Preliminary study of whole-brain CT perfusion imaging in patients with intracranial tumours adjacent to large blood vessels

Evaluation of Magnetic Resonance Imaging for Microsurgical Efficacy and Relapse of Rolandic Meningioma

In this study, magnetic resonance imaging (MRI) was used to evaluate the relapse features of patients with Rolandic meningioma after the microsurgery. 53 patients with Rolandic meningioma were selected as the research objects, and they were divided into the relapse group (n = 16) and nonrelapse group (n = 37) according to whether patients had a relapse during the follow-up period. Differences in quality of life, ¹H-MRS index, vascular density, and cell proliferation between the two groups were assessed as well as imaging differences between the two groups were analyzed using MRI. The results showed that the patients' quality-of-life scores in the two groups increased notably after the surgical treatment (P < 0.05). Compared with the nonrelapse group, the proportion of irregular boundary and uneven enhancement of focal tissue in the relapse group was signally increased (P < 0.05). Compared with the nonrelapse group, cell proliferation index, vascular density and imaging index, mean tumor diameter, mean transit time (MTT), time to peak (TTP), fractional anisotropy (FA), choline (Cho)/N-acetylaspartic acid (NAA), Cho/creatine (Cr), lactic acid (Lac)/Cr, and the maximum value of relative cerebral blood volume (rCBVmax) in the relapse group were obviously increased (P < 0.05). However, the apparent dispersion coefficient, NAA/Cr, and Lac/NAA values decreased greatly (P < 0.05). To sum up, the microsurgical treatment helped improve the quality of life of patients with Rolandic meningioma, and MR imaging could be used to determine the relapse of Rolandic meningioma after microsurgical treatment.

Effect of Radiofrequency Ablation with Interventional Therapy of Hepatic Artery on the Recurrence of Primary Liver Cancer and the Analysis of Influencing Factors

Background

The probability of liver cancer recurring in patients after surgery is a serious threat to liver cancer patients. Radiofrequency ablation is widely employed in liver cancer cases. We explored the therapeutic effects and influencing factors of radiofrequency ablation combined with hepatic artery intervention in patients with recurrence of primary liver cancer surgery.

Methods

90 patients with primary liver cancer postoperative recurrence admitted to our hospital from January 2014 to February 2017 were selected as the research objects. The patients were randomly divided into the control group (n = 45) and combined treatment group (n = 45). The combined treatment group received radiofrequency ablation combined with hepatic artery interventional therapy, and the control group received hepatic artery interventional therapy. The short-term efficacy, AFP levels before and after treatment, and long-term survival results of the two groups were compared. Single-factor and multifactor analyses of the clinical information of the combined treatment group were carried out to find out the factors affecting the therapeutic effect of radiofrequency ablation combined with hepatic artery intervention on patients with recurrence of primary liver cancer.

Results

The total effective rate of short-term curative effect of the combined treatment group was higher than the control group, and there was a statistically significant difference existing (P < 0.05). After treatment, two groups of patients' AFP levels were greatly lower than before treatment, the AFP levels of the combined treatment group were significantly lower than the control group, and there was a statistically significant difference (P < 0.05). The survival rates of patients in the combined treatment group at the sixth month, the first year, and the second year after treatment were significantly higher than those of the control group, and there was a statistically significant difference (P < 0.05). The univariate results showed that, in the combined treatment group, there were statistically significant differences between the effective group and the ineffective group in tumor diameter, intact capsule, liver cirrhosis, intrahepatic spread, and tumor adjacent to large blood vessels (P < 0.05). The outcomes of multivariate analysis indicated that tumor diameter ≥ 3 cm, incomplete capsule, intrahepatic spread, and tumor adjacent to large blood vessels were risk factors for ineffective recurrence of patients with primary liver cancer after radiofrequency ablation combined with hepatic artery intervention (P < 0.05). Discussion. Tumor diameter ≥ 3 cm, incomplete capsule, intrahepatic spread, and tumor adjacent to large blood vessels are risk factors for the ineffectiveness of radiofrequency ablation combined with hepatic artery interventional therapy for patients with recurrence of primary liver cancer. It is necessary to increase the range of radiofrequency treatment, increase the temperature of the radiofrequency needle, and strengthen postoperative follow-up interventions based on the specific conditions of the patient's tumor.

Utility of dual-energy CT for predicting the vascularity of meningiomas

PURPOSE

Dual-energy computed tomography (DECT) can provide iodine, electron density (ED), and effective atomic number Z (Z_eff) maps, facilitating the identification of tissue types. We investigated whether DECT parameters can predict the vascularity of meningiomas.

METHOD

We acquired DECT and perfusion CT (PCT) images in 24 patients with histologically diagnosed meningioma. Regions of interest (ROIs) were placed at the tumor in iodine, ED, and Z_eff maps derived from DECT and in a blood volume (BV) map derived from PCT. To normalize these parameters' values, we divided them by the values of contralateral normal-appearing white matter, i.e., the relative (r)ED, rZ_eff, and rBV. The vascular density of the tumor specimens was immunohistochemically analyzed by calculating the von Willebrand factor-positive vessel wall. We calculated Pearson's correlation coefficients to determine the correlation with PCT/DECT parameters and an immunohistopathological index.

RESULTS

Contrast rZ_eff (r = 0.7020, p = 0.0001) and iodine (r = 0.5814, p = 0.0029) both had positive correlations with rBV derived from PCT. The rED values were negatively correlated with the rBV values (r = -0.4735, p = 0.0194), and the vascular density results confirmed positive correlations with rBV (r = 0.6909, p = 0.0002) and contrast rZ_eff (r = 0.4982, p = 0.0132) and a negative correlation with rED (r = -0.4265, p = 0.0377). Regarding the radiation exposure, the mean estimated volume CT dose index (CTDI_vol) of DECT was 33.1 ± 1.72 mGy, much lower than that of PCT (103.3 ± 4.65 mGy).

CONCLUSIONS

DECT predicted vascular density with lower radiation exposure compared to PCT. DECT could potentially replace PCT for evaluating the vascularity of meningiomas.

Assessment of longitudinal beam property and contrast uniformity for 256- and 320-row area detector computed tomography scanners in the 160-mm nonhelical volume-acquisition mode

Background

Because the x‐ray property of patient longitudinal axis in area detector computed tomography (ADCT) depends on a heel effect, radiation dose and beam quality are not uniform along the long axis of the patient.

Objective

This study aimed to measure the longitudinal beam properties and contrast uniformity of ADCT scanners in the 160‐mm nonhelical volume‐acquisition (NVA) mode and provide useful datasets for the radiation dose reduction in ADCT examinations.

Materials and Methods

Two different types of ADCT scanners were used in this study. To assess the heel effect in 256‐ and 320‐row ADCT scanners, we measured dose profile, half‐value layer, and iodine contrast uniformity along longitudinal beam direction.

Results

The maximum effective energy difference within a 160‐mm x‐ray beam is approximately 4 keV. Maximum radiation dose on the anode side of the x‐ray tube showed approximately 40%–45% reduction compared with that on the isocenter position; the heel effect properties longitudinally differed throughout the x‐ray beam, and the decrease in the radiation dose in 256‐ and 320‐row ADCT scanners was observed on the patient table side and gantry side respectively. The CT numbers of iodinated solutions for 256‐row ADCT scanner were independent of the heel effect; nevertheless, the CT numbers of 320‐row ADCT scanner tended to increase on the patient table (cathode) side.

Conclusion

This study reveals that the radiation dose on the anode side of the x‐ray tube shows approximately 40%–45% reduction compared with that on the isocenter position, and the heel effect properties for 256‐ and 320‐row ADCT scanners longitudinally differ throughout the x‐ray beam. The x‐ray tube for individual ADCT scanners is mounted in an opposite direction along the long axis of the patient.

Spinal canal meningioma mimicking posterior fossa ischemia on CT perfusion: A CT perfusion pitfall

The recent approach to treat acute stroke is to extend treatment window in patients with salvageable peri-infarct ischemia which increases the application of the perfusion imaging, specifically computed tomography perfusion (CTP). In this paper, I am presenting a case of left middle cerebral artery infarction which was evaluated by CTP under “code stroke.” The patient had an incidental spinal canal meningioma which was out of field of view in CTP but mimicked right cerebellar ischemia on CTP. Although ischemia has been previously reported within the peripheral parenchymal edema surrounding a meningioma, in this patient there was no evidence of edema in the right cerebellum on magnetic resonance imaging. I believe the CTP findings are secondary to steal phenomena at right vertebral artery or compression upon the venous plexus. Recently, by using modern computed tomography scanners, it is common to cover the entire brain in CTP. The emergency radiologist should be aware of this pitfall that spinal canal pathologies which are out of field of view can mimic posterior fossa ischemia.

A semi-automated volumetric software for segmentation and perfusion parameter quantification of brain tumors using 320-row multidetector computed tomography: a validation study

PURPOSE

We developed a semi-automated volumetric software, NPerfusion, to segment brain tumors and quantify perfusion parameters on whole-brain CT perfusion (WBCTP) images. The purpose of this study was to assess the feasibility of the software and to validate its performance compared with manual segmentation.

METHODS

Twenty-nine patients with pathologically proven brain tumors who underwent preoperative WBCTP between August 2012 and February 2015 were included. Three perfusion parameters, arterial flow (AF), equivalent blood volume (EBV), and Patlak flow (PF, which is a measure of permeability of capillaries), of brain tumors were generated by a commercial software and then quantified volumetrically by NPerfusion, which also semi-automatically segmented tumor boundaries. The quantification was validated by comparison with that of manual segmentation in terms of the concordance correlation coefficient and Bland-Altman analysis.

RESULTS

With NPerfusion, we successfully performed segmentation and quantified whole volumetric perfusion parameters of all 29 brain tumors that showed consistent perfusion trends with previous studies. The validation of the perfusion parameter quantification exhibited almost perfect agreement with manual segmentation, with Lin concordance correlation coefficients (ρ _c) for AF, EBV, and PF of 0.9988, 0.9994, and 0.9976, respectively. On Bland-Altman analysis, most differences between this software and manual segmentation on the commercial software were within the limit of agreement.

CONCLUSIONS

NPerfusion successfully performs segmentation of brain tumors and calculates perfusion parameters of brain tumors. We validated this semi-automated segmentation software by comparing it with manual segmentation. NPerfusion can be used to calculate volumetric perfusion parameters of brain tumors from WBCTP.

Additive value of 320-section low-dose dynamic volume CT in relation to 3-T MRI for the preoperative evaluation of brain tumors

PURPOSE

To assess whether 320-section low-dose dynamic volume computed tomography (320-LDVCT) with adaptive iterative dose reduction (AIDR) adds value to 3-T MRI for the preoperative evaluation of brain tumors.

METHODS

The study population was comprised of 16 consecutive patients with brain tumors who, in addition to preoperative 3-T MRI, underwent 320-LDVCT with AIDR. Two radiologists independently evaluated the CT and MRI studies; one measured the relative cerebral blood volume (rCBV) in the tumor and contralateral brain on CT and MR perfusion maps. Interobserver agreement was assessed by κ statistics.

RESULTS

In 3 of 16 patients (19 %), 320-LDVCT added diagnostic value to 3-T MRI studies with respect to the visualization of feeders (κ = 0.77), and in 12 (75 %) it helped the delineation of venous structures (κ = 0.71) and the relationship between the tumor and adjacent vessels (κ = 0.85). The average standardized rCBV value was 12.2 ± 2.40 (range 0.7-36.6) on MR and 8.80 ± 2.77 (range 0.8-38.0) on CT perfusion studies; the correlation between these values was very strong (r = 0.92, p < 0.0001). According to the neurosurgeons, 320-LDVCT added helpful information for surgery in 4 patients (25 %).

CONCLUSION

The 320-LDVCT can add value to 3-T MRI for the tumor feeders and relationship between the tumor and adjacent vessels.

The role of 4D CT angiography for preoperative screening in patients with intracranial tumors

INTRODUCTION

Four-dimensional computed tomography angiography (4D CTA) is now becoming an often used diagnostic imaging modality for the assessment of patients with intracranial tumors. The purpose of this study was to demonstrate the utility of 4D CTA for preoperative screening in patients with intracranial tumors as well as to examine the correlation between perfusion data and grading of gliomas.

METHODS

We performed preoperative screening using 320-row detector CT scanner in 186 patients with intracranial tumors, and 115 patients were finally included in the study. Time-resolved subtracted maximum intensity projection images and volume-rendered images were reconstructed to evaluate vascular structures, tumor staining and incidental lesions. We also evaluated the perfusion functional map for gliomas to find correlations between their vascularity and tumor grading.

RESULTS

We evaluated gliomas in 70 patients, meningiomas in 29, and other tumors in 16. Patients with gliomas of a pathologically higher grade showed high cerebral blood volume (p < 0.05). Tumor staining was observed on MIP images for 12 meningiomas, 4 gliomas, and 3 other tumors. Fifty patients showed a mass effect on vascular structures, seven had cerebral venous sinus obstruction, and two had aneurysms. No iatrogenic accidents with the CT procedure were reported.

CONCLUSIONS

The 4D CTA technique is effective and safe for depicting vascular structures such as arteries, veins, tumor-related vessels, and direct and indirect anatomical complications such as vascular obstruction or vascular compression. This information is useful for preoperative screening. Although 4D CTA also provides perfusion data correlating with the tumor vascularity and grading of gliomas, its clinical value remains limited.

Accuracy of four-dimensional CT angiography in detection and characterisation of arteriovenous malformations and dural arteriovenous fistulas

A retrospective review was made to assess the accuracy of four dimensional CT angiogram (4D-CTA) in diagnosis of arteriovenous malformations (AVM) and dural arteriovenous fistulas (DAVF), with catheter-based digital-subtraction angiogram (DSA) being gold standard. 33 pairs of investigations (DSA and 4D-CTA) were performed primarily for suspicion of AVM/DAVF. Based on blinded reports, sensitivity and specificity for detection of AVM/DAVF were 77% (95% CI: 46-95%) and 100% (95% CI: 83-100%) respectively. Positive predictive value was 100% (95% CI: 69-100%) and negative predictive value 87% (95% CI: 66-97%). 4D-CTA is a practical minimally-invasive technique for evaluating cerebrovascular pathologies. There is good agreement between the findings of 4D-CTA and DSA despite the differences in temporal and spatial resolutions. 4D-CTA may obviate the need for DSA in a subgroup of patients who would otherwise have undergone this invasive investigation, which carries a risk of important complications.