A position-adaptive noise-reduction method using a deep denoising filter bank for dedicated breast positron emission tomography images.

Dedicated breast positron emission tomography (db-PET) is more sensitive than whole-body positron emission tomography and is thus expected to detect early stage breast cancer and determine treatment efficacy. However, it is challenging to decrease the sensitivity of the chest wall side at the edge of the detector, resulting in a relative increase in noise and a decrease in detectability. Longer acquisition times and injection of larger amounts of tracer improve image quality but increase the burden on the patient. Therefore, this study aimed to improve image quality via reconstruction with shorter acquisition time data using deep learning, which has recently been widely used as a noise reduction technique. In our proposed method, a multi-adaptive denoising filter bank structure was introduced by training the training data separately for each detector area because the noise characteristics of db-PET images vary at different locations. Input and ideal images were reconstructed based on 1- and 7-min collection data, respectively, using list mode data. The deep learning model used residual learning with an encoder-decoder structure. The image quality of the proposed method was superior to that of existing noise reduction filters such as Gaussian filters and nonlocal mean filters. Furthermore, there was no significant difference between the maximum standardized uptake values before and after filtering using the proposed method. Taken together, the proposed method is useful as a noise reduction filter for db-PET images, as it can reduce the patient burden, scan time, and radiotracer amount in db-PET examinations.

Association Between 18F-Fluorodeoxyglucose Uptake and Mutation Status of Epidermal Growth Factor Receptor in Sinonasal Tract Cancer.

BACKGROUND/AIM: The Warburg effect of cancer has been applied to detect various carcinomas though the 18F-fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography with computed tomography (PET/CT). 18F-FDG-PET/CT in lung cancer predicted the mutation status of epidermoid growth factor receptor (EGFR). This study aimed to investigate whether 18F-FDG uptake parameters were significantly related to EGFR mutation status in patients with sinonasal tract squamous cell carcinoma (STSCC). PATIENTS AND METHODS: Twenty-nine tumor specimens of primary STSCC from patients with definitive treatment were collected. RESULTS: The 18F-FDG uptake from primary tumors was not different between mutant- and wild-status of EGFR on either Mann-Whitney U-test or the receiver operating curve. A metabolic tumor volume of ≥25 with the minimum p-value from the log-rank test for STSCC-specific survival was associated with a significantly shorter STSCC-specific, disease-free, local recurrence-free survival on the univariate and multivariate analyses adjusted for the clinical stage, treatment, and EGFR status. CONCLUSION: 18F-FDG-PET/CT did not predict mutation of the EGFR status in STSCC.

Detection Ability of 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Clinical T Classification of Synchronous Esophageal Cancer in Pharyngeal Cancer.

BACKGROUND/AIM: The utility of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) for clinical T classification of synchronous esophageal cancer (SEC) in pharyngeal cancer has not been fully elucidated. We investigated the association between 18F-FDG-PET/CT and clinical T classification for SEC. PATIENTS AND METHODS: We retrospectively enrolled 90 patients with pharyngeal cancer having both Lugol chromoendoscopy and 18F-FDG-PET/CT at pretreatment. The association between 18F-FDG-PET/CT and pathological examination was compared by the Fisher's exact test. RESULTS: Pathologically, 12 patients with SEC were diagnosed. The number of locations for SEC with cT1a, cT1b, and cT3 was 20, 1, and 1, respectively. Sensitivity for cT1a-cT3, cT1b-cT3, and cT3 was 9.1%, 100%, and 100%, respectively. Locations of SEC with cT1b-cT3 were significantly detected. The locations of SEC with cT1b-cT3 were more frequently detected than those without cT1b-cT3 by 18F-FDG-PET/CT (p<0.01). CONCLUSION: Detection of SEC with clinical T1b-T3 in comparison to clinical T1a on pretreatment 18F-FDG-PET/CT for patients with pharyngeal cancer, was achieved with high sensitivity.

Metabolic Tumour Volume as a Predictor of Survival for Sinonasal Tract Squamous Cell Carcinoma.

BACKGROUND: High uptake of F18-fluorodeoxyglucose parameters for glucose metabolism is related to shorter survival in sinonasal tract cancer with various histological classifications. We investigated whether F18-fluorodeoxyglucose uptake parameters are associated with survival outcomes for patients with only squamous cell carcinoma (SCC) in the sinonasal tract that are treated either with surgery or nonsurgery. METHODS: We retrospectively observed F18-fluorodeoxyglucose uptake parameters on positron emission tomography with computed tomography for the primary tumour of SCC in 39 patients. Log-rank test or a Cox regression model with 95% confidence interval (95%CI) and hazard ratio (HR) were used for monovariable or multivariable analysis, respectively. We determined cut-off values of the F18-fluorodeoxyglucose uptake parameters using the lowest p value for monovariable sinonasal tract cancer-specific survival analysis. RESULTS: Monovariable analysis showed that patients with metabolic tumour volume (MTV) ≥ 21.8 had a shorter cancer-specific, disease-free and local recurrence-free survival than those with MTV < 21.8. After adjusting for age, gender, clinical stage and treatment group in the multivariable analysis, MTV (≥21.8/<21.8) was related to shorter cancer-specific (HR: 3.69, 95%CI: 1.17-12.0), disease-free (HR: 3.38, 95%CI: 1.19-9.71) and local recurrence-free (HR: 5.42, 95%CI: 1.59-20.3) survivals. CONCLUSIONS: MTV as advances in diagnostics of sinonasal tract SCC is a predictor.

Total lesion glycolysis as a predictor of clinical T3-4a laryngeal cancer with laryngectomy or nonlaryngectomy.

ABSTRACT: The purpose of the present study is to investigate whether the 18F-fluorodeoxyglucose (18F-FDG) uptake parameter is related to survival outcomes for patients with clinical T3-T4a laryngeal cancer with various definitive treatments including total laryngectomy (TL). Parameters of 18F-FDG uptake in the primary tumors of 46 cases which were assessed by positron emission tomography with computed tomography were enrolled in the present observation study. Monovariate or multivariate survival analyses were performed with log-rank test or Cox regression model, with the hazard ratio (HR) and 95% confidence interval (CI), respectively. Cutoff values of the 18F-FDG uptake parameters were determined by the lowest P-value for monovariate overall survival. In the monovariate analysis, both metabolic tumor volume ≥13.1 and total lesion glycolysis (TLG) ≥46.5 were significantly associated with shorter overall survival, and TLG ≥46.5 was also related to a reduction in distant metastasis-free survival. In the multivariate analysis adjusting for clinical T classification (cT4/cT3) and treatment group (TL/non-TL), TLG (≥46.5/<46.5) was associated with both poorer overall (HR: 3.16, 95% CI: 1.10-9.49) and distant metastasis-free (HR: 8.91, 95% CI: 1.93-62.6) survival. In conclusion, TLG is a predictor for survival in laryngeal cancer.

Utility of CT texture analysis to differentiate olfactory neuroblastoma from sinonasal squamous cell carcinoma.

The purpose of this study was to examine differences in texture features between olfactory neuroblastoma (ONB) and sinonasal squamous cell carcinoma (SCC) on contrast-enhanced CT (CECT) images, and to evaluate the predictive accuracy of texture analysis compared to radiologists' interpretations. Forty-three patients with pathologically-diagnosed primary nasal and paranasal tumor (17 ONB and 26 SCC) were included. We extracted 42 texture features from tumor regions on CECT images obtained before treatment. In univariate analysis, each texture features were compared, with adjustment for multiple comparisons. In multivariate analysis, the elastic net was used to select useful texture features and to construct a texture-based prediction model with leave-one-out cross-validation. The prediction accuracy was compared with two radiologists' visual interpretations. In univariate analysis, significant differences were observed for 28 of 42 texture features between ONB and SCC, with areas under the receiver operating characteristic curve between 0.68 and 0.91 (median: 0.80). In multivariate analysis, the elastic net model selected 18 texture features that contributed to differentiation. It tended to show slightly higher predictive accuracy than radiologists' interpretations (86% and 74%, respectively; P = 0.096). In conclusion, several texture features contributed to differentiation of ONB from SCC, and the texture-based prediction model was considered useful.

Association between treatment package time and clinical predictors in oropharyngeal cancer.

The aim of the present study is to investigate the association of treatment package time with the survival outcomes and clinical parameters in patients with oropharyngeal squamous cell carcinoma.A total of 49 patients who underwent definitive treatment were enrolled. The treatment package time was calculated in days from the start of any treatment to the completion of all treatments, including postoperative treatment and salvage surgery for residual tumor.On univariate analyzes, treatment package time ≥118 days, sake index ≥60, Brinkman index ≥450, maximum standardized uptake value ≥42.45, and the presence of synchronous cancer were significantly associated with shorter oropharyngeal squamous cell carcinoma-specific survival. Moreover, a treatment package time of ≥118 days was significantly correlated with shorter overall survival and distant metastasis-free survival. On multivariate analyzes, Brinkman index ≥450 was significantly associated with shorter oropharyngeal squamous cell carcinoma-specific and locoregional recurrence-free survival, and the presence of synchronous cancer was significantly associated with shorter overall and distant metastasis-free survival.In conclusion, a relatively long treatment package time was a predictor of low survival outcomes in oropharyngeal squamous cell carcinoma by univariate analysis.

Clinical relevance of fluorodeoxyglucose positron emission tomography/computed tomography and magnifying endoscopy with narrow band imaging in decision-making regarding the treatment strategy for esophageal squamous cell carcinoma.

BACKGROUND: Recent advances in endoscopic technology, especially magnifying endoscopy with narrow band imaging (ME-NBI) enable us to detect superficial esophageal squamous cell carcinoma (ESCC), but determining the appropriate method of resection, endoscopic resection (ER) vs surgical resection, is often challenging. Recently, several studies have reported that 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a useful indicator for decision-making regarding treatment for superficial ESCC. Although, there are not enough reports on association between FDG-PET uptake and clinicopathological characteristics of superficial ESCC. And, there are not enough reports on evaluating the usefulness of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC. This study evaluated clinical relevance of FDG-PET and ME-NBI in decision-making regarding the treatment strategy for ESCC. AIM: To investigate the association between FDG uptake and the clinicopathological characteristics of superficial ESCC and its usefulness of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC. METHODS: A database of all patients with superficial ESCC who had undergone both ME-NBI and FDG-PET for pre-treatment staging at Aichi Cancer Center Hospital between January 2008 and November 2018 was retrospectively analyzed. FDG uptake was defined positive or negative whether the primary lesion was visualized or could be distinguished from the background, or not. The invasion depth of ESCC was classified according to the Japan Esophageal Society. Primary endpoint is to evaluate the association between FDG uptake and clinicopathological characteristics of superficial ESCC. Secondary endpoint is to investigate the efficacy of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC. RESULTS: A total of 82 lesions in 82 patients were included. FDG-PET showed positive uptake in 29 (35.4%) lesions. Univariate analysis showed that uptake of FDG-PET had significant correlations with circumferential extension (P = 0.014), pathological depth of tumor invasion (P < 0.001), infiltrative growth pattern (P < 0.001), histological grade (P = 0.002), vascular invasion (P = 0.001), and lymphatic invasion (P < 0.001). On multivariate analysis, only depth of tumor invasion was independently correlated with FDG-PET/computed tomography visibility (P = 0.018). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of Type B2 in ME-NBI for the invasion depth of T1a muscularis mucosae and T1b upper submucosal layer were 68.4%/79.4%/50.0%/89.3%/76.8%, respectively, and those of Type B3 for the depth of T1b middle and deeper submucosal layers (SM2 and SM3) were 46.7%/100%/100%/89.3%/90.2%, respectively. On the other hand, those of FDG-PET for SM2 and SM3 were 93.3%/77.6%/48.2%/98.1%/80.5%, respectively, whereas, if the combination of positive FDG uptake and type B2 and B3 was defined as an indicator for radical esophagectomy or definitive chemoradiotherapy, the sensitivity, specificity, PPV, NPV, and accuracy were 78.3%/91.5%/78.3%/91.5%/87.8%, respectively. CONCLUSION: FDG uptake was correlated with the invasion depth of superficial ESCC. Combined use of FDG-PET and ME-NBI, especially with the microvascular findings of Type B2 and B3, is useful to determine whether ER is indicated for the lesion.

Uptake of 18F-Fluorodeoxyglucose in Major Salivary Gland Cancer Predicts Survival Adjusting for Pathological Stage.

AIM: To investigate whether 18F-fluorodeoxyglucose uptake is associated with overall survival in patients with major salivary gland cancer using univariate and multivariate analyses after adjusting for pathological stage (eighth edition of the International Union Against Cancer). PATIENTS AND METHODS: A total of 32 patients with major salivary gland cancer treated with curative surgery were enrolled. Parameters for 18F-fluorodeoxyglucose uptake were assessed by positron-emission tomography combined with computed tomography. RESULTS: Using univariate and multivariate analyses after adjusting for pathological stage, a maximum standardized uptake value ≥26, peak standardized uptake value ≥20.3, metabolic tumor volume ≥9.7, and total lesion glycolysis ≥263 were significantly correlated with shorter overall survival. CONCLUSION: Parameters of 18F-fluorodeoxyglucose uptake in major salivary gland cancer are predictive of overall survival after adjusting for the pathological stage.

Peak of Standardized Uptake Value in Oral Cancer Predicts Survival Adjusting for Pathological Stage.

BACKGROUND/AIM: To predict survival outcomes of different patients with the same stage of disease is difficult. The possible correlation between 18F-fluorodeoxyglucose (18F-FDG) uptake parameters and survival outcomes was investigated in oral squamous cell carcinoma patients by multivariate analysis adjusted for the pathological stage according to the 8th edition of the tumor-node-metastasis (TNM) classification of the Union for International Cancer Contro. PATIENTS AND METHODS: 18F-FDG-uptake parameters of 28 patients were assessed by positron emission tomography with computed tomography (PET/CT). RESULTS: A peak of standardized uptake value of primary tumor (p-SUVpeak) of ≥14.1 was significantly correlated with shorter overall survival by univariate and multivariate analyses adjusted for the pathological TNM stage. A p-SUVpeak of ≥14.1 was significantly associated with shorter local recurrence-free survival and disease-free survival. CONCLUSION: A higher p-SUVpeak on pretreatment 18F-FDG-PET/CT is a prognostic parameter of identifying lower survival outcomes.

Total lesion glycolysis on FDG-PET/CT before salvage surgery predicts survival in laryngeal or pharyngeal cancer.

We investigated whether 18F-fluorodeoxyglucose uptake parameters using positron emission tomography combined with computed tomography predicts several survival outcomes, including lung metastasis-free survival, in patients with laryngeal or pharyngeal cancer who underwent salvage surgery. The maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis were calculated as 18F-fluorodeoxyglucose uptake parameters in 51 patients with laryngeal or pharyngeal cancer before salvage surgery. In univariate analysis, the maximum standardized uptake value ≥ 22.8, metabolic tumor volume ≥ 2.4, and total lesion glycolysis ≥ 5.4 were significantly correlated with shorter overall survival. In multivariate analysis with adjustment for clinical stage, patients with total lesion glycolysis ≥ 5.4 exhibited significantly shorter overall survival. Furthermore, total lesion glycolysis ≥ 5.4 was significantly correlated with shorter disease-specific survival, distant metastasis-free survival, and lung metastasis-free survival in univariate analysis. In conclusion, total lesion glycolysis predicts the survival outcomes including lung metastasis in patients with laryngeal or pharyngeal cancer who underwent salvage surgery.

Evaluation of lobar lymph node metastasis in non-small cell lung carcinoma using modified total lesion glycolysis.

BACKGROUND: Volumetric parameters based on 3-dimensional reconstruction have recently been introduced for cancer staging. We aimed to improve the ability to diagnose hilar lymph node metastasis in patients with non-small cell lung cancer. METHODS: We evaluated 142 patients with non-small cell lung cancer who underwent right upper lobectomy and radical lymph node dissection. Metastatic involvement of right upper lobar lymph nodes was assessed using high-resolution computed tomography (HRCT) and 18F-2-floro-2-deoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT). RESULTS: On receiver operating characteristic (ROC) curve analysis, the area under the curves (AUC) for short axis, maximum of standardized uptake value (SUVmax), total lesion glycolysis (TLG) and modified TLG (mTLG) were 0.79, 0.77, 0.76, and 0.87, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of mTLG, using the optimal cut off value (2.45), for diagnosis of lobar lymph node metastasis were 71%, 88%, 44%, and 96%, respectively. Hilar asymmetric uptake (HAU) of FDG was larger in true-positive cases than in false-negative cases (P<0.01). Furthermore, the size of metastatic foci in the lymph node was smaller in false-negative cases (P=0.012). CONCLUSIONS: Modified TLG is a good parameter to diagnose metastatic right upper lobar lymph nodes. Micrometastasis in the lymph node is difficult to predict using the current diagnostic method. However, more careful evaluation is required in patients with symmetric FDG accumulation at hilar region because hilar lymph nodes respond to various causes such as benign pulmonary diseases.

FDG-PET/CT predicts survival and lung metastasis of hypopharyngeal cancer in a multi-institutional retrospective study.

OBJECTIVES: We investigated a possible correlation between the maximum standardized uptake value (SUVmax), which is assessed by pretreatment 18F-fluorodeoxyglucose positron emission tomography with computed tomography, and the overall survival (OS) in patients with hypopharyngeal squamous cell carcinoma from two institutions on long-term follow-up, and examined whether SUVmax is correlated with several survival outcomes, including lung metastasis-free survival. METHODS: A total of 81 patients were enrolled. The survival rate was calculated by the Kaplan-Meier method. Both univariate and multivariate survival analyses were assessed by a Cox proportional hazards model. RESULTS: SUVmax ≥15.2 in institution A (p = 0.0306) or SUVmax ≥8 in institution B (p = 0.0132) was significantly predictor of a lower OS. We disaggregated the data by high SUVmax (SUVmax ≥15.2 from institution A and SUVmax ≥8 from institution B) and low SUVmax (SUVmax <15.2 from institution A and SUVmax <8 from institution B). Patients with a high SUVmax exhibited a significantly lower OS in both univariate (p = 0.001) and multivariate (p = 0.0046) analyses for adjusted for the clinical stage and treatment group. The patients with a high SUVmax exhibited significantly shorter disease-specific (p = 0.0068), distant metastasis-free (p = 0.0428), and lung metastasis-free (p = 0.0328) survivals. CONCLUSIONS: High SUVmax was significantly correlated with a lower OS, disease-specific survival, distant metastasis-free survival, and lung metastasis-free survival in a multi-institutional retrospective study.

Impact of total lesion glycolysis measured by 18F-FDG-PET/CT on overall survival and distant metastasis in hypopharyngeal cancer.

The present study investigated the possible correlation between 18F-2-fluorodeoxyglucose (18F-FDG)-uptake parameters and clinicopathological parameters in hypopharyngeal squamous cell carcinoma (HPSCC). A total of 53 patients, newly diagnosed with HPSCC, received pretreatment 18F-FDG-positron emission tomography/computed tomography (PET/CT). Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum and peak standardized uptake values (SUVmax and SUVpeak) were calculated as 18F-FDG-uptake parameters of the primary tumor. Tumor thickness, depth of invasion and pathological tumor volume were pathologically measured. Upon univariate survival analysis, SUVmax ≥28.5, SUVpeak ≥19, MTV ≥12 and TLG ≥42 were significantly associated with a shorter overall survival (OS) time, and MTV ≥12 and TLG ≥42 were significantly associated with a shorter distant metastasis-free survival (DMFS) time. Upon multivariate analysis with adjustment for clinical T category and treatment group, patients with SUVmax ≥28.5 exhibited a significantly shorter OS time, while TLG ≥42 was significantly correlated with shorter OS and DMFS times. Upon simple regression analysis, TLG was found to be significantly associated with tumor thickness and depth of invasion, while MTV was found to be closely associated with pathological tumor volume. In conclusion, pretreatment 18F-FDG-PET/CT is likely to provide valuable prognostic parameters in HPSCC.

Automated detection of pulmonary nodules in PET/CT images: Ensemble false-positive reduction using a convolutional neural network technique.

PURPOSE: Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be further reduced. In this paper, the authors propose an improved FP-reduction method for the detection of pulmonary nodules in PET/CT images by means of convolutional neural networks (CNNs). METHODS: The overall scheme detects pulmonary nodules using both CT and PET images. In the CT images, a massive region is first detected using an active contour filter, which is a type of contrast enhancement filter that has a deformable kernel shape. Subsequently, high-uptake regions detected by the PET images are merged with the regions detected by the CT images. FP candidates are eliminated using an ensemble method; it consists of two feature extractions, one by shape/metabolic feature analysis and the other by a CNN, followed by a two-step classifier, one step being rule based and the other being based on support vector machines. RESULTS: The authors evaluated the detection performance using 104 PET/CT images collected by a cancer-screening program. The sensitivity in detecting candidates at an initial stage was 97.2%, with 72.8 FPs/case. After performing the proposed FP-reduction method, the sensitivity of detection was 90.1%, with 4.9 FPs/case; the proposed method eliminated approximately half the FPs existing in the previous study. CONCLUSIONS: An improved FP-reduction scheme using CNN technique has been developed for the detection of pulmonary nodules in PET/CT images. The authors' ensemble FP-reduction method eliminated 93% of the FPs; their proposed method using CNN technique eliminates approximately half the FPs existing in the previous study. These results indicate that their method may be useful in the computer-aided detection of pulmonary nodules using PET/CT images.

Correlation between 18F-FDG-uptake and in vitro chemosensitivity of cisplatin in head and neck cancer.

AIM: High [18F]-2-fluorodeoxyglucose (18F-FDG) -uptake of primary tumor, assessed by pretreatment positron emission tomography combined computed tomography (PET/CT), has indicated poor overall survival (OS) in head and neck cancer (HNC).We investigated the correlation between 18F-FDG-uptake and in vitro chemosensitivity of cisplatin using histoculture drug response assay in HNC. PATIENTS AND METHODS: Twenty-eight patients were evaluated. The maximum standardized uptake value (SUVmax) and inhibition index (I.I.) cisplatin were calculated as 18F-FDG-uptake and in vitro chemosensitivity of cisplatin. RESULTS: Each SUVmax10.5 or I.I.cisplatin<50 could significantly differentiate shorter survival group by OS analyses. I.I.cisplatin of patients with SUVmax≥10.5 was significantly greater. In 19 patients with SUVmax≥10.5, those who received treatment with cisplatin-based chemotherapy exhibited a significant correlation with longer OS. CONCLUSION: Cisplatin hasthe potential to improve OS for HNC patients that were predicted as shorter OS by 18F-FDG-PET/CT.

Evidence for bilateral endolymphatic hydrops in ipsilateral delayed endolymphatic hydrops: preliminary results from examination of five cases.

CONCLUSION: After the administration of a standard dose of gadodiamide, an intravenous gadolinium-based contrast agent (GBCA), magnetic resonance imaging (MRI) evaluation of endolymphatic hydrops (EH) became possible in patients with ipsilateral delayed endolymphatic hydrops (DEH). We found that patients with ipsilateral DEH may also have bilateral EH. OBJECTIVE: MRI evaluation contributes to understanding of the pathological conditions in patients with EH. However, double or triple the standard dose of GBCA is often required to obtain images of high quality. We attempted to examine EH bilaterally in patients with ipsilateral DEH after routine administration of an intravenous GBCA. METHODS: GBCA (gadodiamide, 0.2 ml/kg) was administered intravenously to five patients with ipsilateral DEH. Three-dimensional fluid attenuated inversion recovery (3D-FLAIR) MRI was performed with a 3-T MRI scanner 4 h after GBCA administration. RESULTS: In all five patients, EH was observed in the affected vestibules. Moreover, EH was observed bilaterally in four (80%) of five patients with ipsilateral DEH. The region of the deaf ear affected by EH was considerably larger compared with the normal ear in three patients. However, observed regions of EH were of approximately the same size in both ears in patients 4 and 5.

Hybrid method for the detection of pulmonary nodules using positron emission tomography/computed tomography: a preliminary study.

PURPOSE: In this study, an automated scheme for detecting pulmonary nodules using a novel hybrid PET/CT approach is proposed, which is designed to detect pulmonary nodules by combining data from both sets of images. METHODS: Solitary nodules were detected on CT by a cylindrical filter that we developed previously, and in the PET imaging, high-uptake regions were detected automatically using thresholding based on standardized uptake values along with false-positive reduction by means of the anatomical information obtained from the CT images. Initial candidate nodules were identified by combining the results. False positives among the initial candidates were eliminated by a rule-based classifier and three support vector machines on the basis of the characteristic features obtained from CT and PET images. RESULTS: We validated the proposed method using 100 cases of PET/CT images that were obtained during a cancer-screening program. The detection performance was assessed by free-response receiver operating characteristic (FROC) analysis. The sensitivity was 83.0% with the number of false positives/case at 5.0, and it was 8% higher than the sensitivity of independent detection systems using CT or PET images alone. CONCLUSION: Detection performance indicates that our method may be of practical use for the identification of pulmonary nodules in PET/CT images.

Utility of high-definition FDG-PET image reconstruction for lung cancer staging.

BACKGROUND: High-definition (HD) positron emission tomography (PET) image reconstruction is a new image reconstruction method based on the point spread function system, which improves the spatial resolution of the images. PURPOSE: To compare the utility of HD reconstruction of PET images for staging lung cancer with that of conventional 2D ordered subset expectation maximization + Fourier rebinning (2D) reconstruction. MATERIAL AND METHODS: Thirty-five lung cancer patients (24 men, 11 women; median age, 66 years) who underwent surgery after 18F-2-deoxy-fluoro-D-glucose (FDG)-PET-CT were studied. Their PET data were reconstructed with 2D and HD PET reconstruction algorithms. Two radiologists individually TNM staged both sets of images. They also evaluated the quality of the images and the diagnostic confidence that the images afforded them using 5-point scales. RESULTS: T, N, and M stages were correctly diagnosed on both the 2D and HD reconstructed images in 23 (66%), 25 (71%), and 30 (86%) of 35 cases, respectively. Overall TNM stage was correctly diagnosed on both types of reconstructed images in 23 cases (66%), underestimated in three (9%), and overestimated in nine (26%). No significant difference in T, N, or M stage or overall TNM stage was observed between the two reconstruction methods. However, the HD reconstructed images afforded a significantly higher level of diagnostic confidence during TNM staging than the 2D reconstructed images and were also of higher quality than the 2D reconstructed images. CONCLUSION: Although HD reconstruction of FDG-PET images did not improve the diagnostic accuracy of lung cancer staging compared with 2D reconstruction, the quality of the HD reconstructed images and the diagnostic confidence level they afforded the radiologists were higher than those of the conventional 2D reconstructed images.

Observer variation study of the assessment and diagnosis of incidental colonic FDG uptake.

PURPOSE: The aim of this study was to evaluate the interpretations of incidental colonic 18F-FDG uptake made by 10 experienced readers and to more clearly identify the pattern of suspicious colonic FDG uptake. The potential contributions of delayed FDG-PET scanning and of immune fecal occult blood testing (FOBT) in making a diagnosis were also analyzed. MATERIALS AND METHODS: Visual interpretations by 10 readers were made for 147 FDG uptake sites from 126 PET scans (cancer, 38 sites; adenoma, 43 sites; and no abnormality, 66 sites) with colonic FDG uptake. Assessments for the early FDG-PET images were (1) FDG uptake pattern, (2) FDG uptake degree, and (3) likelihood of malignancy. For the delayed images, the assessments were (1) change in the FDG uptake position, (2) change in FDG uptake degree, and (3) likelihood of malignancy. The results of FOBT were analyzed independently of the visual interpretations. RESULTS: Interobserver agreement (κ) was 0.501 for assessing FDG uptake patterns, while agreement on assessing changes in uptake degree and changes in uptake position between early and delayed imaging were low (κ = 0.213-0.229). Logistic regression analysis indicated that 'FDG uptake patterns' and 'FDG uptake degree' were significantly related to decide on the suspicion of malignancy (p < 0.001) and the final result (p < 0.001). "Small localized" and "large irregular localized" types had a high probability of a lesion regardless of either (1) FDG uptake degree or (2) variation in the uptake between the early and the delayed image. The delayed image decreased false-positive cases for some FDG uptake patterns, but it had little impact on distinguishing clearly between "cancer or adenoma" and "normal". The addition of FOBT had little impact on the diagnosis. CONCLUSION: There was highest agreement among readers with respect to the recognition of specified colonic FDG uptake patterns, and this pattern recognition had the most influence on the diagnosis. "Small localized" and "large irregular localized" types had a high probability of a lesion. The addition of delayed imaging and of FOBT results to the early imaging did not have much impact on the diagnosis.