Usefulness of 18F-FDG PET/CT in Cutaneous Melanoma Patients with Negative Sentinel Lymph Nodes and High Clark Levels.

OBJECTIVE: We investigated the utility of PET/CT in cutaneous melanoma (CM) patients with pathological negative sentinel lymph nodes (SLN), within the first year. METHODS: The results of PET/CTs and SLN biopsy (SLNB) in 65 patients (39 male and 26 female, mean age 53.8) with a PET/CT in the first postoperative year were evaluated. Within this cohort, the utility of early PET/CT imaging was assessed in patients with negative SLNB. McNemar test was used to compare PET/CT findings with SLNB results. RESULTS: Out of 43 patients with pathologically positive SLNs, 23 patients (53.5%) had positive and 20 patients (46.5%) had negative findings on PET/CT within the first postoperative year. On the other hand, PET/CT results of 22 patients with negative SLNBs were found to be negative in 19 patients (86.4%) and positive in 3 patients (13.6%). For the patients with negative SLNB results, the detection rate of distant metastasis with PET/CT was significantly lower (p<0.001) than that in patients with positive SLNBs. CONCLUSION: Our results showed that 18F-FDG PET/CT will most likely (86.4%) be negative during the first postoperative year in patients with a negative SLNB. Therefore, it is concluded that this modality would not provide any significant clinical contribution within this time frame.

Diagnostic value of F-18 FDG PET/CT in patients with spondylodiscitis: Is dual time point imaging time worthy?

PURPOSE: In this retrospective study, we aimed to investigate the value of FDG-PET/CT in the diagnosis of spondylodiscitis (SD), the significance of dual time point imaging (DTPI) for SD diagnosis and the worth of SUVmax data for distinguishing tuberculous vs. non-tuberculous SD. MATERIALS AND METHODS: 32 patients with suspected SD were scanned with FDG-PET/CT. For quantitative analysis maximum standardized uptake value (SUVmax) of the lesion area was measured. Nineteen patients had DTPI of FDG-PET/CT. The final diagnoses were achieved by histopathological, microbiological, and clinical results. RESULTS: Specific pathogens were isolated in 21 patients; other patients were accepted as nonspecific bacterial SD. In all patients, FDG-PET/CT results were compatible with SD diagnosis. The SUVmax data for tuberculous and non-tuberculous SD and DTPI results were statistically insignificant. CONCLUSION: FDG-PET/CT is a successful modality for SD diagnosis; additionally, DTPI protocol for FDG-PET/CT in SD diagnosis and SUVmax data for differentiation between non-tbc SD and tbc SD are useless.

Comparison of Tc-99m pertechnetate images with dual-phase Tc 99m MIBI and SPECT images in primary hyperparathyroidism.

BACKGROUND: The purpose of this study was to evaluate the value of Tc-99m pertechnetate planar, dual-phase MIBI and MIBI-SPECT images in the determination and localization of parathyroid lesions. MATERIALS AND METHODS: In this study, 38 patients who underwent operation for primary hyperparathyroidism were included. Tc-99m pertechnetate planar-pinhole imaging of the neck and then MIBI planar and SPECT images in supine position was performed. Late SPECT images were acquired 120 minutes after the injection. Early and late MIBI images were quantitatively evaluated. RESULTS: Of the 38 patients, 30 of them had adenoma, 2 patients had hyperplasia and 6 of them were normal on planar images. Thirty-four of 38 patients were positive on SPECT images. SPECT images of the patients with positive results were matched with pathology results. CONCLUSION: As a result, Tc-99m pertechnetate planar-pinhole, Tc-99m MIBI planar and SPECT images are useful for localization of parathyroid lesions especially in multinodular thyroid gland. However, US or CT images are necessary for more accurate localization and Tc-99m pertechnetate images are useful for interpreting and comparing with the early and late MIBI images.

Clinical value of technetium-99m-labeled octreotide scintigraphy in local recurrent or metastatic medullary thyroid cancers: a comparison of lesions with 18F-FDG-PET and MIBI images.

AIM: Various studies have been conducted for determining the most optimal method for the early diagnosis of local recurrent or distant metastatic thyroid cancers. The aim of this study was to evaluate the clinical utility of technetium-99m (Tc-99m)-labeled octreotide derivatives in the detection of recurrence or distant metastases in medullary thyroid cancer patients and to compare the lesions with those detected using 18F-fluorodeoxyglucose (18F-FDG)-PET and Tc-99m MIBI studies in the same patient group. PATIENTS AND METHODS: Sixteen medullary thyroid cancer patients [two male and 14 female; mean age 52.0 ± 14.1 years (range 13-72 years)] were included in this study. All patients underwent a whole-body scan 1 and 4 h after injection with octreotide derivatives and single photon emission computed tomography images were taken of the sites suspicious for metastasis. The lesions seen in Tc-99m HYNIC octreotide studies were compared with those seen in 18F-FDG-PET and Tc-99m MIBI studies. RESULTS: Among the Tc-99m-labeled octreotide scintigraphy studies, nine were evaluated as true positive (56.2%) and one was evaluated as false positive (6.2%); six were false negative (37.5%). In 16 patients, the total number of lesions seen on octreotide scintigraphy was 21. Thirteen of the 16 patients underwent 18F-FDG-PET imaging. Of the 13 patients studied, 10 showed true-positive (76.9%) and three showed false-negative (23.1%) results. The total number of lesions seen on 18F-FDG-PET was 23. The Tc-99m MIBI study yielded positive results in seven of 16 patients (43.7%) and negative results in nine patients (56.3%). The total number of lesions on Tc-99m MIBI was 12. CONCLUSION: The Tc-99m-labeled somatostatin receptor scintigraphy analogs HYNIC-tyrosine octreotide and HYNIC-TATE are useful imaging alternatives in somatostatin receptor-expressing thyroid cancers. Radiolabeling using these analogs is easy and they are readily available for routine use.

Comparison of 99mTc-HYNIC-TOC and HYNIC-TATE octreotide scintigraphy with FDG PET and 99mTc-MIBI in local recurrent or distant metastatic thyroid cancers.

AIM: There have been various studies for early diagnosis of local recurrent or distant metastatic thyroid cancers. The aim of this study is to evaluate the clinical utility of 99mTc-HYNIC-TOC and 99mTc-HYNIC-TATE, octreotide derivatives, to detect recurrences or distant metastases in 131I-negative thyroglobulin positive thyroid cancer patients and to compare the lesions with FDG PET and 99mTc-MIBI studies in the same patient group. PATIENTS AND METHODS: Twenty differentiated thyroid cancer patients, 7 male and 13 female, mean age 54.6 ± 15.3 (range 13-78 years), were included in this study. Eighteen patients had papillary thyroid cancer and 2 had follicular thyroid cancer. Fifteen patients received HYNIC-TOC and 5 patients received HYNIC-TATE as a radiopharmaceutical. All patients underwent whole-body scan 1 and 4 hours after injection of octreotide derivatives and SPECT imagings were performed from the suspicious sites. The lesions that were seen in 99mTc-HYNIC-TOC and 99mTc-HYNIC-TATE studies were compared with 99mTc-MIBI and FDG-PET studies. RESULTS: Among 99mTc-HYNIC-TOC and 99mTc-HYNIC-TATE scintigraphies, 15 patient studies were evaluated as true positive (75%) and 5 were false negative (25%). The total number of lesions in octreotide scintigraphy was 48 in 20 patients. Of 20 patients, 19 had FDG-PET study, 15 of them were evaluated as true positive (78.9%), and 4 them were evaluated as false negative (21.1%). Total number of lesions in FDG PET was 74. 99mTc-MIBI study was positive in 11 patients (55%) and negative in 9 patients (45%). Total number of lesions in 99mTc-MIBI was 25. CONCLUSION: Technetium-labeled somatostatin receptor scintigraphy analogues HYNIC-TOC and HYNIC-TATE are useful imaging alternatives in somatostatin receptor expressing thyroid cancer patients. Radiolabeling is easy and they are readily available for routine use.

The Diagnostic Role of FDG PET/CT in Patients with Fever of Unknown Origin.

OBJECTIVE: Fever of unknown origin (FUO) is a challenge for the physician and needs use of clinical, laboratory, and imaging studies and also invasive and/or non-invasive interventions to detect the etiology. The aim of present study was to assess the role of FDG PET/CT in determining the etiology in patients with FUO. MATERIAL AND METHODS: Twenty-four patients (median age 52, range 5-77 years, 6 female, 18 male) who were diagnosed with FUO were retrospectively analyzed in this study. Before the FDG PET/CT studies, none of them had a definitive reason for their diseases investigated by conventional radiological or scintigraphic methods, clinical and laboratory observations. RESULTS: The positive result was achieved in 19 (79.2%) of 24 patients as findings of the FDG PET/CT. However, FDG PET/CT was useful for definitive diagnosis in 12 (63.2%) of 19 positive patients. Malignant diseases were determined to be the underlying cause of FUO in 5 (41.6%) of 12 patients. Noninfectious inflammatory causes were detected in 2 (16.7%) patients, infections were exhibited in 3 (25%) patients, and miscellaneous diseases demonstrated in 2 (16.7%) patients. In 7 patients the detected pathological uptakes on FDG PET/CT were not helpful for the definitive diagnosis. In remaining 5 patients who showed no pathological uptake in the FDG PET/CT, diagnosis could not be established by other methods, as well. The sensitivity, specificity, and positive and negative predictive values for the determination of FUO etiology were 92.3%, 45.4%, 63.1%, and 100% for FDG PET/CT. CONCLUSION: Our results demonstrate that FDG PET/CT seems to have considerable contribution to reveal the reason of undiagnosed patients with FUO investigated by conventional diagnostic methods, clinical and laboratory observations. CONFLICT OF INTEREST: None declared.

Temporal relationship between gastroesophageal reflux and rate of gastric emptying in children.

OBJECTIVES: There are conflicting reports for the relationship of reflux and the gastric emptying rate. In addition, the acquisition period is not well defined for the gastroesophageal reflux studies. The aim of our study was to evaluate the temporal distribution of the reflux episodes and to evaluate whether the gastric emptying rate changed with the gastroesophageal reflux time or amount. METHODS: We used radionuclide scintigraphy to evaluate 211 pediatric patients (0-10 years of age). Scintigraphic studies were performed by acquiring 15 s images for 1 h in a supine position after ingesting milk containing 0.5 mCi (18.5 MBq) Tc-99m colloid. Reflux episodes were calculated every 10 min for each patient who had reflux. The gastric emptying rate was measured by drawing an region of interest over the gastric activity. RESULTS: Gastric reflux was observed in 104 patients (49.28%). The number of reflux episodes was higher in the first and second 10 min (33.7 and 29.1% respectively). The lowest reflux episode was observed in the last 10 min (between 50 and 60 min) (2.6%) suggesting that the reflux episode was decreasing by the gastric emptying. Within the first 30 min, reflux was observed in 98 of 104 patients (94.23%). The gastric emptying rate was calculated to be 73 min in patients with a higher incidence of reflux and 62 min in patients who had delayed and lower incidence of reflux episodes. In 104 patients, the average gastric emptying rate was 71.60 min. There were no significant differences in the gastric emptying rates between patients who had reflux episodes beginning in the first 30 min of the study and those who had reflux episodes in the last 30 min of the study (P>0.05). CONCLUSION: This study has suggested that the number of reflux episodes were not related with the gastric emptying rate. However, reflux could be observed in a higher frequency before gastric emptying, which also suggested that a 30-min period may be sufficient when reflux is shown early. In negative cases, a 60-min acquisition time is recommended for the diagnosis of gastroesophageal reflux.

The value of different washout parameters in the evaluation of renal transplants by technetium-99m-ethylene- l-l-dicysteine.

Technetium-99m-ethylene-l-l-dicysteine ((99m)Tc-EC) is an agent with a potential for renal imaging. It is reported that EC uses the same tubular transporter system as ortho-hippurate (OIH) and mercaptoacetyltriglycine (MAG3) and that this agent has good imaging properties and higher renal clearance than MAG3. In this study we used (99m)Tc-EC to compare different washout parameters in renal transplanted patients. Sixty nine scans in 55 patients (38 males, 17 females) were performed with (99m)Tc-EC during the follow-up period after kidney transplantation. After bolus injection of 280MBq (99m)Tc-EC, 60x1sec and 29x1min images were taken in anterior position. Perfusions of transplanted kidneys were examined visually and perfusion indices (PI) were calculated according to Hilson's method. The semiquantitative washout parameters such as 20 and 30min to peak activity ratios and 20 and 30min to 3min activity ratios were calculated. The patients were clinically evaluated by nephrologists experienced in renal transplantation cases and followed-up by serum creatinine and blood urea nitrogen determinants which were checked every postoperative day until stabilized to a optimal level for each patient. Two standard deviations above the mean values derived from all cases with normal functioning transplanted kidneys were calculated for each method. Then, these values served as the threshold to differentiate the pathological cases respectively. Of the 69 total studies performed, we found 34 normal kidneys, 14 rejections, 19 acute tubular necrosis (ATN) and 2 cyclosporin A toxicity cases. The number of abnormal cases detected with 30/3min, 30/max, 20/3min and 20/max indices were 27, 26, 24, and 18, respectively. In conclusion, we strongly recommend in studying renal transplants to consider the activity at the 3(rd) min post injection as a reference point instead of the time to maximum activity for washout index calculation. If, for any reason the time to maximum counts using (99m)Tc-(peak activity) is prefered, then the period of study should not be performed for less than 30min to achieve reliable results.

Intravascular radiation therapy with a Re-188 liquid-filled balloon in patients with in-stent restenosis.

OBJECTIVE: The aim of this study was to evaluate the feasibility and safety of intravascular radiation therapy (IVRT) using Re-188 filled balloon system in patients with in-stent stenosis. METHODS: A total of 39 patients with in-stent restenosis were enrolled as the IVRT (22 patients) and control groups (17 patients) of this study after a successful coronary angioplasty. For irradiation the angioplasty balloon was replaced by a noncompliant balloon of the same diameter but 10 mm longer in length with a proximal and distal radio-opaque marker to deliver the dose of 18 Gy at 0.5 mm depth from the surface of the balloon into the vessel wall. Angiographic follow-up was performed after 6 months. RESULTS: The length of the irradiated segment was between 9.14 and 22 mm and the diameter between 2.5 and 3 mm. In the IVRT group, two patients who did not receive antiplatelet therapy had myocardial infarction. Four patients who presented with stable angina earlier also had angiographically documented in-stent occlusion (two patients) and edge stenosis (two patients) of the target lesion and received angioplasty (18.1%). In the control group, three patients with recurrent angina and four asymptomatic patients had documented in-stent occlusion angiographically at 6 months and these seven patients underwent target lesion revascularization (41.2%). The overall restenosis rate in the IVRT and control groups were 23.91 and 39.86%, respectively (P=0.013). No complications were documented, except anginal pain and ST segment changes. CONCLUSION: Our results indicated that the Re-188 liquid-filled balloon is feasible, safe, and effective in patients with in-stent restenosis.

Treatment of iodine-negative thyroglobulin-positive thyroid cancer: differences in outcome in patients with macrometastases and patients with micrometastases.

PURPOSE: During the follow-up of patients with well-differentiated thyroid carcinoma, some patients have elevated serum thyroglobulin (Tg) levels without any evidence of radioiodine accumulation on diagnostic whole-body scan (d-WBS). The treatment strategy in these patients is considered a clinical dilemma, with some groups recommending blind use of high-dose radioiodine therapy. The aim of this study was to evaluate whether or not high doses of radioiodine have beneficial effects in these patients. METHODS: Twenty-seven patients were included in the study. All patients had negative d-WBS and elevated levels of Tg. All received high doses of radioiodine. The mean follow-up period was 6.3+/-5.8 years. There were 11 patients with macrometastases and 16 with micrometastases. RESULTS: Post-treatment WBS revealed radioiodine accumulation in 19 of 24 (79%) patients. Serum Tg levels were decreased in 8 of 16 (50%) patients. Among patients with micrometastases, five out of seven (71%) demonstrated a decrease in serum Tg levels. Among patients with macrometastases, three out of nine (33%) demonstrated a decrease in Tg values and three (33%) have died due to metastatic thyroid cancer. CONCLUSION: Radioiodine treatment may have a beneficial therapeutic effect in patients who have elevated levels of serum Tg and negative d-WBS. This is especially true in those patients with micrometastases; in patients with macrometastases, a beneficial effect of this approach may be observed less frequently.

Is furosemide administration effective in improving the accuracy of determination of differential renal function by means of technetium-99m DMSA in patients with hydronephrosis.

It has been suggested that determination of differential renal function (DRF)using technetium-99m dimercaptosuccinic acid (DMSA) may lead to overestimation of the function of an obstructed kidney in patients with excretion abnormalities owing to pelvic retention of DMSA. Recently published guidelines have recommended use of furosemide injection when calculating DRF in these particular patients. The aim of this study was to evaluate the effect of diuretic administration on the determination of DRF using DMSA scintigraphy. For this purpose, 19 patients, aged from 1 month to 69 years (19.4+/-24.8 years, 15 males, 4 females), in whom pelvic retention had been documented by diuresis scintigraphy were included in the study. DMSA scintigraphy was performed in all patients 2-4 h after injection and six planar images were obtained. Immediately after the standard study, furosemide was injected in all patients, and 30 min later the same number of images was obtained. DRF was calculated for each patient and from each DMSA study by using the arithmetic mean method. The difference between two studies (DMSA scintigraphy with or without furosemide administration and diuresis scintigraphy) was expressed as a percentage of the mean value of the two studies (the DRF value of the affected kidney was thus taken into account). The mean of the differences represented the systemic bias and the SD of the mean of the differences represented the precision of the technique. In seven patients, diuresis renography revealed an obstructive curve pattern. We did not observe any significant difference between the DRF values obtained before and after diuretic administration ( P>0.5). When we compared DRF values obtained from standard and from diuretic DMSA studies, the mean of the differences was only 0.3% and the SD was only 1.2%. There was also no significant difference in DRF between patients with the obstructive curve pattern and those with a dilated renogram curve pattern (with washout of activity during the second phase of the study) ( P>0.1). In conclusion, we did not observe interference from pelvicalyceal activity in patients with documented pelvic retention and infer that diuretic administration may be a useless intervention for improving the accuracy of determination of DRF.