Image quality true non-enhanced and virtual non-enhanced images.

<p>TNE true non-enhanced CT, VNE_A VNE data acquired at the arterial phase, VNE_P VNE data acquired at the portal venous phase.</p><p>Image quality true non-enhanced and virtual non-enhanced images.</p

Excluded relevant anatomy.

<p>The yellow circle relates to the smaller (33 cm) field of view of the smaller detector. Iodine maps and subsequent iodine subtraction to create the virtual non-enhanced images can only be performed within the circle. In larger patients (>40 cm actual body diameter) or patients with improper position important anatomy may be excluded from the subtraction. In this example the lateral aspect of the right lobe of the liver fails to ‘become unenhanced’ (arrows).</p

Standard values applied for analysis of soft-tissue and fat-tissue attenuation.

<p>Standard values applied for analysis of soft-tissue and fat-tissue attenuation.</p

VNE images were acceptable for diagnosis purpose.

<p><b>a∼d</b> A 56-year-old man with advanced gastric cancer in the lesser curvature of the antrum. <b>a</b> Transverse CT scans show focal wall thickening (asterisk) of the lesser curvature of the gastric antrum with abnormal enhancement. VNE_A image (<b>c</b>), VNE_P image (<b>d</b>) and TNE image (<b>b</b>) show good correlation of measured CT numbers and thickness of the tumor (TNE: 39.7 HU±9.6, 1.84 cm; VNE_A: 37.3 HU±8.1, 1.58 cm; VNE_P: 38.3 HU±6.4, 1.90 cm). <b>e∼h</b> A 62-year-old man with advanced gastric cancer in the fundus. <b>e</b> Transverse CT scans show an enlarged lymph node (arrow) in the lesser curvature of the gastric body. VNE_A image (<b>g</b>), VNE_P image (<b>h</b>) and TNE image (<b>f</b>) show good correlation of measured CT numbers and diameter of the node (TNE: 37.6 HU±8.6, 1.66 cm; VNE_A: 40.0 HU±6.2, 1.77 cm; VNE_P: 34.1 HU±5.3, 1.71 cm). Both of the patients are noted excellent VNE image quality.</p

Proportion of measurements stratified per tissue type, with an absolute difference of >10 and >15 Hounsfield units between TNE and VNE images.

<p><b>a</b> Proportion of measurements stratified per tissue type, with an absolute difference of >10 and >15 Hounsfield units between TNE and VNE_A images. <b>b</b> Proportion of measurements stratified per tissue type, with an absolute difference of >10 and >15 Hounsfield units between TNE and VNE_P images.</p

Mean Length, CT value and noise of ROI measured in three series of non-enhanced images.

<p>TNE true non-enhanced CT, VNE_A VNE data acquired at the arterial phase, VNE_P VNE data acquired at the portal venous phase, LN lymph node, stomach normal stomach wall.</p><p>Mean Length, CT value and noise of ROI measured in three series of non-enhanced images.</p

Gastric Cancer Staging with Dual Energy Spectral CT Imaging

<div><p>Purpose</p><p>To evaluate the clinical utility of dual energy spectral CT (DEsCT) in staging and characterizing gastric cancers.</p><p>Materials and Methods</p><p>96 patients suspected of gastric cancers underwent dual-phasic scans (arterial phase (AP) and portal venous phase (PP)) with DEsCT mode. Three types of images were reconstructed for analysis: conventional polychromatic images, material-decomposition images, and monochromatic image sets with photon energies from 40 to 140 keV. The polychromatic and monochromatic images were compared in TNM staging. The iodine concentrations in the lesions and lymph nodes were measured on the iodine-based material-decomposition images. These values were further normalized against that in aorta and the normalized iodine concentration (nIC) values were statistically compared. Results were correlated with pathological findings.</p><p>Results</p><p>The overall accuracies for T, N and M staging were (81.2%, 80.0%, and 98.9%) and (73.9%, 75.0%, and 98.9%) determined with the monochromatic images and the conventional kVp images, respectively. The improvement of the accuracy in N-staging using the keV images was statistically significant (p<0.05). The nIC values between the differentiated and undifferentiated carcinoma and between metastatic and non-metastatic lymph nodes were significantly different both in AP (p = 0.02, respectively) and PP (p = 0.01, respectively). Among metastatic lymph nodes, nIC of the signet-ring cell carcinoma were significantly different from the adenocarcinoma (p = 0.02) and mucinous adenocarcinoma (p = 0.01) in PP.</p><p>Conclusion</p><p>The monochromatic images obtained with DEsCT may be used to improve the N-staging accuracy. Quantitative iodine concentration measurements may be helpful for differentiating between differentiated and undifferentiated gastric carcinoma, and between metastatic and non-metastatic lymph nodes.</p></div

Water-based material decomposition images for a 62-year-old man with signet ring cell carcinoma obtained with dual energy spectral scan mode.

<p>Water-based material decomposition images for a 62-year-old man with signet ring cell carcinoma obtained with dual energy spectral scan mode.</p

Accuracies, sensitivities and specificities for the distinction of N0 vs. N+ using kVp images (Group A) and optimal monochromatic images (Group B) with histological examination as the reference standard among patients with non metastatic disease.

<p>Accuracies, sensitivities and specificities for the distinction of N0 vs. N+ using kVp images (Group A) and optimal monochromatic images (Group B) with histological examination as the reference standard among patients with non metastatic disease.</p

Same patient as Figure 3.

<p>Monochromatic image in portal phase demonstrated striation enhancement of blurring and wide reticular strands surrounding the outer border (arrow heads) of the tumor staged as T3 which was proved by histology.</p