Clinical conditions related to positive thymic uptake on I-131 post-therapeutic scans in thyroid cancer patients.

OBJECTIVE: Thymic uptake is a well-known cause of false-positives on I-131 post-therapeutic scans. This study identified the clinical conditions associated with thymic uptake on I-131 post-therapeutic scans in thyroid cancer patients. DESIGN: This was a retrospective study that investigated the clinical conditions associated with thymic uptake on I-131 post-therapeutic scans of patients obtained between January 2010 and December 2010. PATIENTS: Six hundred and eighty-five patients were included follwing a therapeutic dose of I-131 (3.7-9.25 GBq). METHODS: We reviewed the patients' clinical characteristics, including age, sex, histology, serum thyrotropin (TSH) stimulation regimen, prior history of RAI therapy, and labaratory parameters such as the serumTSH, thyroglobulin, and anti-thyroglobulin antibody. At follow-up, patients were assessed in terms of disease-free status, structural persistence, and biochemical disease. RESULTS: In total, 107 I-131 post-therapeutic scans (15.6%) evidenced thymic uptake. The mean age of the positive thymic uptake group was significantly lower than that of the negative group (p < .001). Significant indicators for thymic uptake were thyroid hormone withdrawal and a history of repeated radioactive iodine (RAI) therapy (p < .05). Logistic regression analysis showed that young age and a history of repeated RAI therapy correlated with thymic uptake (p < .001). At the end of follow-up, 487 patients (86.5%) were disease-free, 44 (7.8%) still had biochemical disease, and 32 (5.7%) showed structural persistence. Ten patients (11.5%) in the positive thymic uptake group and 22 (4.6%) in the negative thymic uptake group showed structural persistence. Five patients (5.7%) in the positive thymic uptake group and 39 (8.2%) in the negative thymic uptake group had biochemical disease. The final follow-up results of the two groups were statistically different. CONCLUSIONS: Thymic uptake tended to be more prominent in young patients with a history of repeated RAI therapy. Structural recurrence during follow-up was much more common in the positive thymic uptake group, while the incidence of biochemical recurrence during follow-up was higher in the negative thymic uptake group.

Prognostic value of pretreatment F-18 fluorodeoxyglucose PET/CT in colorectal cancer with unresectable metastasis.

PURPOSE: The aim of the study was to assess the prognostic value of pretreatment PET/computed tomography (CT) scans in colorectal cancer (CRC) patients with unresectable metastasis. MATERIALS AND METHODS: We retrospectively reviewed the pretreatment PET/CT images of 82 CRC patients with unresectable metastasis and their medical records. On PET/CT images, maximum standardized uptake value (SUVmax) of primary tumor, highest SUVmax of metastatic tumors and number of metastatic organs were identified. The patients were further divided into single and multiple organ metastases groups according to the extent of disease. Survival analysis was performed with the clinical variables and metabolic parameters from PET/CT. RESULTS: In a total of 82 patients, the age of patients, highest SUVmax of metastatic tumors and number of metastatic organs were independent prognostic factors for overall survival (OS) (all P < 0.05), whereas the SUVmax of primary tumor was not. On multivariate analysis, only the SUVmax of metastatic tumor was a significant prognostic factor in the single organ metastasis group (P = 0.047), whereas the age and highest SUVmax of metastatic tumors were independent prognostic factors in the multiple organ metastases group (all P < 0.05). CONCLUSION: The highest SUVmax of metastatic tumors was an independent prognostic factor for OS in CRC patients with unresectable metastasis.

Factors affecting the negative predictive value of positron emission tomography/computed tomography for axillary lymph node staging in breast cancer patients.

BACKGROUND/OBJECTIVE: Axillary lymph node staging (ALNS) is an important step in the treatment of breast cancer and sentinel lymph node biopsy (SLNB) is a standard procedure for ALNS. Recently, the use of positron emission tomography/computed tomography (PET/CT) for whole body staging in patients with breast cancer has been increasing. The negative predictive value (NPV) of the specific diagnostic modality is the crucial value for excluding axillary lymph node metastasis (ALNM) and guiding the decision not to proceed with axillary lymph node dissection. The aim of this study was to identify patient groups in which PET/CT yields a high NPV for ALNS. METHODS: We reviewed data from the records of 262 patients with breast cancer who underwent PET/CT before surgery between February 2009 and March 2018. We searched for factors associated with pathological axillary lymph node metastasis in patients with negative ALNM on PET/CT. Then, we calculated the NPV of PET/CT for ALNS in the patient group without the identified factors and in all patients. RESULTS: Age ≥75 years and tumor size on ultrasonography (US) ≥ 15 mm were the associated factors; the NPV of PET/CT in patients without these factors compared to all patients was 97.2% versus 88.7%. CONCLUSION: The NPV of PET/CT for ALNS in patients younger than 75 years and with tumor size on US < 15 mm is higher than that in all patients and comparable to the NPV of SLNB reported in previous studies (90.1-97.0%).

Comparison of Natural Course between Thyroid Cancer Nodules and Thyroid Benign Nodules.

BACKGROUND: The natural course of thyroid cancer nodules and benign nodules is different. This study was to compare the changes in size between thyroid cancer nodules and thyroid benign nodules. The risk factors associated with the changes of thyroid cancer nodules were assessed. METHODS: This study contains retrospective observational and prospective analysis. A total of 113 patients with 120 nodules were recruited in the cancer group, and 116 patients with 119 nodules were enrolled in the benign group. Thyroid ultrasonography was performed at least two times at more than 1-year interval. RESULTS: The mean follow-up durations were 29.5±18.8 months (cancer group) and 31.9±15.8 months (benign group) (P=0.32). The maximum diameter change in length was 0.36±0.97 mm/year in the cancer group and -0.04±0.77 mm/year in the benign group (P<0.01). The volume was significantly increased in the cancer group compared with the benign group (0.06±0.18 mL/year vs. 0.004±0.05 mL/year, respectively, P<0.01; 26.9%±57.9%/year vs. 1.7%±26.0%/year, P<0.01). Initial maximum diameter (ß=0.02, P<0.01) and initial volume (ß=0.13, P<0.01) were significantly associated with volume change (mL)/year. Initial maximum standardized uptake value did not predict the nodule growth. CONCLUSION: It is suggested that thyroid cancer nodules progress rapidly compared with benign nodules. Initial size and volume of nodule were independent risk factors for cancer nodule growth.

Clinical Characteristics of False-Positive Lymph Node on Chest CT or PET-CT Confirmed by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration in Lung Cancer.

BACKGROUND: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a standard procedure to evaluate suspicious lymph node involvement of lung cancer because computed tomography (CT) and 18F-fluorodeoxyglucose positron emission tomography-CT (PET-CT) have limitations in their sensitivity and specificity. There are a number of benign causes of false positive lymph node such as anthracosis or anthracofibrosis, pneumoconiosis, old or active tuberculosis, interstitial lung disease, and other infectious conditions including pneumonia. The purpose of this study was to evaluate possible causes of false positive lymph node detected in chest CT or PET-CT. METHODS: Two hundred forty-seven patients who were initially diagnosed with lung cancer between May 2009 and December 2012, and underwent EBUS-TBNA to confirm suspicious lymph node involvement by chest CT or PET-CT were analyzed for the study. RESULTS: Of 247 cases, EBUS-TBNA confirmed malignancy in at least one lymph node in 189. The remaining 58 patients whose EBUS-TBNA results were negative were analyzed. Age ≥65, squamous cell carcinoma as the histologic type, and pneumoconiosis were related with false-positive lymph node involvement on imaging studies such as chest CT and PET-CT. CONCLUSION: These findings suggest that lung cancer staging should be done more carefully when a patient has clinically benign lymph node characteristics including older age, squamous cell carcinoma, and benign lung conditions.

Ductal carcinoma in situ and ductal carcinoma in situ with microinvasion: correlation of FDG uptake with histological and biological prognostic factors.

BACKGROUND: Several studies investigated the correlation between the intensity of fluorodeoxyglucose (FDG) uptake and some histological and biological characteristics in breast cancer. Ductal carcinoma in situ (DCIS) is generally thought to be a precursor lesion of invasive breast cancer. The aim of this study was to assess the correlation between FDG uptake values on positron emission tomography/computed tomography (PET/CT) with histological and biological prognostic factors in DCIS and ductal carcinoma in situ with microinvasion (DCIS-Mi). MATERIALS AND METHODS: PET/CT images for initial staging of confirmed DCIS and DCIS-Mi patients, taken between July 2004 and December 2009, were reviewed retrospectively. Maximum standardized uptake values (SUVmax) and tumor background count density ratio on PET/CT were compared with tumor characteristics. Histological and biological prognostic factors included tumor size, nuclear grade, Van Nuys Prognostic Index, estrogen receptor, progesterone receptor, HER2, and Ki-67 index. RESULTS: In total, 87 lesions from 83 patients (all females; mean age 51 ± 9 years) were studied. The Van Nuys Prognostic Index group was 1 in 25 lesions, 2 in 36, and 3 in 26. On statistical analysis, significant differences in SUVmax and tumor background count density ratio were seen between the Van Nuys Prognostic Index groups and according to tumor size and HER2. The correlation between SUVmax and Ki-67 was significant. However, the correlation between tumor background count density ratio and Ki-67 was not statistically significant. CONCLUSION: In DCIS and DCIS-Mi cases, significant correlations were found between increased FDG uptake and several histological and biological factors for poor prognosis (tumor size, Van Nuys Prognostic Index, and HER2).

Clinical significance of FDG-PET/CT at the postoperative surveillance in the breast cancer patients.

AIM: We evaluated the clinical role of [(18)F]-2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) compared with conventional imaging (CI) to detect locoregional recurrence or distant metastasis during postoperative surveillance of patients with breast cancer. MATERIALS AND METHODS: We included 1,819 examinations of 1,161 patients, who underwent FDG-PET/CT and CI, including mammography, breast ultrasound, whole-body bone scintigraphy, and chest radiography for postoperative surveillance. All patients had a history of surgery with or without adjuvant treatment due to more than stage II breast cancer between November 2003 and November 2009. We evaluated the diagnostic performance of CI, FDG-PET/CT, and combined CI and FDG-PET/CT for detecting locoregional recurrence, distant metastasis, and incidental cancer. We also analyzed false-positive and false-negative results in both FDG-PET/CT and CI. RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value of CI were 75.4, 98.7, 93.4, and 94.3 %. Those of FDG-PET/CT were 97.5, 98.8, 95.4, and 99.4 %. Those of the combined results were 98.6, 98.2, 96.7, and 99.7 %. Sensitivity of FDG-PET/CT was significantly higher than that of CI (P < 0.05). Sensitivity of combined CI and FDG-PET/CT results improved, but they were not significantly different from those of FDG-PET/CT alone (P = 0.43). Seventeen false-positive and nine false-negative cases were detected with FDG-PET/CT, and 19 false-positive and 88 false-negative cases were detected with CI. CONCLUSION: FDG-PET/CT is considered as an acceptable diagnostic imaging modality for postoperative surveillance of patients with breast cancer.

Correlation of Consecutive Serum Thyroglobulin Levels During Hormone Withdrawal and Failure of Initial Radioiodine Ablation in Thyroid Cancer Patients.

OBJECTIVE: The aim of this study was to evaluate the value of thyroglobulin (Tg) kinetics during preparation of radioiodine ablation for prediction of initial radioiodine ablation failure in thyroid cancer patients. METHODS: Thyroid cancer patients after total thyroidectomy who underwent radioiodine ablation with 3-4 weeks of hormone withdrawal between May 2011 and January 2012 were included. Consecutive serum Tg levels 5-10 days before ablation (Tg1) and on the day of ablation (Tg2) were obtained. The difference between Tg1 and Tg2 (ΔTg), daily change rate of Tg (ΔTg/day) and Tg doubling time (Tg-DT) were calculated. Success of initial ablation was determined by the results of the follow-up ultrasonography, diagnostic radioiodine scan and stimulated Tg level after 6 to 20 months. RESULTS: A total of 143 patients were included. Failed ablation was reported in 52 patients. Tg2 higher than 5.6 ng/ml and Tg-DT shorter than 4.2 days were significantly related to a high risk of ablation failure. ΔTg and ΔTg/day did not show significant correlation with ablation failure. CONCLUSIONS: Thyroglobulin kinetics on consecutive blood sampling during hormone withdrawal may be helpful in predicting patients with higher risk of treatment failure of initial radioiodine ablation therapy in thyroid cancer patients.

Effectiveness of Breast MRI and (18)F-FDG PET/CT for the Preoperative Staging of Invasive Lobular Carcinoma versus Ductal Carcinoma.

PURPOSE: We evaluated the utility of magnetic resonance imaging (MRI) and (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for the preoperative staging of invasive lobular carcinoma (ILC) of the breast and compared the results with those of invasive ductal carcinoma (IDC). METHODS: The study included pathologically proven 32 ILCs and 73 IDCs. We compared clinical and histopathological characteristics and the diagnostic performances of MRI and (18)F-FDG PET/CT for the primary mass, additional ipsilateral and/or contralateral lesion(s), and axillary lymph node metastasis between the ILC and IDC groups. RESULTS: Primary ILCs were greater in size, but demonstrated lower maximum standardized uptake values than IDCs. All primary masses were detected on MRI. The detection rate for ILCs (75.0%) was lower than that for IDCs (83.6%) on (18)F-FDG PET/CT, but the difference was not significant. For additional ipsilateral lesion(s), the sensitivities and specificities of MRI were 87.5% and 58.3% for ILC and 100.0% and 66.7% for IDC, respectively; whereas the sensitivities and specificities of (18)F-FDG PET/CT were 0% and 91.7% for ILC and 37.5% and 94.7% for IDC, respectively. The sensitivity of (18)F-FDG PET/CT for ipsilateral lesion(s) was significantly lower in the ILC group than the IDC group. The sensitivity for ipsilateral lesion(s) was significantly higher with MRI; however, specificity was higher with (18)F-FDG PET/CT in both tumor groups. There was no significant difference in the diagnostic performance for additional contralateral lesion(s) or axillary lymph node metastasis on MRI or (18)F-FDG PET/CT for ILC versus IDC. CONCLUSION: The MRI and (18)F-FDG PET/CT detection rates for the primary cancer do not differ between the ILC and IDC groups. Although (18)F-FDG PET/CT demonstrates lower sensitivity for primary and additional ipsilateral lesions, it shows higher specificity for additional ipsilateral lesions, and could play a complementary role in the staging of ILC as well as IDC.

Clinical significance of diffuse intrathoracic uptake on post-therapy I-131 scans in thyroid cancer patients.

PURPOSE: The purpose of this study was to identify the frequency and possible cause of diffuse intrathoracic uptake on post-therapy I-131 scans in thyroid cancer patients. METHODS: We retrospectively reviewed 781 post-therapy scans of 755 thyroid cancer patients who underwent total thyroidectomy and radioactive iodine therapy between January and December 2010. Diffuse intrathoracic uptake on post-therapy scans was examined, and clinical patient characteristics including sex, age, regimen for thyroid-stimulating hormone (TSH) stimulation (thyroid hormone withdrawal or recombinant human TSH injection), TSH, thyroglobulin (Tg) and anti-thyroglobulin antibody (anti-Tg Ab) levels, therapeutic dose of radioactive iodine therapy and prior history of radioactive iodine therapy were recorded.Scan findings were correlated with chest CT, chest radiographs, laboratory tests and/or clinical status. Diffuse intrathoracic uptake without evidence of pathologic condition was categorized as indeterminate. The association between clinical characteristics and intrathoracic uptake were analyzed for negative intrathoracic uptake and indeterminate uptake groups. RESULTS: Diffuse intrathoracic uptake on post-therapy scans was demonstrated in 39 out of 755 (5.2 %) patients, among which 3 were confirmed as lung metastasis. The 14 patients that showed high Tg or anti-Tg Ab levels were considered to be at risk of having undetected micrometastasis on other imaging modalities. The remaining 22 were indeterminate (2.9 %).Upon comparison of negative intrathoracic uptake and indeterminate uptake groups, TSH stimulation by thyroid hormone withdrawal was shown to be significantly correlated with diffuse intrathoracic uptake (p < 0.05). CONCLUSION: The frequency of diffuse intrathoracic uptake on post-therapy scans was 5.2 % and could be seen in thyroid cancer patients with underlying lung metastasis as well as those without definite pathologic condition. In the latter, there was a higher frequency for diffusely increased intrathoracic uptake in those who underwent thyroid hormone withdrawal rather than recombinant human TSH injection.

The success rate of initial (131)i ablation in differentiated thyroid cancer: comparison between less strict and very strict low iodine diets.

PURPOSE: To decrease the risk of recurrence or metastasis in differentiated thyroid cancer (DTC), selected patients receive radioactive iodine ablation of remnant thyroid tissue or tumor. A low iodine diet can enhance uptake of radioactive iodine. We compared the success rates of radioactive iodine ablation therapy in patients who followed two different low iodine diets (LIDs). MATERIALS AND METHODS: The success rates of postsurgical radioactive iodine ablation in DTC patients receiving empiric doses of 150 mCi were retrospectively reviewed. First-time radioactive iodine ablation therapy was done in 71 patients following less strict LID and 90 patients following very strict LID. Less strict LID restricted seafood, iodized salt, egg yolk, dairy products, processed meat, instant prepared meals, and multi-vitamins. Very strict LID additionally restricted rice, freshwater fish, spinach, and soybean products. Radioactive iodine ablation therapy was considered successful when follow-up (123)I whole body scan was negative and stimulated serum thyroglobulin level was less than 2.0 ng/mL. RESULTS: The success rate of patients following less strict LID was 80.3% and for very strict LID 75.6%. There was no statistically significant difference in the success rates between the two LID groups (p = 0.48). CONCLUSIONS: Very strict LID may not contribute to improving the success rate of initial radioactive iodine ablation therapy at the cost of great inconvenience to the patient.

Clinical Significance of F-18 FP-CIT Dual Time Point PET Imaging in Idiopathic Parkinson's Disease.

PURPOSE: The purpose of this study was to investigate the diagnostic value of dual time point F-18 FP-CIT PET imaging in idiopathic Parkinson's disease (PD). MATERIALS AND METHODS: Twenty-four patients with PD (mean age 69.6) and 18 healthy people (mean age 70.26) underwent two sequential PET/CT scans (dual time point imaging) at 90 and 210 min after F-18 FP-CIT injection. Tracer activity of region of interest was measured in the caudate, putamen and a reference region in the brain from both time points. The outcome parameter was the striatooccipital ratio (SOR). Normal SOR values were obtained in the control group. The percent change in tracer activity between 90- and 210-min images was calculated. The SOR values and the percent change in tracer activity were compared between the patients and healthy control group. RESULTS: The SOR values for the caudate, anterior and posterior putamen at both 90- and 210-min images were significantly reduced in the patients with PD. The lowest P value was obtained for the anterior and posterior putamen (p < 0.001) at both time points. There were significant differences of the percent change in tracer activity for the anterior and posterior putamen in the two groups (p = 0.01). CONCLUSIONS: F-18 FP-CIT PET scans at 90 and 210 min after injection are both able to diagnose PD. Therefore, the 90-min image by itself is sufficient for diagnosing PD.

Whole-Body Bone Scan Findings after High-Intensity Focused Ultrasound (HIFU) Treatment.

PURPOSE: This study aims to examine the findings of (99m)Tc-diphosphonate bone scans in cancer patients with a history of HIFU treatment. METHODS: Bone scan images of patients with a history of HIFU treatment for primary or metastatic cancer from January 2006 to July 2010 were retrospectively reviewed. Cases of primary bone tumor or HIFU treatment reaching only the superficial soft tissue layer were excluded. RESULTS: Bone scan images of 62 patients (26 female, 36 male; mean age 57 ± 9 years) were studied. HIFU treatment was performed in the liver (n = 40), pancreas (n = 16), and breast (n = 6). Mean interval time between HIFU treatment and bone scan was 106 ± 105 days (range: 1-572 days). Of 62 scans, 43 showed diffusely decreased uptake of bone within the path of HIFU treatment: antero-axillary and/or posterior arcs of right 5th to 11th ribs in 34 cases after treatment of hepatic lesions; anterior arcs of 2nd to 5th ribs in 5 cases after treatment for breast tumors; and posterior arcs of left 9th to 11th ribs or thoraco-lumbar vertebrae in 4 cases after treatment for pancreas tumor. Of 20 patients who had bone scans more than twice, five showed recovered uptake of the radiotracer in the involved ribs in the follow-up bone scan. CONCLUSION: Of 62 bone scans in patients with a history of HIFU treatment for primary or metastatic cancer, 69% presented diffusely decreased uptake in the bone in the path of HIFU treatment.