Effect of threshold on the correlation between airflow obstruction and low attenuation volume in smokers assessed by inspiratory and expiratory MDCT

BACKGROUND

The estimation of emphysematous changes is very sensitive to computed tomography (CT) threshold level. In clinical practice, the predetermined threshold is usually set at -950 Hounsfield units (HU) for the detection of low attenuation volume (LAV). However, threshold levels that are tightly connected to pulmonary function abnormalities have not been determined.

PURPOSE

To determine the threshold level for calculating an LAV that closely reflects airflow limitation in patients with chronic obstructive pulmonary disease (COPD).

MATERIAL AND METHODS

Seventy-six consecutive non-COPD smokers and COPD patients underwent paired inspiratory and expiratory multidetector CT (MDCT). LAV% was segmented every 10 HU between -1000 and -750 HU to examine the correlation between LAV% and indexes of obstructive impairment.

RESULTS

LAV% gradually increased as the threshold level increased on both inspiratory and expiratory images. LAV% on inspiratory images was higher than that on expiratory images at all threshold levels between -1000 and -750 HU. The threshold level that correlated with obstructive impairment differed between the two images: -930 HU on inspiratory and -870 or -880 HU on expiratory images.

CONCLUSION

LAV% dramatically changed according to the threshold level on both inspiratory and expiratory images, indicating that LAV% is dependent on the attenuation threshold level in patients with COPD. The threshold linking LAV% to airflow limitation was higher on expiratory than on inspiratory images.

Preoperative hepatic CT perfusion as an early predictor for the recurrence of esophageal squamous cell carcinoma: initial clinical results

Reports suggest that hepatic blood flow may have an association with cancer progression. The aim of the present study was to evaluate whether the hepatic blood flow measured by CT perfusion (CTP) may identify patients at high-risk for postoperative recurrence of esophageal squamous cell carcinoma (ESCC). Prior to surgery, hepatic CTP images were obtained using a 320-row area detector CT. The data were analyzed by a commercially available software based on the dual input maximum slope method, and arterial blood flow (AF, ml/min/100 ml tissue), portal blood flow (PF, ml/min/100 ml tissue) and perfusion index [PI (%) = AF/AF + PF × 100] were measured. These parameters were compared with the pathological stage and outcome of the ESCC patients. Forty-five patients with ESCC were eligible for this study. The median follow-up period was 17 months, and recurrences were observed in 9 patients (20%). The preoperative PI values of the 9 patients with recurrence were significantly higher than those of the 36 patients without recurrence (23.9 vs. 15.9, P=0.0022). Patients were categorized into the following two groups; high PI (>20) and low PI (<20). The recurrence-free survival of the low PI group was significantly better than that of the high PI group (P<0.0001). A multivariate analysis showed that a high PI was an independent risk factor for recurrence (odds ratio, 19.1; P=0.0369). Therefore, the preoperative PI of the liver may be a useful imaging biomarker for predicting the recurrence of patients with esophageal cancer.

Quantitative assessment of cross-sectional area of small pulmonary vessels in patients with COPD using inspiratory and expiratory MDCT

OBJECTIVES

Structural and functional changes in pulmonary vessels are prevalent at the initial stages of chronic obstructive pulmonary disease (COPD). These vascular alterations can be assessed using cross-sectional area (CSA) of small pulmonary vessels. However, neither in non-COPD smokers nor in COPD patients it has been defined whether the structural changes of pulmonary vessels detected by paired inspiratory and expiratory CT scans are associated with emphysematous changes. We quantified the CSA and low attenuation area (LAA) and evaluated the changes in these parameters in the inspiratory and expiratory phases.

MATERIALS AND METHODS

Fifty consecutive non-COPD smokers and COPD patients were subjected to multi detector-row CT and the percentage of vessels with a CSA less than 5 mm(2) as well as the percentage LAA for total lung area (%CSA<5, %LAA, respectively) were calculated.

RESULTS

The %CSA<5 correlated negatively with %LAA. The %CSA<5 was lower in COPD patients with emphysema as compared with non-COPD smokers and COPD patients with or without mild emphysema. In addition, the %CSA<5 was lower in the no/mild emphysema subgroup as compared with non-COPD smokers. The respiratory phase change of %CSA<5 in COPD patients was greater than that in non-COPD smokers.

CONCLUSION

The percentage of small pulmonary vessels decreased as emphysematous changes increase, and this decrease was observed even in patients with no/mild emphysema. Furthermore, respiratory phase changes in CSA were higher in COPD patients than in non-COPD smokers.

Utility of arterial phase of dynamic CT for detection of intestinal ischemia associated with strangulation ileus

AIM: To clarify the usefulness of arterial phase scans in contrast computed tomography (CT) imaging of strangulation ileus in order to make an early diagnosis.

METHODS: A comparative examination was carried out with respect to the CT value of the intestinal tract wall in each scanning phase, the CT value of the content in the intestinal tract, and the CT value of ascites fluid in the portal vein phase for a group in which ischemia was observed (Group I) and a group in which ischemia was not observed (Group N) based on the pathological findings or intra-surgical findings. Moreover, a comparative examination was carried out in Group I subjects for each scanning phase with respect to average differences in the CT values of the intestinal tract wall where ischemia was suspected and in the intestinal tract wall in non-ischemic areas.

RESULTS: There were 15 subjects in Group I and 30 subjects in Group N. The CT value of the intestinal tract wall was 41.8 ± 11.2 Hounsfield Unit (HU) in Group I and 69.6 ± 18.4 HU in Group N in the arterial phase, with the CT value of the ischemic bowel wall being significantly lower in Group I. In the portal vein phase, the CT value of the ischemic bowel wall was 60.6 ± 14.6 HU in Group I and 80.7 ± 17.7 HU in Group N, with the CT value of the ischemic bowel wall being significantly lower in Group I; however, no significant differences were observed in the equilibrium phase. The CT value of the solution in the intestine was 18.6 ± 9.5 HU in Group I and 10.4 ± 5.1 HU in Group N, being significantly higher in Group I. No significant differences were observed in the CT value of the accumulation of ascites fluid. The average difference in the CT values between the ischemic bowel wall and the non-ischemic bowel wall for each subject in Group I was 33.7 ± 20.1 HU in the arterial phase, being significantly larger compared to the other two phases.

CONCLUSION: This is a retrospective study using a small number of subjects; however, it suggests that there is a possibility that CT scanning in the arterial phase is useful for the early diagnosis of strangulation ileus.

Use of multi-detector row CT for postoperative follow-up of biliary atresia patients with sequelae

BACKGROUND/AIMS

To evaluate the usefulness of multi-detector row computed tomography (MDCT) in the postoperative long-term follow-up of biliary atresia (BA) patients for detection of esophagogastric varices due to portal hypertension and intrahepatic bile duct (IHBD) dilatations. Well-developed esophagogastric varices can cause unexpected life-threatening rupture and contribute to the progression of hepatopulmonary vascular diseases. Dilated IHBDs can trigger cholangitis.

METHODS

After corrective surgery, 29 BA patients (median age 14 years, range 6 months to 27 years) with suspected long-term sequelae underwent 16-slice MDCT. Esophagogastric varices and IHBD dilatations were evaluated using reconstructed images. Detection rates for esophagogastric varices were compared between MDCT and endoscopic findings. Differences in detection rates for IHBD dilatations between MDCT and ultrasonography (US) were also investigated.

RESULTS

Detection rates for esophageal varices did not differ significantly between MDCT and endoscopy, while three cases positive only on MDCT, including one with hepatopulmonary syndrome, showed conspicuous peri-esophageal varices deep in the esophageal wall. MDCT showed a significantly higher detection rate than endoscopy (p = 0.03) for gastric fundal varices. MDCT with the maximum intensity projection disclosed IHBD dilatations in 17 postoperative BA cases, 15 out of which had past history of cholangitis, while US detected them in 6 cases (p = 0.003). In addition, MDCT was more advantageous for detecting IHBD dilatations, particularly those located in the posterior lobe.

CONCLUSIONS

Among postoperative BA patients, compared to endoscopy, MDCT had comparable and superior detection rates for esophageal and gastric fundal varices, respectively. MDCT also precisely demonstrated the location and extent of IHBD dilatations. In long-term follow-up of BA patients, MDCT can help determine follow-up strategies.

The classification of anatomic variations in the perigastric vessels by dual-phase CT to reduce intraoperative bleeding during laparoscopic gastrectomy

BACKGROUND

Laparoscopy-assisted distal gastrectomy (LADG) is a less invasive alternative compared with an open procedure. However, it is difficult to obtain a full-view image and to estimate the three-dimensional (3D) relationships between organs during laparoscopic procedures. Determining the vascular anatomy by 3D CT imaging has been shown to play a critical role in reducing the risks associated with laparoscopic gastric cancer surgery. The purpose of this study was to evaluate the clinical anatomic variations and to estimate its positive contribution in obtaining less intraoperative bleeding.

METHODS

Scanning was performed using a 64-row MDCT scanner. Three-dimensional CT images in the arterial and portal phase were reconstructed and fused together using the volume-rendering technique. The intraoperative bleeding findings were compared between two periods.

RESULTS

The anatomic variations of the celiac trunk were divided into six types. There were 159 patients with Adachi's type I, type II=8, type III=1, type IV=1, type V=2, type VI=3, and other=1. The inflows of the left gastric coronary vein (LCV) were divided into three types. The LCV flowed into the portal vein (PV) in 79 patients, into the splenic vein (SpV) in 65, and into the junction of these two veins in 27. The splenic artery was divided into flat type and curved type, and 65 cases (37%) showed the flat type. Intraoperative bleeding was significantly less between 2007 and 2008, in which the operations were performed without first making a 3D anatomy study, than in 2009, in which 3D anatomy studies were made and analyzed before surgery in all patients.

CONCLUSIONS

Dual-phase 3D CT is a useful and essential modality to visualize the precise anatomy around the stomach. As a result, by comparing 3D CT images with our classifications, it is believed that any surgeons may reduce the degree of intraoperative blood loss.

Role of perfusion CT in assessing tumor blood flow and malignancy level of gastric cancer

BACKGROUND/AIMS

Intratumoral hemodynamics or tumor perfusion is useful in understanding the pathological background of the cancer. A parameter for a non-invasive, preoperative assessment of tumor perfusion has yet to be developed.

METHODS

The study included 50 patients who underwent surgery for gastric cancer. Perfusion computed tomography (P-CT) was performed using a 16-row multidetector CT, and tumor blood flow (ml/min/100 g tissue) values were measured. We compared blood flow with histopathological characteristics and evaluated its correlation with microvessel density and tumor stromal density and calculated the ratio of vessels and stromal tissue.

RESULTS

There was a significant decrease in blood flow in advanced tumor depth, peritoneal dissemination and undifferentiated subtypes. Cases with Lauren's diffuse type carcinoma were found to have decreased blood flow compared to the mixed or intestinal type. As for the stromal structure, despite the lack of correlation with microvessel density, blood flow significantly decreased with increased stromal density.

CONCLUSIONS

Decreased blood flow value acquired from P-CT may reflect a progressive state of gastric cancer. The pathological background for this relation involves the tumor stroma. Tumor perfusion decreased as the stage and malignant character of the tumor advanced, and therefore P-CT could be a better strategy to estimate the malignancy level of cancer.