulted in a decrease in acquisition time of about 2 min, from 16.5 to 14.2 min. In the case of $^{201}thallium$ myocardium perfusion SPECT, patient comprehension of all five items surveyed had increased, while the number of patients who had repeatedly asked about various facets of the procedure pre- and post-testing had decreased from 36% to 16% and 31% to 14%, respectively. Conclusion Lower patient comprehension is accompanied by a decrease in image quality due to non-compliance during pre-testing and may lead to repetitive questions from the patient, which may also negatively affect the fatigue and work efficiency of the examiner. Improved readability and visibility of informational material through visualization was correlated with greater patient comprehension as well as improved image quality and acquisition time.