Sofia Gourtsoyianni

Spectral CT with Metal Artifacts Reduction Software for Improvement of Tumor Visibility in the Vicinity of Gold Fiducial Markers

PURPOSE To evaluate spectral computed tomography (CT) with metal artifacts reduction software (MARS) for reduction of metal artifacts associated with gold fiducial seeds. MATERIALS AND METHODS Thirteen consecutive patients with 37 fiducial seeds implanted for radiation therapy of abdominal lesions were included in this HIPAA-compliant, institutional review board-approved prospective study. Six patients were women (46%) and seven were men (54%). The mean age was 61.1 years (median, 58 years; range, 29-78 years). Spectral imaging was used for arterial phase CT. Images were reconstructed with and without MARS in axial, coronal, and sagittal planes. Two radiologists independently reviewed reconstructions and selected the best image, graded the visibility of the tumor, and assessed the amount of artifacts in all planes. A linear-weighted κ statistic and Wilcoxon signed-rank test were used to assess interobserver variability. Histogram analysis with the Kolmogorov-Smirnov test was used for objective evaluation of artifacts reduction. RESULTS Fiducial seeds were placed in pancreas (n = 5), liver (n = 7), periportal lymph nodes (n = 1), and gallbladder bed (n = 1). MARS-reconstructed images received a better grade than those with standard reconstruction in 60% and 65% of patients by the first and second radiologist, respectively. Tumor visibility was graded higher with standard versus MARS reconstruction (grade, 3.7 ± 1.0 vs 2.8 ± 1.1; P = .001). Reduction of blooming was noted on MARS-reconstructed images (P = .01). Amount of artifacts, for both any and near field, was significantly smaller on sagittal and coronal MARS-reconstructed images than on standard reconstructions (P < .001 for all comparisons). Far-field artifacts were more prominent on axial MARS-reconstructed images than on standard reconstructions (P < .01). Linear-weighted κ statistic showed moderate to perfect agreement between radiologists. CT number distribution was narrower with MARS than with standard reconstruction in 35 of 37 patients (P < .001). CONCLUSION Spectral CT with use of MARS improved tumor visibility in the vicinity of gold fiducial seeds.

Split-bolus spectral multidetector CT of the pancreas: assessment of radiation dose and tumor conspicuity.

PURPOSE To assess tumor conspicuity and radiation dose with a new multidetector computed tomography (CT) protocol for pancreatic imaging that combines spectral CT and split-bolus injection. MATERIALS AND METHODS This study was approved by the institutional review board and compliant with HIPAA. The requirement for informed consent was waived. One hundred sixty-three consecutive patients referred for possible pancreatic mass underwent CT with either a standard or split-bolus spectral CT protocol depending on scanner availability. Split-bolus spectral CT (CT unit with spectral imaging) combines pancreatic and portal venous phases in a single scan: 70 seconds before CT, 100 mL of contrast material is injected for the portal venous phase followed approximately 35 seconds later by injection of 40 mL of contrast material to boost the pancreatic phase. Bolus tracking after the second bolus initiates scanning 15 seconds after aorta enhancement reaches 280 HU. Images were reconstructed at 60 and 77 keV. The standard protocol (64-detector row unit) included unenhanced and pancreatic and portal venous phase imaging, with a single contrast material injection timed with bolus tracking 15 seconds after aortic enhancement of 300 HU for the pancreatic phase and 32 seconds later for the portal venous phase. Tumor conspicuity (difference in attenuation between tumor and pancreatic parenchyma) and contrast-to-noise ratio (CNR) were determined. Attenuation of aorta, main portal vein, and liver were measured. Patient size and per-examination radiation dose were recorded. The heteroscedastic t test, Fisher exact test, and Mann-Whitney test were used for statistical analysis. RESULTS There were no significant differences in age, weight, and body mass index between patients in the standard CT (46 of 80 patients had lesions) and split-bolus spectral CT (39 of 83 patients had lesions) groups; however, there were significantly more women in the split-bolus group (P = .02). Tumor conspicuity and CNR were higher with the 60-keV split-bolus protocol (89.1 HU ± 56.6 and 8.8 ± 6.2, respectively) than with the pancreatic or portal venous phase of the standard protocol (43.5 HU ± 28.4 and 4.5 ± 3.0, and 51.5 HU ± 30.3 and 5.6 ± 4.0, respectively; P < .01 for all comparisons). Dose-length product was 1112 mGy · cm ± 437 with the standard protocol and 633 mGy · cm ± 105 with the split-bolus protocol (P < .001). CONCLUSION Split-bolus spectral multidetector CT resulted in vascular, liver, and pancreatic attenuation and tumor conspicuity equal to or greater than that with multiphase CT, with a 43% reduction in radiation dose.

Rectal tumour volume (GTV) delineation using T2-weighted and diffusion-weighted MRI: Implications for radiotherapy planning.

PURPOSE To compare the rectal tumour gross target volume (GTV) delineated on T2 weighted (T2W MRI) and diffusion weighted MRI (DWI) images by two different observers and to assess if agreement is improved by DWI. MATERIAL AND METHODS 27 consecutive patients (15 male, range 27.1-88.8 years, mean 66.9 years) underwent 1.5T MRI prior to chemoradiation (45Gy in 25 fractions; oral capecitabine 850mg/m(2)), including axial T2W MRI (TR=6600ms, TE=90ms) and DWI (TR=3000ms, TE=77ms, b=0, 100, 800s/mm(2)). 3D tumour volume (cm(3)) was measured by volume of interest (VOI) analysis by two independent readers for the T2W MRI and b800 DWI axial images, and the T2W MRI and DWI volumes compared using Mann-Whitney test. Observer agreement was assessed using Bland-Altman statistics. Significance was at 5%. RESULTS Artefacts precluded DWI analysis in 1 patient. In the remaining 26 patients evaluated, median (range) T2W MRI MRI and DWI (b=800s/mm(2)) 3D GTVin cm(3) were 33.97 (4.44-199.8) and 31.38 (2.43-228), respectively, for Reader One and 43.78 (7.57-267.7) and 42.45 (3.68-251) for Reader Two. T2W MRI GTVs were slightly larger but not statistically different from DWI volumes: p=0.52 Reader One; p=0.92 Reader Two. Interobserver mean difference (95% limits of agreement) for T2W MRI and DWI GTVs were -9.84 (-54.96 to +35.28) cm(3) and -14.79 (-54.01 to +24.43) cm(3) respectively. CONCLUSION Smaller DWI volumes may result from better tumour conspicuity but overall observer agreement is not improved by DWI.

Routine use of modified CT Enterography in patients with acute abdominal pain

PURPOSE To evaluate routine use of CT Enterography (CTE) in patients presenting with non-traumatic acute abdominal pain with respect to patient tolerance, imaging of intestinal detail along with conventional abdominal evaluation. MATERIALS AND METHODS Modified CTE was performed in 165 consecutive patients with acute abdominal pain: ingestion, as tolerated, of 900-1200 ml of 2% barium suspension + 5 ml of Gastrografin over 45 min; 150 ml of iv contrast given in two boluses (50 and 100 ml) 3 min apart (split bolus injection protocol). Axial, coronal and sagittal reformats were reviewed by two radiologists and graded on a 5-point scale (5 best) in regard to GI tract luminal opacification and distension and abdominal organ and vascular enhancement. RESULTS In 81 patients the cause of abdominal pain was identified (intestinal in 54 and extraintestinal in 27). Oral contrast reached cecum in 76% of the patients and the small bowel was well distended and opacified (medians=4). Mucosa detail was good (median=3) and there was significant (p<0.0001) correlation between bowel opacification and distension for both jejunum and ileum. A combined nephrographic and excretory phase was achieved (medians 4 and 5, respectively), while the great vessels were well opacified, allowing for vascular evaluation (median=5). The rest of the abdominal structures were well visualized. CONCLUSION Modified CTE is well tolerated by patients with acute non-traumatic abdominal pain, and can be used routinely as a non-invasive examination informative of bowel, vessel and organ pathology in Emergency Department patients.

Functional imaging of the liver.

Anatomical-based imaging is used widely for the evaluation of diffuse and focal liver, including detection, characterization, and therapy response assessment. However, a limitation of anatomical-based imaging is that structural changes may occur relatively late in a disease process. By applying conventional anatomical-imaging methods in a more functional manner, specific pathophysiologic alterations of the liver may be assessed and quantified. There has been an increasing interest in both the clinical and research settings, with the expectation that functional-imaging techniques may help solve common diagnostic dilemmas that conventional imaging alone cannot. This review considers the most common functional magnetic resonance imaging, computed tomography, and ultrasound imaging techniques that may be applied to the liver.

CT-guided core biopsy and percutaneous fiducial seed placement in the lung: Can these procedures be combined without an increase in complication rate or decrease in technical success?

OBJECTIVE To determine if concomitant CT-guided biopsy and percutaneous fiducial seed placement in the lung can be performed in a selective patient population without increased complication or decreased success rates compared to either procedure alone. MATERIALS AND METHODS An IRB approved retrospective analysis of 285 consecutive patients that underwent CT-guided placement of fiducial seeds in the lung alone (N=63), with concomitant core biopsy (N=53) or only core biopsy (N=169) was performed. Variables compared included: patient demographics, lesion size, depth from pleura, needle size, number of passes through pleura, number and size of core biopsies, number of seeds placed and technical success rates. Statistical analysis was performed using univariate and multivariate pair-wise comparisons. RESULTS A pathologic diagnosis of malignancy was confirmed in all cases undergoing seed placement alone and seed placement with concurrent biopsy, and in 144 of the biopsy alone lesions. On univariate analysis, major complication rates were similar for all three groups as were lesion size, depth, number of pleural passes, and technical success. Pair-wise comparisons of the remaining variables demonstrated a significant younger age and smaller needle size in the biopsy only group, and less minor complications in the fiducial only group. Overall there were 80/285 (28.1%) minor and 29/285 (10.2%) major complications. All major complications leading to admission consisted of either pneumothorax or hemothorax, while minor complications included asymptomatic stable or resolving pneumothoraces, transient hemoptysis or small hemothoraces. CONCLUSIONS A combined procedure of percutaneous pulmonary core biopsy and stereotactic seed placement can be performed without additional risk of a major complication when compared to performing these separately.

Primary Rectal Cancer: Repeatability of Global and Local-Regional MR Imaging Texture Features

Purpose To assess the day-to-day repeatability of global and local-regional magnetic resonance (MR) imaging texture features derived from primary rectal cancer. Materials and Methods After ethical approval and patient informed consent were obtained, two pretreatment T2-weighted axial MR imaging studies performed prospectively with the same imaging unit on 2 consecutive days in 14 patients with rectal cancer (11 men [mean age, 61.7 years], three women [mean age, 70.0 years]) were analyzed to extract (a) global first-order statistical histogram and model-based fractal features reflecting the whole-tumor voxel intensity histogram distribution and repeating patterns, respectively, without spatial information and (b) local-regional second-order and high-order statistical texture features reflecting the intensity and spatial interrelationships between adjacent in-plane or multiplanar voxels or regions, respectively. Repeatability was assessed for 46 texture features, and mean difference, 95% limits of agreement, within-subject coefficient of variation (wCV), and repeatability coefficient (r) were recorded. Results Repeatability was better for global parameters than for most local-regional parameters. In particular, histogram mean, median, and entropy, fractal dimension mean and standard deviation, and second-order entropy, homogeneity, difference entropy, and inverse difference moment demonstrated good repeatability, with narrow limits of agreement and wCVs of 10% or lower. Repeatability was poorest for the following high-order gray-level run-length (GLRL) gray-level zone size matrix (GLZSM) and neighborhood gray-tone difference matrix (NGTDM) parameters: GLRL intensity variability, GLZSM short-zone emphasis, GLZSM intensity nonuniformity, GLZSM intensity variability, GLZSM size zone variability, and NGTDM complexity, demonstrating wider agreement limits and wCVs of 50% or greater. Conclusion MR imaging repeatability is better for global texture parameters than for local-regional texture parameters, indicating that global texture parameters should be sufficiently robust for clinical practice. Online supplemental material is available for this article.

Current Status of Interventional Radiology in the Management of Gastro-Entero-Pancreatic Neuroendocrine Tumours (GEP-NETs)

Within the group of Gastro-Entero-Pancreatic Neuroendocrine tumours (GEP-NETs), several heterogeneous malignancies are included with a variety of clinical manifestations and imaging characteristics. Often these cases are inoperable and minimal invasive treatment offered by image-guided procedures appears to be the only option. Interventional radiology offers a valid solution in the management of primary and metastatic GEP-NETs. The purpose of this review article is to describe the current status of the role of Interventional Radiology in the management of GEP-NETs.

The impact of MRI sequence on tumour staging and gross tumour volume delineation in squamous cell carcinoma of the anal canal

ObjectivesTo compare maximum tumour diameter (MTD) and gross tumour volume (GTV) measurements between T2-weighted (T2-w) and diffusion-weighted (DWI) MRI in squamous cell carcinoma of the anal canal (SCCA) and assess sequence impact on tumour (T) staging. Second, to evaluate interobserver agreement and reader delineation confidence.MethodsThe staging MRI scans of 45 SCCA patients (25 females) were assessed retrospectively by two independent radiologists (0 and 5 years’ experience of anal cancer MRI). MTD and GTV were delineated on both T2-w and high-b-value DWI images and compared between sequences; T staging was derived from MTD. Interobserver agreement was assessed and delineation confidence scored (1 to 5) by each observer.ResultsGTV and MTD were significantly and systematically lower on DWI versus T2-w sequences by 14.80%/9.98% (MTD) and 29.70%/12.25% (GTV) for each reader, respectively, causing T staging discordances in approximately a quarter of cases. Bland-Altman limits of agreement were narrower and intraclass correlation coefficients higher for DWI. Delineation confidence was greater on DWI: 40/42 cases were scored confidently (4 or 5) by each reader, respectively, versus 31/36 cases based on T2-w images.ConclusionsSequence selection affects SCCA measurements and T stage. DWI yields higher interobserver agreement and greater tumour delineation confidence.Key Points• MTD and GTV measurements are significantly lower on DWI than on T2-w MRI.• Such differences cause T staging discordances in up to a quarter of cases.• DWI results in higher agreement between inexperienced and experienced observers.• DWI offers greater tumour delineation confidence to inexperienced readers.

Value of customized scan timing determined by tracking liver enhancement in oncology patients.

Purpose: To assess the value of liver parenchyma enhancement tracking for liver multidetector computed tomography (CT) in patients with potential hypoattenuating liver metastases. Materials and Methods: Institutional review board approved this Health Insurance Portability and Accountability Act-compliant study. We reviewed the chest-abdomen-pelvis CTs of 120 consecutive patients scanned on 16-/64-row multidetector CT after receiving 52 g I in 50 seconds. Liver scanning started 65 seconds after injection-start in 59 patients, whereas in 61 patients, scanning started automatically when liver enhancement reached 50 Hounsfield units on low-dose continuous attenuation tracking. Enhancement of liver parenchyma, aorta, portal, and hepatic veins was measured. Two readers graded conspicuity and recorded attenuation of hypoattenuating lesions. Results: We identified 663 metastases in 74 patients. Scan-delay range in the triggered group was 53 to 83 seconds. Compared with the fixed-delay group, in the triggered group, mean number of metastases per patient with metastases was larger, liver attenuation and enhancement were higher, and median metastasis conspicuity grade was higher (all P < 0.05). Conclusions: Automatic scan triggering based on liver parenchyma enhancement tracking produces consistently higher liver parenchymal enhancement and increased metastasis conspicuity than fixed delay.