Thyroid remnant ablation using 1,110 MBq of I-131 after total thyroidectomy: regulatory considerations on release of patients after unsealed radioiodine therapy.

OBJECTIVES: This study was undertaken to measure the radiation exposure level of caregivers following outpatient NaI (I-131) 1,110 MBq therapy for remnant thyroid ablation after total thyroidectomy in patients with differentiated thyroid cancer, and to evaluate the influence of activities of daily living on radiation exposure level, with the goal of proposing an optimum method of I-131 therapy. METHODS: The study included 37 patients with differentiated thyroid cancer, who had undergone total thyroidectomy and received outpatient based remnant thyroid ablation using NaI (I-131) 1,110 MBq, who were satisfying the following requirements: (1) patients who have no evidence of distant metastases, (2) whose living environments were appropriate for outpatient I-131 (1,110 MBq) therapy, and (3) patients who gave written informed consent. The dose rate at a distance of 1 m from the body surface of the patient at the moment of release was measured using survey meters of the GM type or ionization chamber type. The dose level for the caregiver was measured with a personal dosimeter in all cases. RESULTS: The dose rate at a distance of 1 m from the patient's body surface 1 h after I-131 administration was in the range of 29-115 µSv/h (mean 63.8 µSv/h). The 7-day cumulative effective dose of caregivers was 0.11 ± 0.08 mSv, on an average, in 34 dosimeters. In 31 of 34 dosimeters, cumulative effective dose of caregivers was below 0.2 mSv. Dose levels exceeding 0.2 mSv were recorded in 3 cases (0.21, 0.35 and 0.43 mSv in one case each). These results suggest that the exposure level of family members (caregiver and others) was minimal and is lower than the radiation levels affecting human environments. CONCLUSION: Outpatient-based remnant thyroid ablation with I-131 (1,110 MBq) performed after total thyroidectomy in patients with differentiated thyroid cancer is safe if applied in accordance with the appropriate supervision and guidance by experts with certain qualifications.

[Usefulness of (18)F-FDG PET/CT for detecting lesions in patients with POEMS syndrome].

Many patients with POEMS syndrome have osteosclerotic plasmacytoma. Radiation therapy is useful for patients who have localized lesions, although chemotherapy is necessary for patients who have widespread lesions. Thus, evaluation of these lesions is important to determine the therapeutic strategy. We evaluated the activities of lesions in two patients with POEMS syndrome by (18)F-FDG positron emission tomography (PET)/computed tomography (CT) scan. In the first patient, PET/CT scan revealed osteosclerotic lesions, which were not detected by Ga-scintigraphy or plain X-ray. It also detected residual disease activity and relapse. In the second patient, lymph node involvement was suggested by (18)F-FDG uptake, and plasmacytoma was confirmed by subsequent biopsy. In the extramedullary lesions of this case, FDG uptake was as marked as in myeloma, whereas bone lesion was only detectable by CT scan. In POEMS syndrome, the PET and CT are complementary, and the combined PET/CT scan is considered to be very useful for evaluation of involved lesions.

Comparison of parameters of (123)I-metaiodobenzylguanidine scintigraphy for differential diagnosis in patients with parkinsonism: correlation with clinical features.

OBJECTIVES: The purpose of this study was to estimate the diagnostic accuracy of (123)I-metaiodobenzylguanidine (MIBG) scintigraphy to diagnose Lewy body disease (LBD), including Parkinson's disease (PD) and dementia with Lewy bodies, and to clarify the relationship between MIBG parameters and the clinical findings. METHODS: One hundred-and-forty-four patients with parkinsonism without diabetes mellitus or a history of cardiac disease were retrospectively selected in the study. Clinical diagnosis was confirmed by follow-up during more than 6 months by neurologists. All patients underwent MIBG imaging at 15 min (initial) and 4 h (delayed) after the tracer injection, and clinical features such as Hoehn and Yahr (H-Y) classification or symptoms specific to parkinsonism were also investigated. The heart to mediastinum ratio (H/M) and the washout ratio (WR) of MIBG were calculated, and correlation with the clinical features was analyzed. RESULTS: Ninety-seven and 47 patients were diagnosed as LBD and Parkinson's syndrome (PS), respectively. Initial and delayed H/M were significantly lower and WR was significantly higher in LBD than in PS (p < 0.0001). The initial H/M was independently correlated with tremor (F value 10.45), hesitation (F = 4.49), and hallucinations (F = 5.09) (p < 0.0001). The sensitivity and specificity for the diagnosis of LBD were 64.9 and 87.2% with initial H/M, 78.4 and 68.1% with delayed H/M, and 80.4 and 61.7% with WR, respectively. Using multivariate analysis, initial H/M (F = 39.33) and tremor (F = 10.46) were independently correlated to the diagnosis of LBD (r = 0.562, p < 0.0001) among the MIBG and various clinical parameters. CONCLUSION: The initial H/M was the most useful of the 3 different parameters of MIBG for the diagnosis of LBD, but had low sensitivity. WR and delayed H/M had no incremental value to initial H/M for the diagnosis of PD. Careful long-term follow-up is needed for patients with parkinsonism who are clinically diagnosed as LBD with normal initial H/M, or diagnosed as no LBD with low initial H/M.

Myocardial 99mTc-sestamibi extraction and washout in hypertensive heart failure using an isolated rat heart.

PURPOSE: Myocardial mitochondria are the primary part of energy production for healthy cardiac contraction. And mitochondrial dysfunction would play an important role in progressive heart failure. In the recent years, myocardial washout of (99m)Tc-sestamibi [((99m)Tc-hexakis-2-methoxy-2-methylpropyl isonitrile (MIBI)] has been introduced to be a potential marker in patients with heart failure. The objective of this study was to clarify MIBI extraction and washout kinetics using isolated perfusion system in hypertension induced model of myocardial dysfunction. METHODS: Six-week-old Dahl-salt sensitive rats, allotted to 4 groups; a 5-week high-salt group (5 wk-HS), 12-week high-salt group (12 wk-HS) and two age-matched, low-salt diet control groups (5 wk-LS and 12 wk-LS). The rats in 5 wk-HS and 12 wk-HS groups were fed a high-salt diet (containing 8% NaCl). Cardiac function was examined by echocardiography before removing heart. Hearts were perfused according to the Langendorff method at a constant flow rate, in which 20-min MIBI washin was conducted followed by 25-min MIBI washout. Whole heart radioactivity was collected every sec by an external gamma detector. The myocardial extraction, K(1) (ml/min) and washout rate, k(2) (min(-1)) were generated. RESULTS: High-salt diet groups showed significant high-blood pressure. Echocardiography revealed thickened LV walls in 5 wk-HS, and reduced cardiac function in 12 wk-HS, compared to each age-matched control group. K(1) showed no significant difference among all groups (5 wk-HS: 2.36 ± 1.07, 5 wk-control: 2.59 ± 0.28, 12 wk-HS: 1.91 ± 0.90, and 12 wk-control: 2.84 ± 0.57). k(2) in 5 wk-HS was comparable to that in the age matched control group (0.00030 ± 0.00039 vs -0.000010 ± 0.00044), but it was increased remarkably in 18 wk-HS compared to the age matched control group (0.0025 ± 0.0011 vs 0.000025 ± 0.000041, P<.01), and 5 wk-HS (P<.01). CONCLUSION: In the course of hypertensive heart disease, MIBI washout was increased in the transitional state from hypertrophied to dilated and failing heart, while MIBI extraction remained intact.

Ability of 18F-FDG PET/CT to diagnose recurrent colorectal cancer in patients with elevated CEA concentrations.

OBJECTIVE: Elevated levels of serum carcinoembryonic antigen (CEA) in patients with colorectal cancer (CRC) during follow-up suggest recurrence, which can be visualized by (18)F-FDG PET/CT. Since the magnitude of CEA elevation reflects cancer volume, the ability of PET/CT to detect recurrence in patients with only mildly elevated CEA might be limited. However, the accuracy of PET/CT in detecting recurrence associated with elevated CEA has not been fully assessed. We retrospectively evaluated the diagnostic performance of (18)F-FDG PET/CT postoperatively relative to CEA levels among patients with CRC. METHODS: We visually assessed 75 PET/CT evaluations of 57 postoperative patients with CEA >5.0 ng/ml. Tumor volumes were also determined using image analysis software. The final diagnosis was confirmed based on histopathological findings, or at least on 6 months of clinical follow-up. RESULTS: Two lung cancers were excluded and we finally analyzed data from 73 of the 75 PET/CT evaluations. Recurrences were diagnosed in 54 (prevalence 74%). The sensitivity and specificity of PET/CT to detect recurrence was 50/54 (93%) and 14/19 (74%), respectively. The positive and negative predictive values were 91 and 78%, respectively, and the positive and negative likelihood ratios were 3.52 and 0.10, respectively. Values for the sensitivity of PET/CT were 88 and 95%, and those for specificity were 78 and 70%, at serum CEA concentrations of 5-10 and >10 ng/ml, respectively. Serum CEA (r = 0.500, p < 0.001) significantly correlated with cancer volumes. CONCLUSIONS: The present findings showed that (18)F-FDG PET/CT could accurately detect recurrent CRC irrespective of the elevated CEA concentration.

[Assessment of the efficacy, safety and pharmacokinetics of SKG-02 (recombinant human TSH) in postoperative diagnosis of well-differentiated thyroid cancer--a Japanese prospective, controlled, multicenter open-label study].

OBJECTIVE: This study sought to assess the safety, efficacy, impact on hypothyroid symptoms, and pharmacokinetics of SKG-02 (rhTSH, thyrotropin alfa) in the diagnostic follow-up of Japanese patients with well-differentiated thyroid carcinoma (WDTC). METHODS: Ten Japanese adults with WDTC were enrolled into a prospective, multicenter, open-label trial comparing diagnostic whole-body scintigraphy (dxWBS) and serum thyroglobulin (Tg) testing aided by SKG-02 versus these procedures aided by thyroid hormone withdrawal (THW). Patients were their own controls. Variables compared included scan set ability to detect radioiodine uptake by remnant or malignant thyroid tissue, scan set quality, diagnostic sensitivity of dxWBS and Tg testing alone or combined, frequency of hypothyroid signs/symptoms, and adverse events (AEs). SKG-02 pharmacokinetic variables including maximum concentration (Cmax), time to Cmax (Tmax) and the area under the time-concentration curve (AUC) were calculated. RESULTS: In a blinded evaluation by an independent committee of 3 nuclear medicine experts, 70% of SKG-02 dxWBS scan sets were rated "equivalent" (n = 7) or "superior" (n = 0) to their THW counterparts in ability to detect radioiodine uptake in healthy or malignant thyroid tissue. Therefore the study exceeded its primary endpoint of a 60% equivalence/superiority rate. SKG-02 Tg testing identified 3/3 cases of disease. Hypothyroid signs/symptoms were substantially more frequent during THW than during euthyroidism permitted by SKG-02 use. SKG-02 was well-tolerated, with no severe or serious drug-related AEs. Cmax was 240.8 +/- 65.9 microIU/ml, Tmax was 28.75 +/- 14.21 hr after the first SKG-02 injection, and AUC was 11,414 +/- 3,462 microIU hr/ml in 9 patients evaluable for pharmacokinetics. CONCLUSIONS: SKG-02 was safe and effective in the diagnostic follow-up of Japanese patients with WDTC, avoiding hypothyroid morbidity relative to THW. These and the pharmacokinetic findings were similar to those of overseas Phase III studies.

Ability of 201Tl and 123I-BMIPP mismatch to diagnose myocardial ischemia in patients with suspected coronary artery disease.

OBJECTIVE: A mismatch defect between (201)TL and (123)I-BMIPP dual isotope SPECT (d-SPECT) is useful to detect myocardial ischemia in patients with acute coronary syndrome. However, whether mismatched d-SPECT findings reflect actual myocardial ischemia in stable patients with suspected, but unknown ischemic heart disease is unclear. The present study assesses the significance of a d-SPECT mismatch among such patients. METHODS: Forty-nine patients with suspected stable coronary heart disease who had been referred for chest pain, ECG abnormalities or multiple risk factors (66 +/- 11 years old, 34 males) with a d-SPECT mismatch participated in this study. All of them underwent coronary angiography (CAG) to assess coronary artery disease. The entire myocardial area on d-SPECT images was divided into 17 segments, each of which was scored from 0 (normal) to 4 (defect). The d-SPECT mismatch score (MS) was defined as the summed BMIPP defect score (BM-TDS) minus the summed defect score (TL-TDS). The inclusion criterion was MS >or= 1, and the mismatch was defined as true positive if the mismatched area was concordant with the territories supplied by significant coronary stenotic arteries by CAG. RESULTS: Ischemic heart disease was judged by coronary angiography in 31 (63%) patients (IHD group), of which 24 (49.0%) were true positives. Of the remaining 18 (37%) patients without no significant coronary stenosis (non-IHD group), 12 (24%) had some types of organic heart disease. If MS >or= 4 was defined as the threshold for an ischemic positive mismatch, then the sensitivity and specificity were 80% and 63%, respectively. However, mismatch scores did not significantly differ between the groups with true positive-IHD and organic heart disease in non-IHD group (6.6 +/- 4.4 vs. 6.4 +/- 3.7). CONCLUSION: A d-SPECT mismatch score of >or=4 was an appropriate cutoff at which diagnosis of myocardial ischemia in patients who were screened for ischemic heart disease. However, since patients with non-ischemic but organic heart disease can also present with abnormal mismatch findings, coronary angiography or CT might be warranted to differentiate IHD from non-IHD.

Comparison of imaging protocols for 18F-FDG PET/CT in overweight patients: optimizing scan duration versus administered dose.

UNLABELLED: The quality of (18)F-FDG PET/CT images of overweight patients is often degraded. We evaluated the effect of optimizing injected dose or acquisition time on the quality of images of overweight patients using lutetium oxyorthosilicate PET/CT with high-performance detector electronics. METHODS: We initially retrospectively measured radioactivity concentrations and signal-to-noise ratios (SNRs) in the liver relative to body weight for 80 patients who had undergone (18)F-FDG PET/CT according to our standard protocol (injected dose, 3.7 MBq/kg; acquisition time, 2 min/bed position). The patients were grouped (n = 20 per group) according to baseline body weight as G1 (or=85 kg). We compared the SNRs of G1 with those of G2, G3, and G4 and calculated the ratio squared as a factor to correct the acquisition parameters for overweight patients. We then prospectively enrolled 120 patients according to the same body weight criteria. We multiplied the correction factors to optimize injected doses or acquisition times and defined dose-adjusted groups (n = 20 per group) and time-adjusted groups (n = 20 per group). G2 dose was defined as 5.59 +/- 0.19 MBq/kg, G3 dose as 7.29 +/- 0.33 MBq/kg, and G4 dose as 8.88 +/- 0.43 MBq/kg. G2 time was defined as 3 min/bed position, G3 time as 4 min/bed position, and G4 time as 5 min/bed position. RESULTS: Although liver activities did not significantly differ among G1 through G4 irrespective of patient weight, SNR progressively decreased as patient weight increased. The liver activities of G2 dose, G3 dose, and G4 dose were, respectively, 1.4-, 1.9-, and 2.5-fold higher than those of the baseline counterparts. Nevertheless, the increased liver activities of G2 dose, G3 dose, and G4 dose did not significantly affect SNR, compared with the baseline groups. In contrast, the SNR of G4 time was significantly higher than that of G4. CONCLUSION: Our findings suggest that the quality of images acquired from heavier patients can be maintained only by scanning for longer periods. Increasing the dose per kilogram of body weight did not improve the quality of lutetium oxyorthosilicate PET/CT images.

Prognostic significance of stress myocardial ECG-gated perfusion imaging in asymptomatic patients with diabetic chronic kidney disease on initiation of haemodialysis.

PURPOSE: Diabetic patients with chronic kidney disease (CKD) frequently develop cardiac events within several years of the initiation of haemodialysis. The present study assesses the prognostic significance of stress myocardial ECG-gated perfusion imaging (MPI) in patients with diabetic CKD requiring haemodialysis. METHODS: Fifty-five asymptomatic patients with diabetic stage V CKD and no history of heart disease scheduled to start haemodialysis were enrolled in this study (56 +/- 11 years old; 49 with type 2 diabetes mellitus). All patients underwent (201)Tl stress ECG-gated MPI 1 month before or after the initiation of haemodialysis to assess myocardial involvement. We evaluated SPECT images using 17-segment defect scores graded on a 5-point scale, summed stress score (SSS) and summed difference scores (SDS). The patients were followed up for at least 2 years (42 +/- 15 months) to determine coronary intervention (CI) and heart failure (HF) as soft events and acute myocardial infarction (AMI) and all causes of deaths as hard events. RESULTS: The frequencies of myocardial ischaemia, resting perfusion defects, low ejection fraction and left ventricular (LV) dilatation were 24, 20, 29 and 49%, respectively. Ten events (18%) developed during the follow-up period including four CI, one HF, one AMI and four sudden deaths. Multivariate Cox analysis selected SDS (p = 0.0011) and haemoglobin A(1c) (HbA(1c)) (p = 0.0076) as independent prognostic indicators for all events. CONCLUSION: Myocardial ischaemia, in addition to glycaemic control, is a strong prognostic marker for asymptomatic patients with diabetic CKD who are scheduled to start haemodialysis. Stress MPI is highly recommended for the management and therapeutic stratification of such patients.

[The 29th report on survey of the adverse reaction to radiopharmaceuticals (the 32nd survey in 2006)].

This survey was performed in order to investigate the incidence of adverse reactions to radiopharmaceuticals in FY2006 in Japan. It was based on responses to questionnaires sent to nuclear medicine institutions. The reply was obtained from 975 institutions among 1263 to which the questionnaire had been sent. Thirty-two cases of adverse reactions were reported. A total of 1,189,127 radiopharmaceutical administrations was reported. The incidence of adverse reactions per 100,000 cases was 2.7. Three cases of defect products were reported, and the incidence of defect products per 100,000 cases was 0.3.

Prognostic value of 123I-metaiodobenzylguanidine in patients with various heart diseases.

OBJECTIVE: It has been reported that (123)I-metaiodobenzylguanidine (MIBG) scintigraphy can predict the poor prognosis in patients with dilated cardiomyopathy (DCM). However, the prognostic significance of MIBG is still unknown in patients with other heart diseases. In this study, we compared the prognosis and MIBG findings in various heart diseases. METHODS: Consecutive 565 patients undergoing MIBG scintigraphy were enrolled (392 men, 52 +/- 16 years). Indications were that 127 had ischemic heart disease (IHD), 120 DCM, 101 hypertrophic cardiomyopathy (HCM), 21 hypertensive heart disease (HHD), 58 volume-load valvular disease (VVD), 38 pressure-load valvular disease (PVD), and 101 ventricular tachycardia or fibrillation (VTF). Heart-to-mediastinum ratio (H/M) and washout rate (WR) of MIBG were evaluated. Cardiac events were defined as sudden cardiac death, heart failure, and acute ischemic event (follow-up, 22.7 +/- 17.0 months). RESULTS: A total of 106 cardiac events including 40 cardiac deaths occurred. Cox hazard model analysis showed that in the IHD, HCM, and DCM groups, H/M and WR were associated with cardiac death, but not in the HHD, PVD, VVD, or VTF groups. Only death and congestive heart failure (CHF) episodes were related to H/M and WR. On the other hand, fatal arrhythmia, myocardial infarction, or angina pectoris were not related to H/M and WR. The data indicated that WR or H/M may predict death and CHF but does not predict fatal arrhythmia or acute ischemic event. CONCLUSIONS: MIBG WR and H/M were associated with heart failure, sudden death, and cardiac death events, and were useful to predict the prognosis in DCM, HCM, and IHD. In contrast, fatal arrhythmia events were not associated with MIBG indices, and thus it does not appear to be useful in predicting cardiac events in patients with VTF.

Myocardial kinetics of (201)Thallium, (99m)Tc-tetrofosmin, and (99m)Tc-sestamibi in an acute ischemia-reperfusion model using isolated rat heart.

OBJECTIVE: (201)Thallium (TL), (99m)Tc-tetrofosmin (TF), and (99m)Tc-sestamibi (MIBI) are extensively used as myocardial perfusion agents. The objective of the present study was to evaluate their kinetics under acute ischemia-reperfusion. METHODS: Isolated rat hearts, perfused by the Langendorff method at a constant flow rate of 10 ml/min, were allotted to normal control, mild ischemia, and severe ischemia groups, in which 20-min tracer wash-in was conducted followed by a 25-min tracer washout. No-flow ischemia (15 min for mild ischemia groups; 30 min for severe ischemia groups) was induced before conducting wash-in and washout in the ischemia groups. Whole-heart radioactivity was determined with an external gamma detector. Myocardial flow rate (K (1), ml/min) and clearance rate (k (2), min(-1)) were calculated. RESULTS: K (1TL), K (1TF), and K (1MIBI) decreased according to the severity of ischemia (K (1TL) 5.32 +/- 0.53, 4.76 +/- 0.70, and 1.44 +/- 0.59; K (1TF) 3.80 +/- 0.70, 2.73 +/- 0.99, and 1.09 +/- 0.45; and K (1MIBI) 3.45 +/- 1.10, 2.15 +/- 0.82, and 1.05 +/- 0.13, in the normal control, mild, and severe ischemia groups, respectively). K (1) was significantly higher for TL than for the (99m)Tc tracers (P < 0.05), but the (99m)Tc tracers had equivalent K (1) values. k (2TL) increased significantly (P < 0.05) in the ischemia groups (k (2TL) 0.062 +/- 0.013, 0.11 +/- 0.045, and 0.12 +/- 0.035), but showed no significant difference between the ischemia groups. k (2MIBI) and k (2TF) were significantly (P < 0.05) lower than k (2TL) and increased significantly (P < 0.05) in the severe ischemia group (k (2TF) 0.0056 +/- 0.0022, 0.0037 +/- 0.0015, and 0.024 +/- 0.015; and k (2MIBI) 0.00072 +/- 0.0011, 0.00038 +/- 0.00076, and 0.042 +/- 0.034). k (2MIBI) was significantly (P < 0.05) lower than k (2TF) in the normal control and mild ischemia groups. CONCLUSIONS: Tracer extraction was higher for TL than for the (99m)Tc tracers and all tracers decreased according to the severity of ischemia-reperfusion in the three tracer groups. The clearance kinetics of not only MIBI but also TF is possibly useful for the evaluation of the severity of ischemia, and the Langendorff method and a methodological approach by continuous determinations of radioactivity may serve for the quantitative analysis of tracer kinetic profiles.

[The 28th report on survey of the adverse reaction to radiopharmaceuticals (the 31st survey in 2005)].

This survey was performed in order to investigate the incidence of adverse reactions to radiopharmaceuticals in FY2005 in Japan. It was based on responses to questionnaires sent to nuclear medicine institutions. The reply was obtained from 1,007 institutions among 1,243 to which the questionnaire had been sent. Nineteen cases of adverse reactions were reported. A total of 1,264,098 radiopharmaceutical administrations was reported. The incidence of adverse reactions per 100,000 cases was 1.5. Three cases of defect products were reported, and the incidence of defect products per 100,000 cases was 0.2.

[The 27th Report on Survey of the Adverse Reaction to Radiopharmaceuticals (the 30th survey in 2004)].

This survey was performed in order to investigate the incidence of adverse reactions to radiopharmaceuticals and defect products in FY2004 in Japan. It was based on responses to questionnaires sent to nuclear medicine institutions. The reply was obtained from 968 institutions among 1,220 to which the questionnaire had been sent. Sixteen cases of adverse reactions were reported. A total of 1,277,906 radiopharmaceutical administrations was reported. The incidence of adverse reactions per 100,000 cases was 1.3. Eight cases of defect products were reported, and the incidence of defect products per 100,000 cases was 0.6.

Accuracy of PET for diagnosis of solid pulmonary lesions with 18F-FDG uptake below the standardized uptake value of 2.5.

UNLABELLED: Benign and malignant pulmonary lesions usually are differentiated by 18F-FDG PET with a semiquantitative 18F-FDG standardized uptake value (SUV) of 2.5. However, the frequency of malignancies with an SUV of <2.5 is significant, and pulmonary nodules with low 18F-FDG uptake often present diagnostic challenges. METHODS: Among 360 consecutive patients who underwent 18F-FDG PET to evaluate pulmonary nodules found on CT, we retrospectively analyzed 43 who had solid pulmonary lesions (excluding lesions with ground-glass opacity, infiltration, or benign calcification) with an SUV of <2.5. The uptake of 18F-FDG was graded by a visual method (absent, faint, moderate, or intense) and 2 semiquantitative methods (SUV and contrast ratio [CR]). Final classification was based on histopathologic findings or at least 6 mo of clinical follow-up. RESULTS: We found 16 malignant (diameter, 8-32 mm) and 27 benign (7-36 mm) lesions. When faint visual uptake was the cutoff for positive 18F-FDG PET results, the receiver-operating-characteristic (ROC) analysis correctly identified all 16 malignancies and yielded false-positive results for 10 of 27 benign lesions. Sensitivity was 100%, specificity was 63%, and the positive and negative predictive values were 62% and 100%, respectively. When an SUV of 1.59 was the cutoff for positive 18F-FDG PET results, the ROC analysis revealed 81% sensitivity, 85% specificity, and positive and negative predictive values of 77% and 89%, respectively. At a cutoff for positive 18F-FDG PET results of a CR of 0.29, the ROC analysis revealed 75% sensitivity, 82% specificity, and positive and negative predictive values of 71% and 85%, respectively. The areas under the curve in ROC analyses did not differ significantly among the 3 analyses (visual, 0.84; SUV, 0.81; and CR, 0.82). Analyses of intra- and interobserver variabilities indicated that visual and SUV analyses were quite reproducible, whereas CR analysis was poorly reproducible. CONCLUSION: These results suggested that for solid pulmonary lesions with low 18F-FDG uptake, semiquantitative approaches do not improve the accuracy of 18F-FDG PET over that obtained with visual analysis. Pulmonary lesions with visually absent uptake indicate that the probability of malignancies is very low. In contrast, the probability of malignancy in any visually evident lesion is about 60%.

Real-time volumetric imaging of human heart without electrocardiographic gating by 256-detector row computed tomography: initial experience.

OBJECTIVE: The feasibility of human cardiac imaging using a prototype 256-detector row cone-beam computed tomography (256CBCT) scanner without electrocardiographic gating was examined. METHODS: Two healthy male volunteers were examined by contrast-enhanced 256CBCT. The number of detectors was 912 x 256, each measuring approximately 0.5 mm x 0.5 mm at the center of rotation. The craniocaudal coverage was approximately 100 mm after reconstruction by the Feldkamp-Davis-Kress algorithm. The effective time resolution was 500 milliseconds using a half-scan algorithm. RESULTS: Serial enhancement of the left ventricular myocardium was detected. The right and left coronary arteries at proximal and distal segments were depicted without significant blurring. Although the left ventricular wall motion on cine images was not smooth over time, it was possible to measure ventricular volume and ejection fraction. CONCLUSIONS: Using the 256CBCT, it was possible to visualize the coronary arteries, myocardial perfusion, and ventricular contraction simultaneously during a single acquisition.

Probability of axillary lymph node metastasis when sentinel lymph node biopsy is negative in women with clinically node negative breast cancer: a Bayesian approach.

BACKGROUND: Although sentinel lymph node biopsy(SLNB)is highly accurate in predicting axillary nodal status in patients with breast cancer, it has been shown that the procedure is associated with a few false negative results. The risk of leaving metastatic nodes behind in the axillary basin when SLNB is negative should be estimated for an individual patient if SLNB is performed to avoid conventional axillary lymph node dissection(ALND). METHODS: A retrospective analysis of 512 women with T1-3N0M0 breast cancer was conducted to derive a prevalence of nodal metastasis by T category as a pre-test(i.e., before SLNB)probability and to examine potential confounders on the relationship between T category and axillary nodal involvement. Probability of nodal metastasis when SLNB was negative was estimated by means of Bayes' theorem which incorporated the pre-test probability and sensitivity and specificity of SLNB. RESULTS: Axillary nodal metastasis was observed in 6.1% of T1a-b, 25.1% of T1c, 28.7% of T2, 35.0% of T3 tumors. Point estimates for the probability of nodal involvement when SLNB was negative ranged from 0.3-1.3% for T1a-b, 1.6-6.3% for T1c, 2.0-7.5% for T2, and 2.6-9.7% for T3 tumors with representative sensitivities of 80%, 85%, 90% and 95%, respectively. The risk may be higher when the tumor involves the upper outer quadrant of the breast, while it may be lower for an underweight woman. CONCLUSIONS: The probability of axillary lymph node metastasis when SLNB is negative can be estimated using a Bayesian approach. Presenting the probability to the patient may guide the decision of surgery without conventional ALND.