Preliminary results: prospective clinical study to assess image-based iterative reconstruction for abdominal computed tomography acquired at 2 radiation dose levels.

OBJECTIVE: The objective of this study was to compare image quality for abdominal computed tomographic (CT) images acquired at 200 and 50 mA s and reconstructed with image-based iterative reconstruction. MATERIALS AND METHODS: In this institutional review board-approved prospective study, 22 patients (mean [SD] age, 64.3 [14.4] years; male-female ratio, 12:10) gave informed consent for acquisition of additional abdominal CT images on 64-slice multi-detector CT (MDCT) (Siemens Definition Flash). Standard-dose images were acquired at 200 quality reference mA s, whereas low-dose images were acquired at 50 mA s (all series: 120 kV; 5-mm section thickness; pitch, 0.9:1). The low-dose images were reconstructed with a nonlinear 3-dimensional iterative image reconstruction (3D-IIR) (SafeCT; MedicVision, Tirat Carmel, Israel) (4 settings, namely, A1, A2, A3, and A4) and were assessed by 3 abdominal radiologists for lesion detection, image noise, and visibility of small structures. CATPHAN 500 was scanned at the respective doses to obtain noise spectral density and modulation transfer function. RESULTS: Subjective image noise was unacceptable at 50-mA s filtered back projection and improved to average in 50-mA s A1 and minimal or no noise in 50-mA s A4. However, the visibility of small structures was similar to standard-dose filtered back projection images on 50-mA s A2. Objective image noise was reduced to 66% for the 50-mA s 3D-IIR images (9.08 [2.3]/26.75 [6.8]). The modulation transfer function curve demonstrated resolution improvement in the low-dose images with the 3D-IIR technique, whereas the noise spectral density curve confirmed noise suppression in the 50-mA s 3D-IIR images. CONCLUSIONS: Three-dimensional iterative image reconstruction helps to lower image noise without affecting the visibility of small structures at "moderate" settings. Diagnostically acceptable abdominal CT examinations can be acquired at 75% lower-radiation dose with the help of the image-based iterative reconstruction technique.

Utility of Core Biopsy Specimen to Identify Histologic Subtype and Predict Outcome for Lung Adenocarcinoma.

BACKGROUND: Lung adenocarcinoma histologic subtype is an important indicator of patient outcomes, so preoperative knowledge of subtype may be helpful to guide surgical planning. We evaluated the sensitivity and prognostic efficacy of specimens from computed tomography-guided core needle biopsies to predict histologic subtype and patient outcome after surgery. METHODS: We retrospectively identified 221 patients with lung adenocarcinoma who underwent computed tomography-guided lung biopsy and subsequent surgical resection. Concordance, accuracy, specificity, and sensitivity of histologic subtypes from core biopsy specimens were compared with surgically resected specimens. Tumor characteristics and biopsy procedural factors were analyzed to determine impact on diagnostic sensitivity. Histologic subtype based on biopsy specimen, clinical, tumor, and treatment variables were also examined in relation to time to progression. RESULTS: Overall concordance of biopsy samples with the predominant subtype from surgical specimens was 77%. Specificity (sensitivity) of detecting a nonaggressive and aggressive subtype were 86% (93%) and 95% (48%), respectively. Length of core specimen and percentage subtype composition in the surgically resected specimen were correlated with improved sensitivity but to a lesser extent with aggressive subtypes. Presence of an aggressive subtype in biopsy specimens was an independent predictor of progression after surgery (subdistribution hazard ratio, 2.51; 95% confidence interval, 1.28-4.94; p = 0.0075). CONCLUSIONS: Specimens from computed tomography-guided core biopsies can predict lung adenocarcinoma progression after surgical resection. Future prospective studies should address the role of core biopsy in preoperative planning.