CT Angiography: Post-processed Contrast Enhancement for Improved Detection of Pulmonary Embolism.

RATIONALE AND OBJECTIVES: The study aimed to improve the detection of pulmonary embolism via an iodine contrast enhancement tool in patients who underwent suboptimal enhanced computed tomography angiography (CTA). MATERIALS AND METHODS: We evaluated the CT examinations of 41 patients who underwent CTA for evaluation of the pulmonary arteries which suffered from suboptimal contrast enhancement. The contrast enhancement of the reconstructed images was increased via a post-processing tool (vContrast). Image noise and contrast-to-noise ratio (CNR) were assessed in eight different regions: main pulmonary artery, right and left pulmonary arteries, right and left segment arteries, muscle, subcutaneous fat, and bone. For subjective image assessment, three experienced radiologists evaluated the diagnostic quality. RESULTS: While employing the post-processing algorithm, the CNR for contrast-filled lumen and thrombus/muscle improves significantly by a factor of 1.7 (CNR without vContrast = 8.48 ± 6.79/CNR with vContrast = 14.46 ± 5.29) (P <0.01). No strengthening of artifacts occurred, and the mean Hounsfield unit values of the muscle, subcutaneous fat, and the bone showed no significant changes. Subjective image analysis illustrated a significant improvement using post-processing for clinically relevant criteria such as diagnostic confidence. CONCLUSIONS: vContrast makes CT angiograms with inadequate contrast applicable for diagnostic evaluation, offering an improved visualization of the pulmonary arteries. In addition, vContrast can help in the significant reduction of the iodine contrast material.

Influence of Sorafenib and Bevacizumab on pancreatic volume - A monocentric CT based analysis.

BACKGROUND/OBJECTIVES: Angiogenesis plays a central role in tumor growth and metastasis and tyrosine kinases are crucial in the modulation of growth factor signaling. Several side effects of tyrosine kinase inhibitors have been reported, including diarrhea due to pancreatic insufficiency. The suspected mechanism is the anti-angiogenetic effect of the inhibited vascular endothelial growth factor (VEGF) causing a disturbance of the microvasculation. The aim of the present study was to determine the volume of the pancreas before and after a therapy both with the multi-tyrosine kinase inhibitor Sorafenib and Bevacizumab, which is a humanized monoclonal immunoglobulin G1 antibody against VEGF. METHODS: Retrospective monocentric study including 42 patients who received either Sorafenib, Bevacizumab combined with Flourouracil and/or Irinotecan, or singly Flourouracil and Irinotecan for different non-pancreatic malignancies. The volume of the pancreas was measured before and after therapy by CT-scan based volumetry. RESULTS: The pancreatic volume was statistically significantly lower after treatment with Sorafenib (75.4 mL vs. 71.0 mL; p = 0.006) or Bevacizumab and Fluorouracil ± Irinotecan (71.8 mL vs. 62.6 mL; p = 0.020). The pancreatic volume did not change statistically significantly after treatment with Fluorouracil ± Irinotecan only (51.1 mL vs. 49.9 mL; p = 0.142). CONCLUSIONS: Pancreatic volume decreases statistically significantly under treatment with both the multi-tyrosine kinase inhibitor Sorafenib and the angiogenesis inhibitor Bevacizumab. This volume reduction is most likely due to a reduced microvasculation by inhibition of VEGF.

Evaluation of Computed Tomography for Lymph Node Staging in Bladder Cancer Prior to Radical Cystectomy.

OBJECTIVES: To retrospectively evaluate the value of CT for lymph node (LN) staging in bladder cancer. METHODS: Two uroradiologists reviewed CT scans of 231 patients who underwent radical cystectomy and pelvic lymphadenectomy according to a predefined 12-field template. A 5-step model was used to grade the radiological likelihood of a LN to represent malignant spread based on size, configuration and structure as well as regional clustering. Statistical analyses were performed both on patient- and field-based levels. RESULTS: LN metastases were found in 59 of 231 patients (25.5%). On a patient-based level, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were 52.6, 93.6, 73.2, 85.6 and 83.4%, respectively. Using the field-based approach, a total of 1,649 anatomical fields were evaluable, of which 114 fields showed malignancy (6.9%). On a field basis, sensitivity, specificity, PPV, NPV and accuracy were 30.2, 98, 51.5, 94.5 and 93.3%, respectively. Concerning local staging (pT category), the overall accuracy was 78%; overstaging occurred in 6% and understaging in 16%. CONCLUSIONS: In line with prior studies, the sensitivity of CT imaging for the detection of LN metastases was low, while high values for specificity were achieved. This was further underlined by analyzing standardized anatomical fields. Concerning local staging, postoperative changes after TURB-T rarely led to overstaging.

Prognostic value of computed tomography before radical cystectomy in patients with invasive bladder cancer: imaging predicts survival.

PURPOSE: Computed tomography (CT) is current standard-of-care for preoperative staging in patients with invasive bladder cancer before radical cystectomy (RC). There are only sparse data on the association between preoperative CT findings and postoperative survival of patients. METHODS: We retrospectively evaluated preoperative CTs of 206 patients with invasive bladder cancer undergoing RC in an academic tertiary referral center. CTs were analyzed retrospectively for relative bladder wall thickness (BWT) and size of lymph nodes (LN). Associations between CT findings and risk of death from any cause (AC) as well as risk of death from bladder cancer (BC) were assessed by Kaplan-Meier estimates, cumulative incidence curves and multivariable Cox regression analysis. RESULTS: The median follow-up was 40 months. Increased BWT was significantly correlated with higher risk of death (AC: HR 1.68; p = 0.043; BC: HR 2.00; p = 0.027), as well as LN with a size of 6-10 mm (AC: HR 2.13; p = 0.002; BC: HR 2.77; p = 0.002) and >10 mm (AC: HR 2.47; p = 0.018; BC: HR 3.66; p = 0.007) when compared to LN ≤ 5 mm. CONCLUSION: Our data showed a significant correlation of bladder wall thickness and LN size with the risk of death. Also lymph nodes >5 mm but ≤ 10 mm (resp. ≤ 8 mm)-usually considered non-pathologic-were associated with a significantly worse prognosis. This information can be used to counsel patients preoperatively. It might also be useful for a risk-adapted approach in regard to neoadjuvant chemotherapy.

Volumetric gain of the human pancreas after left partial pancreatic resection: A CT-scan based retrospective study.

BACKGROUND/OBJECTIVES: Regeneration of the pancreas has been well characterized in animal models. However, there are conflicting data on the regenerative capacity of the human pancreas. The aim of the present study was to assess the regenerative capacity of the human pancreas. METHODS: In a retrospective study, data from patients undergoing left partial pancreatic resection at a single center were eligible for inclusion (n = 185). Volumetry was performed based on 5 mm CT-scans acquired through a 256-slice CT-scanner using a semi-automated software. RESULTS: Data from 24 patients (15 males/9 females) were included. Mean ± SD age was 68 ± 11 years (range, 40-85 years). Median time between surgery and the 1st postoperative CT was 9 days (range, 0-27 days; IQR, 7-13), 55 days (range, 21-141 days; IQR, 34-105) until the 2nd CT, and 191 days (range, 62-1902; IQR, 156-347) until the 3rd CT. The pancreatic volumes differed significantly between the first and the second postoperative CT scans (median volume 25.6 mL and 30.6 mL, respectively; p = 0.008) and had significantly increased further by the 3rd CT scan (median volume 37.9 mL; p = 0.001 for comparison with 1st CT scan and p = 0.003 for comparison with 2nd CT scan). CONCLUSIONS: The human pancreas shows a measurable and considerable potential of volumetric gain after partial resection. Multidetector-CT based semi-automated volume analysis is a feasible method for follow-up of the volume of the remaining pancreatic parenchyma after partial pancreatectomy. Effects on exocrine and endocrine pancreatic function have to be evaluated in a prospective manner.

Osteoporosis imaging: effects of bone preservation on MDCT-based trabecular bone microstructure parameters and finite element models.

BACKGROUND: Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength due to a reduction of bone mass and deterioration of bone microstructure predisposing an individual to an increased risk of fracture. Trabecular bone microstructure analysis and finite element models (FEM) have shown to improve the prediction of bone strength beyond bone mineral density (BMD) measurements. These computational methods have been developed and validated in specimens preserved in formalin solution or by freezing. However, little is known about the effects of preservation on trabecular bone microstructure and FEM. The purpose of this observational study was to investigate the effects of preservation on trabecular bone microstructure and FEM in human vertebrae. METHODS: Four thoracic vertebrae were harvested from each of three fresh human cadavers (n=12). Multi-detector computed tomography (MDCT) images were obtained at baseline, 3 and 6 month follow-up. In the intervals between MDCT imaging, two vertebrae from each donor were formalin-fixed and frozen, respectively. BMD, trabecular bone microstructure parameters (histomorphometry and fractal dimension), and FEM-based apparent compressive modulus (ACM) were determined in the MDCT images and validated by mechanical testing to failure of the vertebrae after 6 months. RESULTS: Changes of BMD, trabecular bone microstructure parameters, and FEM-based ACM in formalin-fixed and frozen vertebrae over 6 months ranged between 1.0-5.6% and 1.3-6.1%, respectively, and were not statistically significant (p>0.05). BMD, trabecular bone microstructure parameters, and FEM-based ACM as assessed at baseline, 3 and 6 month follow-up correlated significantly with mechanically determined failure load (r=0.89-0.99; p<0.05). The correlation coefficients r were not significantly different for the two preservation methods (p>0.05). CONCLUSIONS: Formalin fixation and freezing up to six months showed no significant effects on trabecular bone microstructure and FEM-based ACM in human vertebrae and may both be used in corresponding in-vitro experiments in the context of osteoporosis.

Validation of a low dose simulation technique for computed tomography images.

PURPOSE: Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan. MATERIALS AND METHODS: Original CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV) of a swine were acquired (approved by the regional governmental commission for animal protection). Simulations of CT acquisition with a lower dose (simulated 10-80 mAs) were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images. RESULTS: Image characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was -1.2% (range -9% to 3.2%) and -0.2% (range -8.2% to 3.2%), respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9-10.2 HU (noise) and 1.9-13.4 HU (CT values), without significant differences (p>0.05). Subjective observer evaluation of image appearance showed no visually detectable difference. CONCLUSION: Simulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques.

Rapid assessment of liver volumetry by a novel automated segmentation algorithm.

OBJECTIVE: This study aimed to evaluate a novel segmentation software for automated liver volumetry and segmentation regarding segmentation speed and interobserver variability. METHODS: Computed tomographic scans of 20 patients without underlying liver disease and 10 patients with liver metastasis from colorectal cancer were analyzed by a novel segmentation software. Liver segmentation was performed after manual placement of specific landmarks into 9 segments according to the Couinaud model as well as into 4 segments, the latter being import for surgery planning. Time for segmentation was measured and the obtained segmental and total liver volumes between the different readers were compared calculating intraclass correlations (ICCs). Volumes of liver tumor burden were evaluated similarly. RESULTS: Liver segmentation could be performed rapidly 3 minutes or less. Comparison of total liver volumes revealed a perfect ICC of greater than 0.997. Segmental liver volumes within the 9-part segmentation provided fair to moderate correlation for the left lobe and good to excellent correlations for the right lobe. When applying a 4-part segmentation relevant to clinical practice, strong to perfect agreement was observed. Similarly tumor volumes showed perfect ICC (>0.998). CONCLUSIONS: Rapid determination of total and segmental liver volumes can be obtained using a novel segmentation software suitable for daily clinical practice.

Phenotyping of pulmonary carcinoids and a Ki-67-based grading approach.

Pulmonary carcinoids (PC) are separated into typical (TC) and atypical carcinoids (ATC). However, the biological behavior cannot be reliably predicted, and in small biopsies differential diagnosis can be challenging. To provide a basis for a grading approach, we analyzed mitoses and the proliferative index (PI; Ki-67) of 200 PC specimens (TC: n = 114; ATC: n = 86). To define suitable diagnostic and to screen for putative therapeutic markers, CD56, CD57, CD99, CD117, TTF-1, synaptophysin, chromogranin A, CK 18, KL-1, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (Her-2/neu), somatostatin receptor subtype 2A (SSTR2A), thymidylate synthase (TS), and excision repair cross-complementation group 1 (ERCC-1) expression was analyzed. A combination of synaptophysin and cytokeratins is the most sensitive marker panel for PC with unclear histomorphology. Predictive phenotyping revealed that SSTR2A is expressed in >80% of all PC and may be used both, as a diagnostic marker for imaging approaches and as a predictive marker for octreotide-based therapies. We introduced a grading system distinguishing between PC with low and highly aggressive biological behavior similar to the grading system for gastrointestinal neuroendocrine tumors. The system is superior to the classical separation into TC and ATC. This study indicates that PI in addition to mitotic count may improve prediction of the biological behavior of PC and should be validated in prospective studies.

Her2 overexpression is a rare event in anorectal melanoma.

Anorectal melanomas (AMs) are very rare and highly malignant tumors that are often diagnosed in advanced stages. After the differentiation between cutaneous melanoma (CM) and AM on the molecular level based on the presence of BRAF mutations, further modes of differentiation opened up, such as the recently discovered immunohistologically relevant protein deleted in malignant brain tumors 1 (DMBT1). Over the past several years, increasingly specific therapies have been developed on the basis of new therapy principles. Tyrosin kinase receptors such as Her2 and EGFR have been awarded a large role in this context. The goal of this study was to examine AMs for a possible expression or overexpression of these markers. Expression analyses of Her2 and EGFR were performed immunohistologically on 25 primary AMs. An overexpression of Her2 (score: 3+) was found in one AM from a 68-year-old female patient among these samples. In contrast, EGFR expression was not found in any of the AMs. The results presented here show that isolated cases of AM may benefit from an additive Her2-directed therapy, as the overexpression of Her2 was found in one of our AM patients.