[Magnetic resonance imaging of angiogenesis in tumors]

Accuracy and role of contrast-enhanced CT in diagnosis and surgical planning in 88 soft tissue tumours of extremities

OBJECTIVES

Soft tissue tumours (STT) require accurate diagnosis in order to identify potential malignancies. Preoperative planning is fundamental to avoid inadequate treatments. The role of contrast-enhanced computed tomography (CT) for local staging remains incompletely assessed. Aims of the study were to evaluate CT accuracy in discriminating active from aggressive tumours compared to histology and evaluate the role of CT angiography (CTA) in surgical planning.

MATERIALS AND METHODS

This retrospective cohort series of 88 cases from 1200 patients (7 %) was locally studied by contrast-enhanced CT and CTA in a referral centre: 74 malignant tumours, 14 benign lesions. Contrast-enhancement patterns and relationship of the mass with major vessels and bone were compared with histology on surgically excised samples. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) were evaluated in discriminating active from aggressive tumours.

RESULTS

Sensitivity in differentiating aggressive tumours from active lesions was 89 %, specificity 84 %, PPV 90 %, NPV 82 %. The relationship between mass and major vessels/bone was fundamental for surgical strategy respectively in 40 % and in 58 % of malignant tumours.

CONCLUSION

Contrast-enhanced CT and CTA are effective in differentiating aggressive masses from active lesions in soft tissue and in depicting the relationship between tumour and adjacent bones and major vessels.

KEY POINTS

• Accurate delineation of vascular and bony involvement preoperatively is fundamental for a correct resection. • CT plays a critical role in differential diagnosis of soft tissue masses. • Contrast-enhanced CT and CT angiography are helpful in depicting tumoral vascular involvement. • CT is optimal for characterization of bone involvement in soft tissue malignancies.

Perfusion pattern and time of vascularisation with CEUS increase accuracy in differentiating between benign and malignant tumours in 216 musculoskeletal soft tissue masses

INTRODUCTION

Musculoskeletal Soft Tissue Tumours (STT) are frequent heterogeneous lesions. Guidelines consider a mass larger than 5 cm and deep with respect to the deep fascia potentially malignant. Contrast Enhanced Ultrasound (CEUS) can detect both vascularity and tumour neoangiogenesis. We hypothesised that perfusion patterns and vascularisation time could improve the accuracy of CEUS in discriminating malignant tumours from benign lesions.

MATERIALS AND METHODS

216 STT were studied: 40% benign lesions, 60% malignant tumours, 56% in the lower limbs. Seven CEUS perfusion patterns and three types of vascularisation (arterial-venous uptake, absence of uptake) were applied. Accuracy was evaluated by comparing imaging with the histological diagnosis. Univariate and multivariate analysis, Chi-square test and t-test for independent variables were applied; significance was set at p<0.05 level, 95% computed CI.

RESULTS

CEUS pattern 6 (inhomogeneous perfusion), arterial uptake and location in the lower limb were associated with high risk of malignancy. CEUS pattern has PPV 77%, rapidity of vascularisation PPV 69%; location in the limbs is the most sensitive indicator, but NPV 52%, PPV 65%. The combination of CEUS-pattern and vascularisation has 74% PPV, 60% NPV, 70% sensitivity. No correlation with size and location in relation to the deep fascia was found.

CONCLUSION

US with CEUS qualitative analysis could be an accurate technique to identify potentially malignant STT, for which second line imaging and biopsy are indicated in Referral Centers. Intense inhomogeneous enhancement with avascular areas and rapid vascularisation time could be useful in discriminating benign from malignant SST, overall when the lower limbs are involved.

Contrast-enhanced ultrasonography of peripheral soft-tissue tumors: Feasibility study and preliminary results

OBJECTIVES

To determine the diagnostic value of contrast-enhanced ultrasonography, to differentiate benign and malignant soft-tissue tumors and to assess the feasibility and interest of modelling enhancement curves.

PATIENTS AND METHODS

This retrospective study includes 118 patients with soft-tissue tumors, examined with ultrasound after injection of SonoVue(®), a contrast product. The raw data were treated with CHI-Q acquisition software to model the enhancement curves. We analyzed tumor uptake of the contrast product visually and studied the enhancement curves, characterized by five parameters: peak intensity, time to peak, mean transit time, initial slope, and area under the curve.

RESULTS

There were 81 benign and 37 malignant tumors. For a diagnosis of benign tumor, the absence of contrast uptake had a sensitivity of 60%, a specificity of 68%, a positive predictive value of 50% and a negative predictive of 83%. Study of the 70 curves obtained (48 benign and 22 malignant tumors) showed that the parameters of area under the curve (Chi(2)=8.6 and P<0.005), slope (Chi(2)=8.12 and P=0.004), and peak intensity (Chi(2)=7.55, P=0.005) differed significantly between the two populations.

CONCLUSION

Absence of contrast uptake suggests a benign lesion. The study of enhancement curves showed significant differences between the different tumor populations.

[Diffusion-weighted MR imaging of liver pathology: principles and clinical applications]

Due to ongoing technological advances, the range of clinical applications for diffusion-weighted MR imaging has expanded to now include abdominal pathology. Current applications for liver pathology include two main directions. First, oncologic imaging with detection, characterization and follow-up of lesions. Second, evaluation of diffuse liver diseases, including hepatic fibrosis. The diagnostic impact and role of diffusion-weighted MR imaging remain under investigation, but appear promising. Because of its short acquisition time, sensitivity, and additional information it provides, diffusion-weighted MR imaging should be included in routine liver imaging protocols.

Free-breathing diffusion-weighted single-shot echo-planar MR imaging using parallel imaging (GRAPPA 2) and high b value for the detection of primary rectal adenocarcinoma

Our objective was to determine the diagnostic accuracy of a free-breathing diffusion-weighted single-shot echo-planar magnetic resonance imaging (FBDW-SSEPI) technique with parallel imaging and high diffusion factor value (b = 1000 s/mm²) in the detection of primary rectal adenocarcinomas. Thirty-one patients (14M and 17F; mean age 67 years) with histopathologically proven primary rectal adenocarcinomas and 31 patients without rectal malignancies (14M and 17F; mean age 63.6 years) were examined with FBDW-SSEPI (repetition time (TR/echo time (TE) 3900/91 ms, gradient strength 45 mT/m, acquisition time 2 min) at 1.5 T using generalized autocalibrating partially parallel acquisitions (GRAPPA, acceleration factor 2) and a b value of 1000 s/mm². Apparent diffusion coefficients (ADCs) of rectal adenocarcinomas and normal rectal wall were measured. FBDW-SSEPI images were evaluated for tumour detection by 2 readers. Sensitivity, specificity, accuracy and Youden score for rectal adenocarcinoma detection were calculated with their 95% confidence intervals (CI) for ADC value measurement and visual image analysis. Rectal adenocarcinomas had significantly lower ADCs (mean 1.036 × 10⁻³± 0.107 × 10⁻³ mm²/s; median 1.015 × 10⁻³ mm²/s; range (0.827–1.239) × 10⁻³ mm²/s) compared with the rectal wall of control subjects (mean 1.387 × 10⁻³± 0.106 × 10⁻³ mm²/s; median 1.385 × 10⁻³ mm²/s; range (1.176–1.612) × 10⁻³ mm²/s) (p < 0.0001). Using a threshold value ≤ 1.240 × 10⁻³ mm²/s, all rectal adenocarcinomas were correctly categorized and 100% sensitivity (31/31; 95% CI 95–100%), 94% specificity (31/33; 95% CI 88–100%), 97% accuracy (60/62; 95% CI 92–100%) and Youden index 0.94 were obtained for the diagnosis of rectal adenocarcinoma. FBDW-SSEPI image analysis allowed depiction of all rectal adenocarcinomas but resulted in 2 false-positive findings, yielding 100% sensitivity (31/31; 95% CI 95–100%), 94% specificity (31/33; 95% CI 88–100%), 97% accuracy (60/62; 95% CI 92–100%) and Youden index 0.94 for the diagnosis of primary rectal adenocarcinoma. We can conclude that FBDW-SSEPI using parallel imaging and high b value may be helpful in the detection of primary rectal adenocarcinomas.

Vascular changes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most vascular solid tumors, in which angiogenesis plays an important role. The status of angiogenesis in HCC correlates with the disease progression and prognosis, and thus provides a potential therapeutic target. This review summarizes the vascular changes and molecular and cellular basis of angiogenesis in HCC. Development of HCC is characterized by arterialization of its blood supply and sinusoidal capillarization. Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that plays a critical role in mediating angiogenesis in HCC. The VEGF can function on various types of cells, such as endothelial cells, hepatic stellate cells, endothelial progenitor cells and hemangiocytes, to induce vascular changes in HCC. Therefore, blockade of VEGF-mediated pathways, either by anti-VEGF neutralizing antibody or tyrosine kinase inhibitors that target VEGF receptors, suppresses carcinogenesis and angiogenesis in HCC. In addition to VEGF, several other angiogenic factors in HCC have recently been identified. These factors can also regulate angiogenic processes through interaction with VEGF or VEGF-independent pathways. Despite the fact that treatment of HCC remains a tough task due to lack of effective systemic therapy, antiangiogenic therapy has already entered clinical trials in HCC patients and sheds light on a promising novel treatment for this disease.