RESUMEN
Background: Superparamagnetic iron oxide (SPIO) is a new paramagnetic contrast agent used to distinguish benign and malignant hepatic tumors on magnetic resonance imaging (MRI). Objective: This prospective study was designed to compare detectability of malignant hepatic tumors using gadolinium (Gd) versus SPIO-enhanced (MRI). Methods: We selected fifteen patients suspected of malignant hepatic tumors of less than 5 cm in size. They included hepatocellular carcinoma (HCC) and hepatic metastasis. A dynamic Gd-enhanced study was performed first and followed by SPIO-enhanced study with time interval of 4 hours to one week. We performed fast spin echo T2 weighted image (FSE T2WI) with fat suppression, fast multiplana gradient echo T2* weighted image (FMPGR T2*WI), and single-shot FSE T2WI with fat suppression on SPIO study. All lesions were confirmed by histopathology, high Alpha fetoprotein level or follow up imaging. Both studies were analyzed by two independent radiologists. Results: The study included 11 cases (6 HCCs and 5 metastases). Four cases of benign lesions and unconfirmed diagnosis were excluded (2 cases of regenerating nodules and 2 cases of unconfirmed diagnosis). Range of sizes was 0.5-7.5 cm (mean = 2.0 cm). In quantitative analysis, SPIO could detect higher numbers of lesions compared with Gd, especially for small lesions (≤ 2 cm) and for HCCs. There was no difference between SPIO and Gd for detection of large malignant lesions (\>2 cm). Gd-enhanced MRI was better than SPIO for detection of the numbers of hepatic metastases. SPIO showed better imaging quality compared to Gd and the best MR sequence was FMPGR T2*WI. Conclusion: SPIO-enhanced MRI was superior to Gd-enhanced MRI for detection of small HCC, whereas Gd-enhanced MRI was better for detection of small hepatic metastases.
RESUMEN
Background: Aortic dissection is a common cause of vascular emergency. For examination of the entire aorta, multi-slice computed tomographic (CT) scanning is now used as the modality of choice instead of aortography. However, it was questionable whehter CT angiography (CTA) can be used for management decisions regarding aortic dissection. Objective: To prove that CTA can be used as the modality of choice for final diagnosis of and management decision of aortic dissection, and also to analyze CTA appearances of the aortic dissection. Methods: Aortic CTA images of 145 patients between Sept 1, 2003-Aug 31, 2005 at King Chulalongkorn Memorial Hospital (KCMH) were reviewed by two consensus radiologists. These patients’ history of management decisions and results of treatment were also reviewed. The incidence of aortic dissection and the image appearances were also analyzed. Results: The incidence of aortic dissection at KCMH was 31 cases in two years of wich 11 cases were classified as type A (35 %), while 20 cases into type B (65 %). No patient required another investigative modality after CTA diagnosis of aortic dissection. True/false lumens, intimal tear, peri-aortic fluid, pleural effusion, pericardial effusion, intramural hematoma and contrast leakage were imaging findings obtained in that order. Conclusion: CTA can replace theconventional invasive aortography and can be used as the modality of choice for management decision of aortic dissection.