Apparent Diffusion Coefficient Quantification in Determining the Histological Diagnosis of Malignant Liver Lesions.

PURPOSE: Diffusion Weighted Imaging is an established diagnostic tool for accurate differential diagnosis between benign and malignant liver lesions. The aim of our study was to evaluate the role of Histogram Analysis of ADC quantification in determining the histological diagnosis as well as the grade of malignant liver tumours. To our knowledge, there is no study evaluating the role of Histogram Analysis of ADC quantification in determining the histological diagnosis as well as the grade of malignant liver tumours. METHODS: During five years, 115 patients with known liver lesions underwent Diffusion Weighted Imaging in 3Tesla MR scanner prior to core needle biopsy. Histogram analyses of ADC in regions of interest were drawn and were correlated with biopsy histological diagnosis and grading. RESULTS: Histogram analysis of ADC values shows that 5th and 30th percentile parameters have statistically significant potency of discrimination between primary and secondary lesions groups (p values 0.0036 and 0.0125 respectively). Skewness of the histogram can help discriminate between good and poor differentiated (p value 0.17). Discrimination between primary malignancy site in metastases failed for the present number of patients in each subgroup. CONCLUSION: Statistical parameters reflecting the shape of the left side of the ADC histogram can be useful for discriminating between primary and secondary lesions and also between well differentiated versus moderate or poor. For the secondary malignancies, they failed to predict the original site of tumour.

Gastrointestinal stromal tumors: a pictorial review.

We describe the pertinent organ-specific clinical manifestations of gastrointestinal stromal tumors (GISTs) as well as the radiological appearances that allow optimal depiction of pathology and diagnosis. Radiologic features of GISTs vary depending on tumor size and organ of origin. They most commonly have an exophytic growth pattern and manifest as dominant masses outside the organ of origin. Intramural and intraluminal masses are less common radiologic manifestations. GISTs may contain areas of hemorrhage, necrosis, or cyst formation that appear as focal areas of low attenuation on computed tomographic images. Most metastases of GISTs involve the liver and peritoneum by hematogenous spread and peritoneal seeding. CT and MRI are considered to be the imaging modality of choice for the detection, staging, surgical planning and follow-up of patients with GIST. A reduction in tumor size, extensive cystic changes, and calcification in primary and metastatic GISTs on CT and MRI indicate disease response to therapy. Radiologists and clinicians must recognize the imaging features of GISTs, detect, characterize the lesions and evaluate the tumor response during specific treatment.