Time efficient 124I-PET volumetry in benign thyroid disorders by automatic isocontour procedures: mathematic adjustment using manual contoured measurements in low-dose CT
Abstract
Background
Benign thyroid diseases are widely common in western societies. However, the volumetry of the thyroid gland, especially when enlarged or abnormally formed, proves to be a challenge in clinical routine. The aim of this study was to develop a simple and rapid threshold-based isocontour extraction method for thyroid volumetry from 124I-PET/CT data in patients scheduled for radioactive iodine therapy.
Methods
PET/CT data from 45 patients were analysed 30 h after 1 MBq 124I administration. Anatomical reference volume was calculated using manually contoured data from low-dose CT images of the neck (MC). In addition, we applied an automatic isocontour extraction method (IC0.2/1.0), with two different threshold values (0.2 and 1.0 kBq/ml), for volumetry of the PET data-set. IC0.2/1.0 shape data that showed significant variation from MC data were excluded. Subsequently, a mathematical correlation using a model of linear regression with multiple variables and step-wise elimination (mIC0.2/1.0), between IC0.2/1.0 and MC, was established.
Results
Data from 41 patients (IC0.2), and 32 patients (IC1.0) were analysed. The mathematically calculated volume, mIC, showed a median deviation from the reference (MC), of ±9 % (1–54 %) for mIC0.2 and of ±8.2 % (1–50 %) for mIC1.0
Conclusion
Contour extraction with both, mIC1.0 and mIC0.2 gave rapid and reliable results. However, mIC0.2 can be applied to significantly more patients (>90 %) and is, therefore, deemed to be more suitable for clinical routine, keeping in mind the potential advantages of using 124I-PET/CT for the preparation of patients scheduled for radioactive iodine therapy.
The preliminary study of 18F-FLT micro-PET/CT in predicting radiosensitivity of human nasopharyngeal carcinoma xenografts
Abstract
Objective
The purpose of the preliminary study was to investigate the value of 18F-FLT micro-PET/CT in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts in nude mice models.
Methods
Twelve BALB/c-nu nude mice were randomly divided into two groups. They were subcutaneously injected with either CNE1 or CNE2 cell suspension. Xenograft volumes were measured after tumor formation. When the tumors reached nearly 10 mm in diameter, they received 15-Gy irradiation. Before and 24 h after irradiation, mice were performed with 18F-FLT micro-PET/CT. The region of interest (ROI) was manually drawn, and the percent of injected dose per gram of the tumor and muscle in the ROIs was recorded. Tumor-to-muscle ratio (T/M) was calculated and compared with volume changes. Additionally, we also used ten untreated mice as control group.
Results
After irradiation, CNE2 tumors decreased significantly while CNE1 tumors continuously grew and became stable after 1 week. However, in control group, CNE1 and CNE2 tumors continuously enlarged in the observed time. Therefore, we could regard CNE2 group as irradiation responder while CNE1 group as non-responder. In irradiation group, the value of T/M before irradiation (T/M 0) of CNE1 mice was statistically lower than CNE2 mice (1.62 ± 0.38 versus 5.57 ± 1.30; P = 0.004). Besides, T/M decreased significantly in CNE2 group after irradiation (5.57 ± 1.30 versus 3.59 ± 1.06; P < 0.001). By means of a receiver operating characteristic curve, the optimal cut value of T/M 0 and ∆T/M to predict responder was 2.38 and −0.15, respectively (both sensitivity and specificity = 100.0 %).
Conclusions
18F-FLT PET/CT has the potential to predict radiosensitivity in NPC xenografts nude mice models.
Comparison of brain perfusion SPECT parameters accuracy for seizure localization in extratemporal lobe epilepsy with discordant pre-surgical data
Abstract
Objective
Extratemporal lobe epilepsy is difficult to localize. We aimed to define the best parameter(s) of SPECT for confirmation of seizure origin among the region of maximum cerebral perfusion in ictal phase (MP), maximum change of cerebral perfusion from interictal to ictal phase (MC), and maximum extent of hyperperfusion in ictal phase (ME) of 99mTc ECD brain perfusion SPECT as well as combined SPECT parameters, and combined SPECT and MRI for seizure localization in extratemporal lobe epilepsy.
Materials and methods
Twenty intractable extratemporal lobe epilepsy patients who had 99mTc-ECD brain SPECT were reviewed. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of single SPECT parameter, combined SPECT parameters, and combined SPECT and MRI parameters for localization of seizure origin were calculated using pathology and surgical outcomes (Engel class I and II) as gold standards.
Results
Combined SPECT parameters provided more specificity, PPV and accuracy than single SPECT parameters. The best combined SPECT parameters was MP+MC with 80.6 % accuracy, 92.4 % specificity and 43.8 % PPV. Combination of SPECT parameter with MRI (ME+MRI) was the most sensitive (41.7 %), specific (97.5 %), accurate (88.2 %) parameter and had highest PPV (76.9 %) and NPV (89.3 %) for seizure localization. It improved specificity and PPV when compared to MRI alone.
Conclusion
Combined SPECT parameters improved the specificity and accuracy in seizure localization. The most specific and accurate SPECT combination is MP+MC. The combined SPECT parameter with MRI further improved sensitivity, specificity, accuracy, PPV and NPV. The authors recommend using SPECT combination, MP+MC, when MRI is negative and ME+MRI when there is MRI lesion.
Improved spillover correction model to quantify myocardial blood flow by 11C-acetate PET: comparison with 15O-H2O PET
Abstract
Objective
11C-acetate has been applied for evaluation of myocardial oxidative metabolism and can simultaneously estimate myocardial blood flow (MBF). We developed a new method using two-parameter spillover correction to estimate regional MBF (rMBF) with 11C-acetate PET in reference to MBF derived from 15O-H2O PET. The usefulness of our new approach was evaluated compared to the conventional method using one-parameter spillover correction.
Methods
Sixty-three subjects were examined with 11C-acetate and 15O-H2O dynamic PET at rest. Inflow rate of 11C-acetate (K1) was compared with MBF derived from 15O-H2O PET. For the derivation, the relationship between K1 and MBF from 15O-H2O was linked by the Renkin-Crone model in 20 subjects as a pilot group. One-parameter and two-parameter corrections were applied to suppress the spillover between left ventricular (LV) wall and LV cavity. Validation was set using the other 43 subjects’ data. Finally, rMBFs were calculated using relational expression derived from the pilot-group data.
Results
The relationship between K1 and MBF derived from 15O-H2O PET was approximated as K1 = [1–0.764 × exp(−1.001/MBF)] MBF from the pilot data using the two-parameter method. In the validation set, the correlation coefficient between rMBF from 11C-acetate and 15O-H2O demonstrated a significantly higher relationship with the two-parameter spillover correction method than the one-parameter spillover correction method (r = 0.730, 0.592, respectively,p < 0.05).
Conclusion
In 11C-acetate PET study, the new two-parameter spillover correction method dedicated more accurate and robust myocardial blood flow than the conventional one-parameter method.
Lesion-based analysis of 18F-FDG uptake and 111In-Pentetreotide uptake by neuroendocrine tumors
Abstract
Purpose
To characterize the heterogeneity of metastatic neuroendocrine tumor (NET) lesions, we compared the [18F]-fluorodeoxyglucose (FDG) uptake and the 111In-pentetreotide (SRS) uptake for somatostatin receptor scintigraphy using the CT-based fusion imaging techniques of PET/CT and SPECT/CT.
Methods
Fifteen consecutive patients with NET lesions were examined using both FDG-PET/CT and SRS SPECT/CT prospectively. A total of 45 metastatic NET lesions were evaluated for FDG uptake according to the standardized uptake value (SUV) and for SRS uptake according to the tumor-to-muscle count ratio (T/M ratio); these values were then compared according to the grade of NET (G), also compared to the tumor volume.
Results
Both the SRS uptake and FDG uptake showed no significant correlation to the tumor volume, and suggested no significant artifacts in these data. The T/M ratio for the SRS uptake ranged from 192.7 to 1.9 and exhibited very wide range of distribution. The SUV for the FDG uptake ranged from 13.8 to 0.77 and exhibited narrow range of distribution. The uptake of the two tracers in individual lesions showed an inverse correlation. The G1 + 2 lesions had a higher SRS uptake than the G3 lesions, but the difference was not significant because of the large variation (40.65 ± 48.03, n = 39 vs. 8.66 ± 13.13, n = 6). However, the G1 + 2 lesions had a significantly lower FDG uptake than the G3 lesions (3.52 ± 1.84, n = 39 vs. 10.82 ± 4.50, n = 6). The tracer uptakes varied largely not only in an inter-subject manner, but also in an intra-subject manner.
Conclusion
An inverse correlation between SRS uptake and FDG uptake in the metastatic NET lesions observed in this study may be consistent with the opposing ideas of differentiation and proliferation in oncology. The large variations in SRS and FDG uptake by metastatic NET lesions suggest the biological heterogeneity of advanced NET. These results support the idea that combination therapy targeting both receptor-positive cells and proliferating cells may be beneficial from a functional imaging perspective.
Predictive value of SUV-based parameters derived from pre-treatment 18F-FLT PET/CT for short-term outcome with head and neck cancers
Abstract
Objective
The aim of this study was to investigate the predictive potential of pre-treatment 3′-deoxy-3′-[18F]-fluorothymidine (FLT) uptake parameters for short-term outcome of primary head and neck squamous cell cancer (HNSCC) patients.
Patients and methods
A total of 32 patients undergoing pre-treatment FLT positron emission tomography/computed tomography (PET/CT) from May 2010 to May 2013 were evaluated. Semi-quantitative assessment was used to determine mean, peak and maximum standardized uptake values (SUVmean, SUVpeak and SUVmax), metabolic tumor volume (MTV) and total lesion proliferation (TLP). Clinicopathologic factors and PET/CT parameters were analyzed for their association with 2-year loco-regional control (LRC) and overall survival (OS).
Results
The mean (± SD) SUVmean, SUVpeak, SUVmax, MTV and TLP were 5.97 ± 3.16, 6.71 ± 3.75, 10.05 ± 5.37, 7.31 ± 8.05 and 44.95 ± 52.82, respectively. In univariate analyses, N category was associated with OS (P = 0.037). Increased MTV ≥13 ml was associated with decreased LRC and OS (P < 0.0001). TLP ≥69.3 g was also linked with both LRC and OS (P = 0.009 and 0.015, respectively). Regarding SUVs, only the SUVpeak was associated with LRC and OS (P = 0.035 and 0.049, respectively).
Conclusions
Pre-treatment MTV is the most useful parameter with FLT PET/CT. TLP and SUVpeak may also provide important prognostic information for patients with HNSCCs.
Prosthesis infection: diagnosis after total joint arthroplasty with three-phase bone scintigraphy
Abstract
Objective
This study investigated the diagnostic validity of Three-phase bone scintigraphy (TPBS) for diagnosing prosthetic joint infection (PJI) in cases of suspected infected total joint arthroplasty.
Methods
We performed a systematic search using MEDLINE, EMBASE, and OVID databases to conduct pertinent data published between January 1990 and December 2013. Meta-analysis was used to pool sensitivity, specificity, diagnostic odds ratios (DORs), positive likelihood ratios (PLR), negative likelihood ratios (NLR), the area under the receiver-operating characteristic curve (AUC), and post-test probability. Heterogeneity and publication bias were assessed, and subgroup and meta-regression analyses were conducted.
Results
Twenty articles including a total of 704 patients were considered for analysis. The pooled sensitivity and specificity for using TPBS to detect PJI was 0.83 [95 % confidence interval (CI) 0.72–0.90] and 0.73 (95 % CI 0.65–0.80), respectively. The AUC, PLR, NLR, and DOR were 0.85 (95 % CI 0.81–0.87), 3.1 (95 % CI 2.4–4.1), 0.23 (95 % CI 0.14–0.38), and 14 (95 % CI 7–26), respectively. Low clinical scenario-negative post-test probabilities were 7 %, and high clinical scenario-positive post-test probabilities were 90 %. Subgroup analyses indicated that the sensitivity and specificity of TPBS for detecting infected arthroplasty of the hip (0.81 and 0.78, respectively) were significantly higher than those of the knee (0.75 and 0.55, respectively; p < 0.05). There was no significant evidence of publication bias (p = 0.34).
Conclusions
TPBS has reasonable diagnostic value for detecting PJI and could be performed as a screening test or part of preoperative tests and analysed in conjunction with other findings at the time of suspected PJI, especially in those infections affecting the hip.
68Gallium- and 90Yttrium-/177Lutetium: “theranostic twins” for diagnosis and treatment of NETs
Abstract
Abundant expression of somatostatin receptors (SSTR) is frequently identified in differentiated neuroendocrine tumors and may serve as potential target for diagnostic imaging and treatment. This article discusses the “theranostic approach” of SSTR-targeting compounds including an overview of its role for diagnosis, staging and restaging, discussing its way to being established in clinical routine, and giving an outlook about further potentially relevant developments.
Using 18F-FLT PET to distinguish between malignant and benign breast lesions with suspicious findings in mammography and breast ultrasound
Abstract
Purpose
To investigate the diagnostic performance of 3′-deoxy-3′-[18F]fluorothymidine (18F-FLT) PET in women with suspicious breast findings on conventional imaging (mammography and breast ultrasound).
Methods
Twenty-eight women with suspicious findings on conventional imaging were enrolled. A whole-body PET/CT in the supine position (first PET) was performed 60 min after intravenous injection of 0.07 mCi/kg 18F-FLT, followed by a regional PET of the breast in the prone position (second PET). For each lesion, the SUVmax of the first PET (SUV1) and second PET (SUV2) were measured. For the receiver operating characteristic (ROC) analysis of the diagnostic parameters, of the cutoff points with sensitivities >90 %, we chose the one with highest specificity as the optimal cutoff point to obtain the corresponding sensitivity and specificity.
Results
A total of 34 breast lesions (21 benign, 13 malignant) were analyzed. The SUV1 and SUV2 of the malignant lesions (median values 4.6 vs. 4.4, respectively) were higher than those of the benign lesions that had medians of 1.2 and 1.0, respectively (P = 0.0001). The area under the ROC curve (AUC) of SUV1 (0.905) showed no significant difference from that of SUV2 (0.912) (P = 0.77). The sensitivity and specificity using SUV1 = 1.24 as cutoff were 92.3 and 52.4 %, and those using SUV2 = 1.5 as cutoff were 92.3 and 66.7 %, respectively.
Conclusion
18F-FLT PET showed acceptable diagnostic performance for suspicious breast findings on conventional imaging, and SUV2 showed higher specificity than SUV1.
Dual-phase 99mTc-MIBI scintigraphy with delayed neck and thorax SPECT/CT and bone scintigraphy in patients with primary hyperparathyroidism: correlation with clinical or pathological variables
Abstract
Purpose
The purpose of this study was to assess the relationship between 99mTc-MIBI and 99mTc-MDP bone scintigraphy and clinical or pathological variables, including preoperative serum PTH levels and tumor diameter, in patients with newly diagnosed PHPT.
Methods
Dual-phase 99mTc-MIBI planar scintigraphy was performed in 244 patients with PHPT. Of these patients, 155 underwent 99mTc-MDP bone scintigraphy to detect bone changes before parathyroidectomy. Factors influencing99mTc-MIBI scintigraphy and 99mTc-MDP bone scintigraphy detection rate were assessed using univariate and multivariate logistic regression analysis; optimal cutoff values for predicting positive 99mTc-MIBI and 99mTc-MDP bone scintigraphy were evaluated using ROC analysis.
Results
Among 244 patients, 174 (71.31 %) patients with 181 foci had a positive 99mTc-MIBI planar scintigraphy; delayed neck and thorax SPECT/CT could identify and locate the 99mTc-MIBI lesions but could not find more lesions than planar scintigraphy. 70 (28.69 %) patients had a negative 99mTc-MIBI planar scintigraphy. Tumor diameter, serum PTH level and symptoms were statistically significant predictive factors in predicting positive 9mTc-MIBI scintigraphy both univariate and multivariate logistic regression analyses. The optimal thresholds for tumor diameter and serum PTH by ROC analysis were 1.03 cm and 127.60 ng/L, respectively. Among 155 patients with bone scintigraphy, 99mTc-MDP bone scintigraphy showed positive finding in 80 (51.61 %) patients and negative finding in 75 patients. Univariate logistic regression analysis showed that patient age, sex, tumor diameter and PTH level (≥150 ng/L) were statistically significant in predicting positive 99mTc-MDP bone scintigraphy. Multivariate logistic regression analysis showed both tumor diameter and PTH ≥ 150 ng/L were statistically significant in predicting positive 99mTc-MDP bone scintigraphy. The optimal thresholds for tumor diameter and serum PTH by ROC analysis were 1.96 cm and 163.85 ng/L, respectively.
Conclusions
The utility of delayed neck and thorax SPECT/CT over dual-phase 99mTc-MIBI planar scintigraphy is that it can identify and locate a parathyroid tumor in about more than 70 % of patients in PHPT and provide the assistance for surgical planning. These studies also suggest that 99mTc-MIBI scintigraphy and 99mTc-MDP bone scintigraphy are closely correlated with tumor diameter and PTH; which may show negative results when tumor diameter is small and serum PTH level is low.