Usefulness of Apparent Diffusion Coefficient of Diffusion-Weighted Imaging for Differential Diagnosis of Primary Solid and Cystic Renal Masses.

BACKGROUND: To evaluate the value of diffusion-weighted imaging (DWI) for distinguishing between benign and malignant renal masses. MATERIAL/METHODS: Seventy-five patients with 75 unilateral renal lesions were included, and 75 normal contralateral kidneys served as controls. The lesions were categorized into four groups as malignant cystic, malignant solid, benign cystic and benign solid. The apparent diffusion coefficients (ADCs) were evaluated for two different b values (b=600 s/mm2 and b=1000 s/mm2). Receiving operating characteristic analysis was performed to identify threshold ADCs. RESULTS: Sensitivity and specificity were 67% and 77% (p=0.003) at the cutoff value of 1.5 for b=600 s/mm2, and 79% and 62% (p=0.004) at the cutoff value of 1.99 for b=1000 s/mm2 as regards the differentiation between solid benign and malignant renal lesions. Sensitivity and specificity were 78% and 79% (p=0.001) at the cutoff value of 3.1 for b=600 s/mm2, and 86% and 61% (p=0.003) at the cutoff value of 2.9 for b=1000 s/mm2 as regrads the differentiation between benign and malignant cystic renal lesions. CONCLUSIONS: DWI can be an effective diagnostic method for distinguishing between benign and malignant renal masses.

MRI of pneumonia in immunocompromised patients: comparison with CT.

PURPOSE: Pneumonia is an important cause of mortality and morbidity in immunocompromised patients. Computed tomography (CT) is the most sensitive imaging modality for the diagnosis and surveillance of these patients. Since CT exposes the patient to ionizing radiation, we investigated the utility of magnetic resonance imaging (MRI) in the diagnosis and surveillance of immunocompromised patients with pneumonia. METHODS: The study included 40 immunocompromised patients with pneumonia documented on CT. The patients were examined by MRI within 48 hours of CT examination. All images were obtained with three different sequences: balanced fast field echo, T1-weighted turbo spin-echo (TSE), and T2-weighted TSE. Lung abnormalities were evaluated using CT and MRI. RESULTS: Infection was determined in 36 patients (90%), while the causative organism remained unknown in four patients (10%). In all the patients, the CT findings were consistent with infection, although three patients showed no abnormal findings on MRI. CT was superior to MRI in the detection of the tree-in-bud nodules, centrilobular nodules, and halo sign (P < 0.001, for all). A significant difference was observed between the MRI sequences and CT in terms of the number of detected nodules (P < 0.001). The nodule detection rate of MRI significantly increased in proportion to the size of the nodule (P < 0.001). All MRI sequences had almost perfect agreement with CT for the detection of consolidation (к=0.950, P < 0.001), patchy increased density (к=1, P < 0.001), pleural effusion (к=0.870, P < 0.001), pericardial effusion (к=1, P < 0.001), reverse halo sign, (к=1 P < 0.001), 10-20 mm, nodules (к=0.896, P < 0.001 for CT and B-FFE; к=0.948, P < 0.001 for CT and T1- or T2-weighted imaging) 10-20 mm, >20 mm nodules (к=0.844, P < 0.001). CONCLUSION: Although CT is superior to MRI in the diagnosis of pneumonia in immunocompromised patients, MRI is an important imaging modality that can be used, particularly in the follow-up of these patients, thus decreasing to avoid ionizing radiation exposure.

Ultrasonography and contrast-enhanced CT findings of tularemia in the neck.

PURPOSE: We aimed to evaluate the ultrasonography (US) and contrast-enhanced computed tomography (CECT) findings of tularemia in the neck. METHODS: US and CECT findings of 58 patients with serologically proven tularemia were retrospectively evaluated. Forty-eight patients underwent US and 42 patients underwent CECT. Lymph node characteristics and parotid preauricular region involvement were analyzed using US and CECT. In addition, involvement of larynx, oropharynx, and retropharynx; presence of periorbital edema; and neck abscess formation were evaluated using CECT. Fine needle aspiration cytology (FNAC) results of enlarged lymph nodes were analyzed in 29 patients. RESULTS: Hypoechoic pattern, round shape, absence of hilum, and cystic necrosis were seen in most of the lymph nodes especially at level 2 and 3 on US and CECT. Matting was more commonly observed than irregular nodal border on US and CECT. Parotid preauricular region involvement was seen in 20.8% of patients on US. Oropharyngeal, retropharyngeal, laryngeal and parotid preauricular region involvement and periorbital edema were seen in 52.4%, 19.1%, 4.8%, 31%, and 9.5% of tularemia patients, respectively. Neck abscess was found in 59.5% of patients on CECT. Suppurative inflammation was the most common finding of FNAC. CONCLUSION: Tularemia should be considered in the presence of level 2 and 3 lymph nodes with cystic necrosis, matting, absence of calcification, oropharyngeal and retropharyngeal region involvement, and neck abscess, particularly in endemic areas.

An Unusual Case of Laryngeal Paraganglioma in a Patient with Carotid Body Paraganglioma: Multimodality Imaging Findings.

Multiple paragangliomas of the head and neck are rare conditions. Carotid paragangliomas are most common multiple paragangliomas. Laryngeal paragangliomas are very rare neuroendocrine tumors and usually are seen as symptomatic solitary lesions. We present multimodality imaging findings of incidentally detected laryngeal paraganglioma in a woman with synchronous carotid body paraganglioma and positive family history. To the best of our knowledge, this is the first case of laryngeal and carotid body paragangliomas in a patient with positive family history. Radiologists should keep in mind that paragangliomas may occur in various locations as multiple tumors.