Radiography Imaging Techniques

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 for t

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

Breast MRI is used as an adjunct to conventional mammographic assessment. It provides additional information in the following ways: Finding breast cancer not detected by other imaging modalities in women with increased risk. [3, 4, 5] Finding breast cancer not detected by other imaging modalities in women with dense breasts. Finding additional disease in recently diagnosed breast cancer cases (multifocal, multicentric, or bilateral disease). Finding an invasive component in ductal carcinoma in situ lesions. Breast MRI relies on detection of abnormal enhancement caused by neoangiogenesis associated with malignancy. The increasing use of breast MRI has inevitably been accompanied by increased detection of incidental enhancing abnormalities that were not detected by conventional imaging. These apparent lesions may represent normal or dysplastic tissues, cyclic hormonal changes, benign tumors, or unexpected malignant foci. The nature of such foci must be clarified so that a cancer

Greater trochanter and lesser trochanter x ray anatomy , acetabulum radiography anatomy , hip joint radiographic anatomy 

Enhanced interpretation . Mammograms can be extremely difficult for radiologists to interpret. Digital mammograms, though, are stored electronically. That means they can be analyzed by computers as well as by radiologists. Image manipulation capabilities . Film mammogram images cannot be changed. Digital mammogram images can be manipulated digitally for better clarity and visibility. For instance, the contrast of the images can be changed where necessary to provide a clearer picture. Lower average radiation dosage . Digital mammograms may take more views of each breast than film mammograms. But they use approximately 25% less radiation than film mammograms. That’s because smaller areas of the breast are imaged in each view. Easier second opinions . Since digital mammograms are stored in computers, they can easily be sent electronically to other health care professionals for analysis. Easier to store . Film mammograms produce bulky sets of films that must be stored and revisited f

There several imaging techniques that may be used to shorten the image acquisition time without shortening TR. Two techniques, fractional Nex imaging and fractional echo imaging, are presented in this section, while others will be presented in subsequent sections in this chapter. Before fractional Nex or fractional echo imaging can be understood, it is first necessary to examine a relationship between the data in different halves of  k -space. K -space data is made up of complex data representing the M x  and M y  components of magnetization. The complex data in the right half of  k -space is the complex conjugate of the data in the left half of  k -space. Similarly, the data in the top half of  k -space is the complex conjugate of the data in the bottom half of  k -space. Fractional Nex Imaging Fractional Nex imaging takes advantage of this complex conjugate relationship between the top and bottom halves of  k -space to reduce the number of phase encoding steps. In half-Nex i