Follicular Lymphoma mimicking Metastatic Nodes on the F-18 FDG PET/CT and MRI for Staging of Endometrial Cancer / 대한핵의학회잡지

A 53-year-old woman was diagnosed with endometrial carcinoma by vaginal bleeding. F-18 fluorodeoxy glucose positron emission tomography PET/CT (F-18 FDG PET/CT) scan for staging showed intense focal FDG uptake in the endometrium suggesting endometrial malignancy. PET/CT showed multiple node uptakes in the pericaval region, paraaortic region, common iliac, and both internal iliac and external iliac regions suggesting multiple pelvic and retroperitoneal node metastases. MRI showed multiple metastatic lymphadenopathy in the retroperitoneum and pelvic cavity. Pathologic diagnosis performed with dissected pelvic and paraaortic nodes was confirmed as a follicular malignant lymphoma positive for B-cell lymphoma-2(Bcl-2) stain, not the metastatic node of primary endometrioid carcinoma.

Follicular Lymphoma mimicking Metastatic Nodes on the F-18 FDG PET/CT and MRI for Staging of Endometrial Cancer / 대한핵의학회잡지

A 53-year-old woman was diagnosed with endometrial carcinoma by vaginal bleeding. F-18 fluorodeoxy glucose positron emission tomography PET/CT (F-18 FDG PET/CT) scan for staging showed intense focal FDG uptake in the endometrium suggesting endometrial malignancy. PET/CT showed multiple node uptakes in the pericaval region, paraaortic region, common iliac, and both internal iliac and external iliac regions suggesting multiple pelvic and retroperitoneal node metastases. MRI showed multiple metastatic lymphadenopathy in the retroperitoneum and pelvic cavity. Pathologic diagnosis performed with dissected pelvic and paraaortic nodes was confirmed as a follicular malignant lymphoma positive for B-cell lymphoma-2(Bcl-2) stain, not the metastatic node of primary endometrioid carcinoma.

Ipsilateral Cerebral and Contralateral Cerebellar Hyperperfusion in Patients with Unilateral Cerebral Infarction; SPM Analysis / 핵의학분자영상

PURPOSE: Cortical reorganization has an important role in the recovery of stroke. We analyzed the compensatory cerebral and cerebellar perfusion change in patients with unilateral cerebral infarction using statistical parametric mapping (SPM). MATERIALS AND METHODS: Fifty seven (99m)Tc-Ethylene Cystein Diethylester (ECD) cerebral perfusion SPECT images of 57 patients (male/female=38/19, mean age=56+/-17 years) with unilateral cerebral infarction were evaluated retrospectively. Patients were divided into subgroups according to the location (left, right) and the onset (acute, chronic) of infarction. Each subgroup was compared with normal controls (male/female=11/1, mean age=36+/-10 years) in a voxel-by-voxel manner (two sample t-test, p<0.001) using SPM. RESULTS: All 4 subgroups showed hyperperfusion in the ipsilateral cerebral cortex, but not in the contralateral cerebral cortex. Chronic left and right infarction groups revealed hyperperfusion in the ipsilateral primary sensorimotor cortex, meanwhile, acute subgroups did not. Contralateral cerebellar hyperperfusion was also demonstrated in the chronic left infarction group. CONCLUSION: Using (99m)Tc-ECD SPECT, we observed ipsilateral cerebral and contralateral cerebeller hyperperfusion in patients with cerebral infarction. However, whether these findings are related to the recovery of cerebral functions should be further evaluated.

Development of Decision Tree Software and Protein Profiling using Surface Enhanced Laser Desorption/Ionization - Time of Flight - Mass Spectrometry (SELDI-TOF-MS) in Papillary Thyroid Cancer / 핵의학분자영상

PURPOSE: The aim of this study was to develop a bioinformatics software and to test it in serum samples of papillary thyroid cancer using mass spectrometry (SELDI-TOF-MS). MATERIALS AND METHODS: Development of 'Protein analysis' software performing decision tree analysis was done by customizing C4.5. Sixty-one serum samples from 27 papillary thyroid cancer, 17 autoimmune thyroiditis, 17 controls were applied to 2 types of protein chips, CM10 (weak cation exchange) and IMAC3 (metal binding - Cu). Mass spectrometry was performed to reveal the protein expression profiles. Decision trees were generated using 'Protein analysis' software, and automatically detected biomarker candidates. Validation analysis was performed for CM10 chip by random sampling. RESULTS: Decision tree software, which can perform training and validation from profiling data, was developed. For CM10 and IMAC3 chips, 23 of 113 and 8 of 41 protein peaks were significantly different among 3 groups (p<0.05), respectively. Decision tree correctly classified 3 groups with an error rate of 3.3% for CM10 and 2.0% for IMAC3, and 4 and 7 biomarker candidates were detected respectively. In 2 group comparisons, all cancer samples were correctly discriminated from non-cancer samples (error rate = 0%) for CM10 by single node and for IMAC3 by multiple nodes. Validation results from 5 test sets revealed SELDI-TOF-MS and decision tree correctly differentiated cancers from non-cancers (54/55, 98%), while predictability was moderate in 3 group classification (36/55, 65%). CONCLUSION: Our in-house software was able to successfully build decision trees and detect biomarker candidates, therefore it could be useful for biomarker discovery and clinical follow up of papillary thyroid cancer.

Fractional Creatinine Clearance of the Donated Kidney As a Predictor of Graft Function after Living Donor Transplantation / 대한이식학회지

PURPOSE: An insufficient functioning nephron mass might fail to meet the metabolic demands of the recipient and lead to hyperfiltration. This hyperfiltration damage also increase allograft failure rates. During the preoperative evaluation of a potential kidney donor, it is important to estimate the renal function of donated kidney compared with the metabolic needs of the recipient. METHODS: The functional ratio of each kidney was measured using technetium-99m diethylenetriaminepentaacetic acid. The serum creatinine (Scr, mg/dL) and estimated creatinine clearance (Ccr, mL/min/1.73m2) using the Cockcroft-Gault formula were measured and calculated in 82 donors. We excluded recipients who had an episode of rejection, and followed all recipients for more than 12 months posttransplantation. RESULTS: The average functional proportion of the donated kidney was 50.5%+/-4.7% of the total Ccr 83.4+/-18.3 of donors. The Scr of recipients at 1,3,6 and 9months posttransplantation were significantly (P<.05) correlated with the fractional Ccr of thedonated kidney; however Scr at 1 year was not correlated (P=.307). Furth-ermore the Ccr of the recipient at 1, 3, and 6months post transplantation were significantly (P<.05) correlated with fractional Ccr ofthe donated kidney; however the Ccr at 9months and 1 year were not correlated (P=.094 and.141, respectively). CONCLUSION: The Scr and Ccr of recipients within 6 months after transplantation may depend on the functional mass of the donated kidney, which should be estimated prior to kidney donation and compared with the metabolic demands of the potential recipient.

Usefulness of Uptake Ratio of Three Phase Bone Scintigraphy in Complex Regional Pain Syndrome after a Stroke

OBJECTIVE: To evaluate usefulness of uptake ratio of three phase bone scintigraphy in assessing the complex regional pain syndrome (CRPS) type I in stroke patients METHOD: Forty three stroke patients were diagnosed as CRPS type I based on their symptoms and confirmed by three phase bone scintigraphy. Uptake ratio was calculated by dividing the radioactivity count on the affected side by that on the unaffected side in each phase. Mean uptake ratio was compared among the groups classified by the clinical diagnosis and by the response to treatment. In addition, uptake ratio was compared before and after treatment. RESULTS: Mean uptake ratio of the wrist in blood pool phase was significantly higher than other parts of the body (p<0.05). However, there was no significant difference among the groups classified by the clinical diagnosis nor by the response to treatment. The changes of uptake ratio were variable after treatment, but only the uptake ratio of the wrist in blood flow phase showed correlation with the degree of swelling. CONCLUSION: Uptake ratio of three phase bone scintigraphy was not correlated with clinical findings.

Isolated Splenic Metastasis of Sigmoid Colon Cancer Detected by 18F-FDG PET/CT / 핵의학분자영상

Splenic metastasis from colon carcinoma are rare and usually occur in the presence of disseminated visceral metastasis. The liver is the most common site of metastatic spread from colon cancer. Several hypotheses have attempted to explain the low incidence of splenic metastasis. It should be difficult for colorectal cancer cells to reach the spleen through the portal venous system, in which the blood flow is usually from the spleen to the liver. Reticuloendothelial system or rhythmic contraction of the spleen may squeeze out the tumor in the spleen. The absence of afferent lymphatic to the spleen, phagocytic activity and humoral anticancer substances are considered to be other reason for low incidence of splenic metastasis. We report the case of 18F-FDG PET/CT finding in a 70-year-old woman who develop isolated splenic metastasis of sigmoid colon cancer.

18F-FDG PET/CT in POEMS Syndrome / 핵의학분자영상

POEMS syndrome is a rare disorder, also known as Crow-Fukase, PEP or Takatsuki syndrome. The acronym, POEMS, represents polyneuropathy, organomegaly, endocrinopathy, M protein and skin change. However, there are associated features not included in the acronym such as sclerotic bone lesions, Castleman disease, papilledema, thromobocytosis, peripheral edema, ascites, effusion, polycythemia, fatigue and clubbing. In most cases, osseous lesions in POEMS syndrome present as an isolated sclerotic deposit and that reveal as osteosclerotic myeloma. Several cases of 18F-FDG PET in multiple myeloma involvements were reported, but there was no previous literature that reported FDG PET findings in POEMS syndrome. We describe here a 66-year-old patient with POEMS syndrome who underwent 18F-FDG PET/CT image.

The Clinical Significance of Routine Screening for the Renal Functional Asymmetry in Potential Live Kidney Donor

PURPOSE: An insufficiently functioning nephron might fail to meet the metabolic demands of a kidney donor, as well as the recipient, and may lead to hyperfiltration. An extreme asymmetry of the functional capacity of donor's bilateral kidneys might result in insufficiency to the recipient or donor. METHODS: Since February 1996, 99mTc-DTPA renal scintigraphy has been routinely included in the evaluation of renal functional asymmetry of a donor. The functional ratio of each kidney, using 99mTc-DTPA, as well as the serum creatinine (Scr) and creatinine clearance (Ccr), were measured and calculated using the 24-hour urine from a hundred donors. RESULTS: A hundred kidney donors were analyzed, including 62 male and 38 female donors. In the healthy donors, the average functional ratios of the left vs. the right kidneys were 52.5 vs. 47.5%. Seventy-three donors donated their left kidney and 27 their right. The Scr of the donors increased from 0.9+/-0.2 to 1.3+/-0.3 mg/dl after the nephrectomy. Both the Ccr in the 24 hour urine and the Ccr obtained using the Cockcroft and Gault formula of the remnant kidney after kidney donation increased from 54.5+/-11.4 to 68.0+/-14.3 ml/min/1.73 m2, and from 40.8+/-9.3 to 53.6+/-11.6 ml/ min/1.73 m2, respectively. CONCLUSION: Attention should be paid to the functional asymmetry of the kidney when choosing a kidney for donation. To protect the remnant kidney of a donor from hyperfiltration damage after donation, it is important to leave an adequate functioning nephron mass to meet the metabolic demands of the donor.

Efficiency of positron-emission tomography in two cases of idiopathic retroperitoneal fibrosis / 대한내과학회지

Idiopathic retroperitoneal fibrosis is a relatively rare disease that is characterized by the proliferation of fibrous tissue with an inflammatory process in the retroperitoneal cavity. It can cause an obstruction and compression of the ureter, abdominal aorta, and finally progress to renal failure. During the initial stages, the histology shows active inflammation. However, in the late stages, fibrous scarring occurs and the tissue becomes relatively avascular and acellular. Increased 18F-FDG accumulation was observed in our patient at the time of disease onset, which was attributed to the presence of inflammatory cells and actively metabolizing fibroblasts. We describe two patients with idiopathic retroperitoneal fibrosis, who were examined by 18F-FDG-PET, and discuss the efficiency of positron emission tomography in the diagnosis and management of idiopathic retroperitoneal fibrosis patients.

Changes of Glomerular Filtration Rate of Donated and Remnant Kidneys in a Week after Living Donor Kidney Transplantation / 대한이식학회지

PURPOSE: In living donor kidney transplantation, the initial function of donor's kidneys will be split into the function of the donor's remnant kidney and the recipient's implanted kidney. The question whether the function of these remnant and implanted kidneys will change after donation and transplantation was addressed. METHODS: The functional ratio of each kidney using (99m)Tc-Diethylenetriamine pentaacetic acid ((99m)Tc-DTPA) as well as serum creatinine (Scr, mg/dL) and 24-hour urine creatinine clearance (Ccr, mL/min/ 1.73 m(2)) from 100 donors were measured before donation. The kidney function was also calculated using Cockcroft-Gault formula (Ccr-CG, mL/min/ 1.73 m(2)). In donors and recipients, the Scr, Ccr, Ccr-CG were measured within a week after transplantation. RESULTS: The average functional ratio of the implanted kidney versus the remnant kidney before donation was 50.7 : 49.3. In implanted kidneys, the predonation Ccr and Ccr-CG were 56.7+/-9.4 mL/min/1.73 m(2) and 42.0+/-9.9 mL/min/1.73 m(2) which increased to 78.5+/-18.2 mL/min/1.73 m(2) and 53.2+/-16.4 mL/min/ 1.73 m(2) after transplantation. In remnant kidneys, the predonation Ccr and Ccr-CG were 54.5+/-10.9 mL/min/1.73 m(2) and 40.8+/-9.4/min/1.73 m(2) then increased to 68.0+/-14.2 mL/min/ 1.73 m(2) and 53.6+/-11.6 mL/min/1.73 m(2) after donation. CONCLUSION: Kidney transplantation from a living donor should be encouraged based on the total functional benefit of both donors and recipients after kidney donation and implantation.

Correlation of Hepatic 18F-Fluorodeoxyglucose Uptake with Fatty Liver / 핵의학분자영상

PURPOSE: Liver demonstrates heterogeneous FDG uptake and sometimes it shows abnormally increased uptake even though there is no malignant tissue. However, there was no previous study to correlate these various pattern of hepatic FDG uptake with benign liver disease. Therefore, we evaluated the significance of hepatic FDG uptake associated with various clinical factors including fatty liver, liver function tests and lipid profiles. MATERIALS AND METHODS: We reviewed a total of 188 patients (male/female: 120/68, mean age: 50+/-9) who underwent PET/CT for screening of malignancy. Patients with DM, impaired glucose tolerance, previous severe hepatic disease or long-term medication history were excluded. The FDG uptake in liver was analyzed semi-quantitatively using ROI on transaxial images (segment 8) and we compared mean standardized uptake value (SUV) between fatty liver and non-fatty liver group. We also evaluated the correlation between hepatic FDG uptake and various clinical factors including serum liver function test (ALT, AST), gamma-GT, total cholesterol and triglyceride concentration. The effect of alcoholic history and body mass index on hepatic FDG uptake was analyzed within the fatty liver patients. RESULTS: The hepatic FDG uptake of fatty liver group was significantly higher than that of non-fatty liver group. Serum total cholesterol and triglyceride concentration showed significant correlation with hepatic FDG uptake. However, there was no significant correlation between other factors (ALT, AST, and gamma-GT) and FDG uptake. Also there was no difference of mean SUV between normal and abnormal groups on the basis of alcoholic history and body mass index within fatty liver patients. Fatty liver and high serum triglyceride concentration were the independent factors affecting hepatic FDG uptake according to multivariate analysis. CONCLUSION: In conclusion, hepatic FDG uptake was strongly correlated with fatty liver and serum triglyceride concentration.

Usefulness of Low Dose Oral Contrast Media in 18F-FDG PET/CT / 핵의학분자영상

PURPOSE: The standard protocol using large volume of oral contrast media may cause gastrointestinal discomfort and contrast-related artifacts in PET/CT. The aim of this study was to evaluate the usefulness of low dose oral contrast in 18F-FDG PET/CT. MATERIALS AND METHODS: We retrospectively reviewed the whole-body PET/CT images in a total of 435 patients. About 200 ml of oral contrast agent (barium sulfate) was administered immediately before injection of 18F-FDG. The FDG uptake of intestines was analyzed by visual and semi-quantitative method on transaxial, coronal and saggital planes. RESULTS: Seventy (16%, 113 sites) of 435 images showed high FDG uptake (peak SUV > 4); 50 (74%, 84 sites) with diffuse and 20 (26%, 29 sites) with focal uptake. The most commonly delivered site of oral contrast media was small bowel (n=27, 39%). On PET/CT images, FDG uptake coexisted with oral contrast media in 26 patients (54%, 38 sites) with diffuse pattern and 9 (45%, 9 sites) with focal pattern, and by sites, those were 38 (45%) and 9 (31%), respectively. In small bowel regions, the proportion of coexistence reached as high as 61% (29/47 sites). A visual analysis of available non-attenuation corrected PET images of 27 matched regions revealed no contrast-related artifact. CONCLUSION: We concluded that the application of low dose contrast media could be helpful in the evaluation of abdominal uptake in the FDG PET/CT image.

Determination of Tumor Volume in PET for the Radiation Treatment Planning : Computer Simulation / 의학물리

The utilization of PET has been increased so fast since the usefulness of the PET has been proved in various clinical and research fields. Among the many applications, the PET is especially useful in oncology and most of the clinical PET scans are performed for the oncologic examination including the different diagnosis of malignant and benign tumors and assessment of the treatment effects and recurrent tumors. As the PET-CT scanners are widely available, there is increasing interest in the application of the PET images to the radiation treatment planning. Although the CT images are conventionally used for the target volume determination in the radiation treatment planning, there are fundamental limitation in use of only the anatomical information. Therefore, the volume determination of the functionally active tumor region using the PET would be important for the treatment planning. However, the accurate determination of the tumor boundary is not simple in PET due to the relatively low spatial resolution of the currently available PET scanners. In this study, computer simulations were performed to study the relationship between the lesion size, PET resolution, lesion to background ratio and the threshold of image intensity to determine the true tumor volume.

Assessment of Myocardial Viability Using PET / 대한핵의학회잡지

The potential for recovery of left ventricular dysfunction after myocardial revascularization represents a practical clinical definition for myocardial viability. The evaluation of viable myocardium in patients with severe global left ventricular dysfunction due to coronary artery disease and with regional dysfunction after acute myocardial infarction is an important issue whether left ventricular dysfunction may be reversible or irreversible after therapy. If the dysfunction is due to stunning or hibernation, functional improvement is observed. but stunned myocardium may recover of dysfunction with no revascularization. Hibernation is chronic process due to chronic reduction in the resting myocardial blood flow. There are two types of myocardial hibernation: "functional hibernation" with preserved contractile reserve and "structural hibernation" without contractile reserve in segments with preserved glucose metabolism. This review focus on the application of F-18 FDG and other radionuclides to evaluate myocardial viability. In addition the factors influencing predictive value of FDG imaging for evaluating viability and the different criteria for viability are also reviewed.

Giant Neonatal Hemangioendothelioma of the Liver Diagnosed by 99mTc-RBC Scintigraphy

Infantile hemangioendothelioma (IHE) is a benign tumor of the liver composed of anastomosing vascular channels lined by plump endothelial cells. The major clinical findings of IHE are abdominal mass, hepatomegaly, cutaneous hemangioma, congestive heart failure, anemia and disseminated intravascular coagulopathy. Precise diagnosis of IHE is crucial because medical therapies using steroid and/or interferon can be tried unless there are grave compressive symptoms. Along with CT scan and MRI studies, scintigraphic evaluation with 99mTc-RBC offers an accurate method of identification of these lesions, and allows differentiation from other common primary or secondary hepatic masses. We report two cases of giant IHE of the liver those were diagnosed with 99mTc- RBC scan and confirmed with pathologic evaluation after surgical removal.

F-18 FDG Uptake in a Toxic Autonomous Thyroid Nodule / 대한핵의학회잡지

No abstract available.

Usefulness and Limitation of 24 Hour Reinjection Images to Assess Myocardial Viability in Patients with Acute Myocardial Infarction

OBJECTIVE: The study was performed to evaluate whether thallium reinjection (RI) distinguishes viable from nonviable myocardium among myocardial segments which showed persistent perfusion defect (PD) in patients with acute myocardial infarction (AMI). MATERIALS AND METHODS: We studied 22 patients underwent PTCA after AMI. SPECT was performed in all patients using dipyridamole stress- 4 hour redistribution (RD) followed by 24 hour RI protocols. Dysfunctional segs were classified into 5 groups: 1) normal, 2) reversible, 3) mild to moderate PD, 4) severe PD and 5) reverse redistribution (RR). All patients underwent follow up echocardiography after 4 months to assess regional wall motion (WM) improvement such as a criteria of viable myocardium. RESULTS: A total of 127 segs with abnormal WM was analyzed. Of 74 segs with PD, 17 (23%) showed enhanced uptake after 24 hour RI. Five of 17 segs (29%) with PD that responded to RI with enhanced thallium uptake showed WM improvement. WM improvement were seen in the 24 of 57 segs (42%) not responding to RI. All four segs (100%) with RR that responded to RI showed improvement. WM improvement were not seen in the 5 of 8 segs (71%) with RR not responding to thallium RI. Eleven (73%) of 15 segs with mild-moderate PD after RI showed improvement, but 33% of segs with severe PD after RI did not showed improvement. Segs with mild-moderate PD after RI and fill in after RI showed improvement in comparison to segs with severe PD after RI(p<0.05). CONCLUSIONS: These data indicate that because only small proportion of PD showed further perfusion improvement after RI and predictive value by the uptake after RI was low, there was limited role of RI after myocardial infarction. Usefulness of RI could be found in segs showing RR responding to RI in AMI reflects viable myocardium.

Usefulness of 201Tl Myocardial Perfusion SPECT in Prediction of Left Ventricular Remodeling following an Acute Myocardial Infarction / 대한핵의학회잡지

PURPOSE: We investigated the role of myocardial perfusion SPECT in prediction of ventricular dilatation and the role of revascularization including thrombolytic therapy and PTCA in prevention of ventricular dilatation after an acute myocardial infarction (AMI). MATERIALS AND METHODS: We performed dipyridamole stress, 4 hour redistribution, and 24 hour reinjection Tl-201 SPECT in 16 patients with AMI two to nine days after attack. Perfusion and wall motion abnormalities were quantified by perfusion index (PI) and wall motion index (WMI). Left ventricular ejection fraction (LVEF), WMI and ventricular volume were measured within 1 week of AMI and after average of 6 months. According to serial changes of left ventricular end-diastolic volume (LVEDV), patients were divided into two groups. We compared WMI, PI and LVEF between the two groups. Relationships among degree of volume, stress-rest PI, WMI, CKMB, Q wave, LVEF and revascularization were analysed using multivariate analysis. RESULTS: Only initial rest perfusion index was significantly different between the two groups (p<0.05). While initial LVEF, stress PI, CKMB, trial of revascularization procedure, presence of Q wave and WMI were not significantly different between the two groups. Eight of 16 patients (50%) showed LV dilatation on follow-up echocardiography. Three of 3 patients (100%) who did not undergo revascualrization procedure documented LV dilatation. And only 5 (38%) of the remaining 13 patients who underwent revascularization revealed LV dilatation. There was no difference in infarct location between the two groups. By multivariate linear regression analysis in patients only undergoing revascularization, rest perfusion index was the only significant factor. CONCLUSION: Myocardial perfusion SPECT performed prior to revascularization was useful in prediction of LV dilatation after an AMI. Rest perfusion index on myocardial perfusion plays as a significant predictor of left ventricular dilatation after AMI. And revascularization appears to be a valuable procedure in alleviating LV dilatation after AMI with or without viable myocardium in a limited number of patients studied retrospectively.

The Usefulness of Diagnostic Scan Using Technetium-99m Pertechnetate Scintigraphy prior to the First Ablative Radioiodine Treatment in Patients with Well Differentiated Thyroid Carcinoma: A Comparative Study with Iodine-131 / 대한핵의학회잡지

PURPOSE: A prospective comparison was made between imaging with Tc-99m pertechnetate (Tc-99m) and Ioine-131 (I-131) for the detection of residual and metastatic tissue after total thyroidectomy in patients with well-differentiated thyroid carcinoma. MATERALS AND METHODS: Initially our patients had imaging with Tc-99m, followed by I-131 within 3 days. The study included 21 patients who had ablation with high dose of I-131 ranging from 100 mCi to 150 mCi. Planar and pinhole images were acquired for both Tc-99m and I-131. Diagnostic images of Tc-99m and I-131 were compared with post-therapy images. Degree of uptake on Tc-99m and I-131 images was scored by four point scale and compared. RESULTS: The results of the Tc-99m study were: 16 of 19 studies (84%) were positive on simple planar images, but 19 of 20 studies (95%) were positive on pinhole images. Conventional I-131 diagnostic imaging on the other hand showed that all studies (100%) were positive on both planar and pinhole images. There was a significant difference in degree of uptake between Tc-99m and I-131 planar images (p<0.05). Only one case of Tc-99m scintigraphy was negative on both planar and pinhole studies (false negative). There was no distant metastasis on the therapeutic I-131 images. CONCLUSION: Tc-99m scan using pinhole in certain clinical situations is an alternative to the I-131 scan in detecting thyroid or lymph node metastasis prior to the first ablative treatment after thyroidectomy for well-differentiated thyroid carcinoma.