I-131 uptake in a thymic cyst

A 61-year-old woman after total thyroidectomy for papillary thyroid cancer underwent I-131 therapy. Focal uptake was seen in the chest on whole body imaging. SPECT/CT delineated I-131 accumulation in an isodense mediastinal lesion which was histologically diagnosed as a thymic cyst. I-131 uptake in a thymic cyst is rare and should be included in the gamut of false-positive entities of I-131 scintigraphy. Copyright © 2010 by Lippincott Williams & Wilkins

Early prediction of histopathological tumor response to preoperative chemotherapy by Tc-99m MIBI imaging in bone and soft tissue sarcomas

金沢大学附属病院核医学診療科PURPOSE: Tc-99m-methoxyisobutylisonitrile (MIBI) accumulates in only viable cells. In patients with bone and soft tissue sarcomas, preoperative chemotherapy is essential and the early prediction of the tumor response to chemotherapy would be beneficial for the planning of treatment strategy. The purpose of this study was to assess whether the change of Tc-99m-MIBI images from the prechemotherapy state to the early to midportion of chemotherapy can predict the final histopathological tumor response as accurately as the change of imaging after completion of chemotherapy. METHODS: Seventy-three patients with bone and soft tissue sarcomas underwent Tc-99m-MIBI scintigraphy before chemotherapy and at least 2 times after the second or third or fifth course of chemotherapy. The changes of the tracer uptake (ΔUR) and perfusion (ΔPI) from prechemotherapy to postchemotherapy were compared with histologic response. RESULTS: The sensitivity, specificity, and accuracy for the prediction of effective chemotherapy in ΔPI were 88%, 83%, 85% after second, 85%, 72%, 78% after third, and 81%, 71%, 76% after 5th chemotherapy, and those in ΔUR were 88%, 83%, 85% after 2nd, 85%, 92%, 89% after 3rd, and 94%, 77%, 85% after fifth chemotherapy, respectively. The area under the receiver operator characteristic curve of the ΔPI after second, third, and fifth chemotherapy were similarly good (0.842, 0.858, 0.811, respectively) and those of ΔUR were similarly excellent (0.915, 0.936, 0.931, respectively). CONCLUSION: In patients with bone and soft tissue sarcomas, the change of Tc-99m-MIBI images from prechemotherapy to early to middle of chemotherapy can predict the final histopathological tumor response to chemotherapy as accurately as the change of Tc-99m-MIBI images from prechemotherapy to the completion of the preoperative chemotherapy. © 2010 by Lippincott Williams & Wilkins

Esophageal transit study using a sliding sum image: application to patients with probable and definite systemic sclerosis

金沢大学医薬保健研究域医学系Purpose: Esophageal complication is common in systemic sclerosis (SSc), but scintigraphic transit patterns based on each subtype have not been understood well. The aim of this study was to develop a new algorithm for integrating a dynamic esophageal transit study and to apply the method to patients with SSc. Methods: A total of 40 patients suspected of having SSc were examined by a dynamic esophageal transit study. The subtypes included 32 with definite SSc (15 limited cutaneous type and 17 diffuse cutaneous type) and 8 with probable SSc. The serial esophageal images were shifted and summed to a functional image (sliding sum image) and compared to a conventional condensed image analysis. Esophageal retention fraction at 90 s (R90) and half-time (T1/2) of transit were also measured. Results: The four patterns of the sliding sum image and condensed image agreed in all patients. Abnormal retention patterns were observed in none of the 8 (0%) patients with the probable SSc and in 15 of 32 (47%) patients with definite SSc (p = 0.014). The severity of scleroderma assessed by modified Rodnan skin thickness score correlated with that of esophageal retention R90 (p = 0.04). Conclusion: The sliding sum image is a simple and effective method for integrating esophageal transit. Patients with definite SSc and severe scleroderma had significantly higher retention patterns, while probable SSc patients showed no esophageal dysmotility. © 2011 The Japanese Society of Nuclear Medicine

Prognostic value of Tc-99m-MIBI performed during middle course of preoperative chemotherapy in patients with malignant bone and soft-tissue tumors

Purpose: This study was aimed to determine whether Tc-99m-hexakis-2- methoxyisobutylisonitrile (MIBI) scintigraphy performed in the middle of preoperative chemotherapy has a prognostic value in patients with malignant bone and soft tissue tumors (MBST). Materials and Methods: In 90 patients with MBST, Tc-99m-MIBI scintigraphy was performed 15 minutes after tracer injection before the first and after the third chemotherapy cycles. After 5 cycles of chemotherapy and tumor resection, therapeutic effect was assessed by histopathology. The percent reduction of uptake ratio (AUR) was calculated according to the following equation: 100 × ([prechemotherapy UR - post-middle course of chemotherapy UR]/prechemotherapy UR). Results: The average follow-up for the entire population was 52 months. Twenty-one patients had clinically detectable metastases at initial presentation (primary metastasis). Kaplan-Meier analysis demonstrated that absence of metastasis was associated with good survival in all patients, in patients with bone tumor, and those with soft tissue tumor (P < 0.0001, P < 0.0001, and P = 0.0003, respectively), and AUR ≥30% was also associated with survival in all patients and patients with bone tumor (P = 0.011 and P = 0.047, respectively), but was marginal in those with soft tissue tumor (P = 0.091). Multivariate analysis showed that primary metastasis was the most powerful independent predictor of a lethal clinical outcome in all patients, in both patients with bone and soft tissue tumors (hazard ratio [HR]: 4.9, 95% confidence interval [CI]: 2.61-9.08, P < 0.0001; HR: 15.1, CI: 4.86-52.7, P < 0.0001; HR: 3.7, CI: 1.45-8.94, P = 0.0069, respectively) and showed that Tc-99m-MIBI scintigraphy had a good independent long-term prognostic value in all patients and patients with bone tumor (HR: 2.2, CI: 1.14-4.43, P = 0.017; HR: 6.0, CI: 2.01-21.6, P = 0.0009, respectively) but not in those with soft tissue tumor (HR: 1.5, CI: 0.61-4.09, P = 0.38). Good disease-free survival was associated with ΔUR §30% in all patients and patients with soft tissue tumor (P = 0.0093 and P = 0.017, respectively) but not in those with bone tumor (P = 0.19). Conclusions: Tc-99m-MIBI scintigraphy at the middle course of preoperative chemotherapy could be used as a prognostic indicator in patients with MBST. Copyright © 2012 by Lippincott Williams & Wilkins.Thesis of Hiroshi Wakabayashi / 博士学位論文 若林 大

Low-dose 123I-metaiodobenzylguanidine diagnostic scan is inferior to 131I-metaiodobenzylguanidine posttreatment scan in detection of malignant pheochromocytoma and paraganglioma

OBJECTIVE: We assessed the lesion detectability of low-dose diagnostic 123I-metaiodobenzylguanidine (MIBG) whole-body scans obtained at 6 and 24 h compared with posttreatment 131I-MIBG whole-body scans in malignant pheochromocytoma and paraganglioma. METHODS: Scintigrams obtained in 15 patients with malignant pheochromocytoma and paraganglioma were retrospectively analyzed. Diagnostic scans were performed with 111 MBq of 123I-MIBG. Therapeutic doses of 131I-MIBG (5.55-7.40 GBq) were administrated and whole-body scans were obtained at 2-5 days after 123I-MIBG administrations. We compared the number of lesions and the lesion-to-referent count ratios at 6 and 24 h of 123I-MIBG and at 2-5 days of 131I-MIBG. RESULTS: In comparison with the 6-h images of 123I-MIBG, the 24-h images of 123I-MIBG could detect more lesions in eight patients. Posttreatment 131I-MIBG scans revealed new lesions in eight patients compared with the 24-h images of 123I- MIBG. The lesion-to-referent count ratios at 6 and 24 h of 131I-MIBG and at 3 days of 131I-MIBG were increasing at later scanning time. There were significant differences in the lesion-to-referent count ratios between 6 and 24 h of 123I-MIBG (P=0.031), 6 h of 131I-MIBG and 3 days of 123I-MIBG (P=0.020), and 24 h of 123I-MIBG and 3 days of 131I-MIBG (P=0.018). CONCLUSION: Low-dose diagnostic 123I-MIBG whole-body scan is inferior to posttreatment 131I-MIBG whole-body scan in malignant pheochromocytoma and paraganglioma. Considering the scan timing of 123I-MIBG, 6-h images might have no superiority compared with 24-h images. © 2011 Wolters Kluwer Health | Lippincott Williams &Wilkins

Esophageal transit scintigraphy and structured questionnaire in patients with systemic sclerosis with endoscopically proven reflux esophagitis

金沢大学医薬保健研究域医学系Objectives: Esophageal complications are common in patients with systemic sclerosis (SSc). The relationship between gastroesophageal reflux (GER) symptoms and dysmotility was examined in endoscopically confirmed patients suspected of having reflux esophagitis. Methods: A total of 32 patients with limited and diffuse type SSc (lSSc, dSSc) were examined based on a structured questionnaire score (QS) of GER symptoms, retention fraction of esophageal scintigraphy at 90 s (R90) and gastric emptying time. Results: The QS was significantly higher in the reflux esophagitis group than in the non-esophagitis group (5.4 ± 3.5, 1.4 ± 2.9, P = 0.003). When the non-esophagitis group was further divided into lSSc and dSSc groups, R90 was higher in the reflux esophagitis group (31 ± 18%) and the non-esophagitis group with dSSc (34 ± 32%) than in the non-esophagitis group with lSSc (8 ± 3%, P = 0.02). Both high R90 ≥ 15% and QS ≥ 4 indicated reflux esophagitis. Conversely, both normal R90 and QS indicated no reflux esophagitis. Conclusion: A combination of esophageal scintigraphy and structured questionnaire demonstrated different aspects of esophageal dysfunction, namely dysmotility and GER. Patients with high QS and dysmotility may be indicated for further evaluation including endoscopic examination and medical treatment. © 2009 The Japanese Society of Nuclear Medicine