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F. Bashirzadeh



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    O28 - Endoscopy (ID 124)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Pulmonology + Endoscopy/Pulmonary
    • Presentations: 1
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      O28.02 - Grey Scale Texture Analysis of Endobronchial Ultrasound Mini Probe Guide Sheath Images for Prediction of Benign or Malignant Aetiology. (ID 1059)

      10:40 - 10:50  |  Author(s): F. Bashirzadeh

      • Abstract
      • Presentation
      • Slides

      Background
      Expert analysis of endobronchial ultrasound (EBUS) images obtained with the mini probe (MP) has established certain subjective criteria for predicting benign or malignant disease. Minimal data is available for objective analysis of these images. The aim of this study was to determine if greyscale texture analysis of EBUS-MP images could differentiate between benign and malignant peripheral lung lesions.

      Methods
      Digital EBUS-MP images with contrast set at 4 and gain set at 10 were included in this study. A region of interest (ROI) was mapped for each image and analysed in a prediction set. The ROIs were analysed for the following greyscale texture features in MATLAB (v7.8.0.347 (R2009a)); mean pixel value, difference between maximum and minimum pixel value, standard deviation of the mean pixel value, entropy, correlation, energy and homogeneity. Significant greyscale texture features were used to assess a validation set. Figure 1

      Results
      Eighty-five peripheral lung lesions were in the prediction set (47 malignant and 38 benign). Benign lesions had larger differences between maximum and minimum pixel values, larger standard deviations of the mean pixel values and a higher entropy than malignant lesions (p<0.0001 for all values). Eighty two peripheral lesions were in the validation set; 63/82 (76.8%) were correctly classified. Of these 45/49(91.8%) malignant lesions and 18/33 (54.5%) benign lesions were correctly classified. The negative predictive value for malignancy was 82% and the positive predictive value was 75%. Figure 1

      Conclusion
      Greyscale texture analysis of EBUS-MP images could assist in differentiating between benign and malignant peripheral lung lesions but tissue diagnosis is still important.

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    P3.17 - Poster Session 3 - Bronchoscopy, Endoscopy (ID 185)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track:
    • Presentations: 1
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      P3.17-004 - Breath-hold low dose CT immediately following PET/CT enables good quality Virtual Bronchoscopy prior to EBUS guide sheath biopsy (ID 2109)

      09:30 - 09:30  |  Author(s): F. Bashirzadeh

      • Abstract

      Background
      Virtual Bronchoscopy (VB) facilitates localization of small lesions at EBUS Guide sheath(GS). A good quality CT to create the VB can be problematic to obtain in a timely fashion. Most lung cancer patients require PET, hence we explored options of getting the VB CT at PET upon initial referral prior to EBUS GS.

      Methods
      We compared VB results for consecutive CTs acquired in one of 3 ways. These were: Group1 :reconstructed CT from the PET/CT ( tidal breathing), Group 2: a dedicated low dose inspiratory breath-hold CT as part of PET/CT, and Group 3 conventional diagnostic CT. CTs had volumetric acquisition and 1 mm overlapping cuts were derived giving at least 600 DICOM images per scan. DICOM images were loaded onto a Lung Point® VB device and VB created. This device gives automated results for the number of bronchial divisions visible, and nearest distance to lesion in question after creation of the VB. Data for Dose Length Product (DLP) and CT Dose Index (CTDI) were obtained for each scan. DLP for Group 1 included whole body CT whereas DLP for Group 2 is stated just for the Thorax CT.

      Results

      Group 1 Tidal breathing Group2 Breath hold Group3 Conventional CT
      n 18 17 20
      Lesion size (mm) 21.1± 12.0 23.8±11.0 21.6±7.2
      Bronchial divisions 3.25±0.9 4.49±1.1, p<0.01 4.55±0.5 p<0.01
      proximity to target lesion (mm) 25.8±19.5 6.7±6.3, p<0.001 cf Gp1 13.3±9.2, p<0.02 cf Gp1
      DLP 435 ± 31 173 ± 77 341 ±94, p<0.001 cf Gp 2
      CTDI 3.9 ± 1.3 4.1 ± 1.9 8.9±2.9, p<0.001 cf Gp2
      % lesions reached at EBUS GS 83 85 90
      % positive pathology at EBUS GS 58 54 63
      In Group 2 unexpected positive mediastinal nodes were seen on PET enabling staging and diagnostic EBUS TBNA confirming malignancy to be done instead of EBUS GS in 3 patients. Poor VB results with the reconstructed CT were due to underlying COPD with small airway closure and hence inability of the software to detect these small airways; (scans acquired in both inspiration and expiration).

      Conclusion
      Low dose single breath-hold CT at the time of PET gives at least equivalent results to dedicated CT with far less radiation exposure, and is technically superior to reconstructed CT. Higher visualised bronchial number allows closer proximity to lesions by the directed path. Obtaining this CT prior to EBUS GS means no additional high dose CT is required and additional nodal staging results with the PET can make for better procedural decision making.

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    P3.19 - Poster Session 3 - Imaging (ID 181)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      P3.19-004 - Comparison of objective criteria and expert visual interpretation to classify benign and malignant hilar and mediastinal nodes on 18-F FDG PET/CT. (ID 1398)

      09:30 - 09:30  |  Author(s): F. Bashirzadeh

      • Abstract

      Background
      Despite the widespread adoption of FDG-PET/CT in staging of lung cancer, there are no universally accepted criteria for classifying thoracic nodes as malignant. Previous studies have generally shown high negative predictive values, but there are varying reporting criteria and positive predictive values for classifying malignant involvement. Using Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) histology as the gold standard, we evaluated objective 18-F FDG-PET/CT criteria for interpreting mediastinal and hilar nodes and compared this to expert visual interpretation (EVI).

      Methods
      A retrospective review of all patients with proven/suspected primary lung cancer who had both FDG-PET/CT and EBUS-TBNA from 2008-2010 was performed. Scan interpretation was blinded to histology. Separate prediction and validation datasets were used. 104 patients from 2008/2009 formed the prediction set; 48 patients from 2010 formed the validation set. Objective FDG-PET/CT criteria were: - SUVmax lymph node (SUVmaxLN) - Ratio SUVmaxLN/SUVmax primary lung malignancy if evident (R-SUVmax primary) - Ratio SUVmaxLN/SUVaverage liver (R-SUVavg liver) - Ratio SUVmaxLN/SUVmax liver (R-SUVmax liver) - Ratio SUVmaxLN/SUVmax blood pool (R-SUVmaxBP) An experienced Nuclear Medicine Physician visually reviewed all scans and classified each thoracic nodal station as benign, malignant, or equivocal. For statistical analysis, ‘equivocal’ nodes were classified benign.

      Results
      87 malignant lymph nodes from 75 patients and 41 benign nodes from 21 patients were in the prediction set. All objective 18-F FDG-PET/CT criteria analysed were significantly higher in the malignant group compared to the benign group (p<0.0001 all criteria). EVI had 95.3% accuracy, with 83/87(95.4%) malignant nodes and 39/41(95.1%) benign nodes correctly classified. 34 malignant nodes from 34 patients and 19 benign nodes from 14 patients were in the validation set. The new proposed cut-off values of the objective criteria from the prediction set correctly classified 44/53(83.0%) nodes, with 28/34(82.4%) malignant nodes and 16/19(84.2%) benign nodes correctly classified. EVI had 91% accuracy, with 33/34(97.1%) malignant nodes and 15/19 (79.0%) benign nodes correctly classified. Figure 1

      Conclusion
      Objective analysis of 18-F FDG PET/CT can differentiate between malignant and benign nodes with high accuracy, but is not superior to EVI. For objective criteria to perform optimally, there may need to be different criteria devised for different patient populations.