Radiography Imaging Techniques

Neutral or low-density oral contrast media are a prerequisite for good-quality CT enterography [3-5] because they maximise contrast between the lumen and enhancing small bowel wall, facilitating assessment of mucosal thickening and wall stratification/enhancement patterns [1-8]. Water–methylcellulose solution, polyethylene glycol, commercially available low-density barium, 0.1% Volumen (Bracco, Milan, Italy) and milk are examples of neutral oral contrast agents with CT attenuation properties similar to that of water. Water alone usually results in inadequate distension due to rapid reabsorption, although some authors advocate its use [9]. Use of Volumen has been shown to improve the quality of bowel distension compared with water alone [4,10-12], but it remains unlicensed for use in the UK and therefore is not available. Milk was shown to give similar results as Volumen [13], but although less expensive and freely available in Europe, it may be deemed unpalatable by many patients wh...

Germ cell tumors represent 15% to 20% of all tumors of the ovary. Dermoids account for 95% of all ovarian germ cell tumors. Most of these are unilocular, contain sebaceous fluid, and are commonly referred to as mature cystic teratomas or dermoid cysts. Although these are usually asymptomatic and are incidental findings in young women, the standard treatment is surgical removal because of their potential to cause ovarian torsion or for the cyst to rupture. There is also a rare chance of malignant degeneration to squamous cell carcinoma. Although most mature cystic teratomas can be diagnosed at ultrasound, one prospective study has shown the sensitivity to be 58% with a specificity of 99%. 11  Numerous pitfalls exist in their diagnosis by ultrasound. The presence of blood clot within a hemorrhagic cyst can appear echogenic, which causes confusion in the diagnosis. Adjacent echogenic bowel can also be mistaken for a mature cystic teratoma and vice versa. MRI has a high sensitivity f...

Because relaxation times are longer at 3.0 T than at 1.5 T, there may be decreased soft-tissue contrast and decreased lesion conspicuity on unenhanced T1-weighted images (Fig 2). To compensate, longer repetition times are required to improve soft-tissue contrast when performing high-field-strength abdominal imaging. However, longer repetition times result in a longer imaging time and are often limited by the length of the patient’s breath hold. One solution that has been used for unenhanced T1-weighted imaging at higher field strengths is incorporating an inversion recovery preparatory pulse to accentuate T1 contrast. Use of a magnetization preparation prepulse for gradient-echo imaging is also beneficial (53,54). Parallel imaging techniques also may be used to decrease overall acquisition time at T1-weighted imaging.

The median nerve travels through the carpal tunnel and normally should not present variations in signal or thickness. Main findings in cases of compressive neuropathy (carpal tunnel syndrome) are thickening of the nerve proximal to the entrance of the tunnel with associated increased signal on the fluid-sensitive sequences (Figure 13). However, the findings may not be specific. More recently, diffusion tensor MRI (DTI) has been studied as a new tool for diagnosing neuropathy.25The role of MRI in carpal tunnel syndrome is to exclude a potential cause for the symptoms, such as flexor tenosynovitis, or masses/cysts within the carpal tunnel.26An incidental bifid median nerve and/or a persistent median artery should also be depicted and reported (Figure 14).27 MRI after carpal tunnel release is sometimes indicated to evaluate recurrence of symptoms. Normal postoperative findings include a complete surgical defect of the flexor retinaculum and volar extrusion of the carpal tunnel componen...

ECG gating, beta blockers, and pinpoint contrast timing bump up image quality, especially in problematic patients By: Karen Sandrick Although the heart and its vasculature dominate the center of a conventional chest CT scan, they have for the most part been ignored by radiologists. They tend to leave the diagnosis of cardiovascular disease to cardiologists skilled in viewing the beating heart on echocardiograms or evaluating nuclear medicine physiology studies. Faced with motion artifact on CT that blurs tissue edges, radiologists have lacked confidence to make definitive diagnoses of coronary artery stenosis or global cardiac disease. But as multidetector technology produces sharper images, radiologists are beginning to recognize CT's potential for generating maps of the pulmonary veins, assessing the patency of stents and coronary artery bypass grafts, ruling out pulmonary embolus, tracing collateral vessel development, and even looking at wall motion defects. Learning ...