Structural and functional imaging in parkinsonian syndromes.

Movement disorders with parkinsonian features are common, and in recent years imaging has assumed a greater role in diagnosis and management. Thus, it is important that radiologists become familiar with the most common imaging patterns of parkinsonism, especially given the significant clinical overlap and diagnostic difficulty associated with these disorders. The authors review the most common magnetic resonance (MR) and molecular imaging patterns of idiopathic Parkinson disease and atypical parkinsonian syndromes. They also discuss the interpretation of clinically available molecular imaging studies, including assessment of cerebral metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET), cortical amyloid deposition with carbon 11 ((11)C) Pittsburgh compound B and fluorine 18 ((18)F) florbetapir PET, and dopaminergic activity with iodine 123 ((123)I) ioflupane single photon emission computed tomography (SPECT). Although no single imaging test is diagnostic, a combination of tests may help narrow the differential diagnosis. Findings at (123)I ioflupane SPECT can confirm the loss of dopaminergic neurons in patients with parkinsonism and help distinguish these syndromes from treatable conditions, including essential tremor and drug-induced parkinsonism. FDG PET uptake can demonstrate patterns of neuronal dysfunction that are specific to a particular parkinsonian syndrome. Although MR imaging findings are typically nonspecific in parkinsonian syndromes, classic patterns of T2 signal change can be seen in multiple system atrophy and progressive supranuclear palsy. Finally, positive amyloid-binding PET findings can support the diagnosis of dementia with Lewy bodies. Combined with a thorough clinical evaluation, multimodality imaging information can afford accurate diagnosis, allow selection of appropriate therapy, and provide important prognostic information.

Malignant involvement of the peripheral nervous system in patients with cancer: multimodality imaging and pathologic correlation.

The clinical and imaging evaluation of peripheral neuropathies in patients with cancer is challenging. It is critically important to differentiate malignant invasion of the peripheral nervous system from nonmalignant causes, such as radiation-induced neuritis, neuropathy associated with chemotherapy, and inflammatory neuropathies. Contrast material-enhanced magnetic resonance (MR) imaging is the initial noninvasive test of choice; however, interpretation can be challenging when the anatomic features are distorted by prior surgery, radiation, or both. Fluorine 18 ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is an imaging adjunct to MR imaging that is particularly helpful for evaluating peripheral nerves because the metabolic activity depicted with (18)F-FDG PET/CT helps differentiate malignant from benign disease and assists in making certain management decisions. For example, sites of high (18)F-FDG activity in a peripheral nerve can be targeted to increase the diagnostic yield of a biopsy because malignant involvement of peripheral nerves can be patchy. Of note, (18)F-FDG PET/CT can show clinically unsuspected metastases elsewhere in the body. If cancer is found, (18)F-FDG PET/CT allows excellent assessment of treatment response. (18)F-FDG PET/CT is also useful in evaluating primary nerve sheath tumors in that such tumors with low metabolic activity on FDG PET/CT images are unlikely to be malignant, although the specificity is limited. It is essential to have a good understanding of the imaging characteristics of benign and malignant causes of peripheral neuropathy if (18)F-FDG PET/CT is to be used effectively for accurate diagnosis.

The "Michelangelo Code": The Quest for Universal Truth.

Michelangelo's unparalleled frescoes in the Sistine Chapel have been traditionally construed to represent the traditional, Roman Catholic interpretation of the Seven Days of Creation in the Book of Genesis and the Last Judgement. Indeed, in September 2018, Pope Francis I offered a benediction for the Vatican's art treasures and for "those who contributed to the Church's history through art." A number of studies have suggested that Michelangelo concealed anatomic information about the human brain in his renderings of God and biblical prophets and saints. Was the anatomic content of these images purposeful or coincidental? Was the anatomy intentionally concealed? Is there a common pattern with symbolic connotations in the anatomic representations? Was Michelangelo sending an encoded message? In this study, we analyze the imagery in the Sistine frescoes in light of the literature surrounding Michelangelo's artistry with a particular interest in the relationship between the certain purported anatomic depictions and details demonstrable using scientific and anatomic techniques available during the High Renaissance.

Septation of the anorectal and genitourinary tracts in the human embryo: crucial role of the catenoidal shape of the urorectal sulcus.

BACKGROUND: Previous studies of the tracheoesophageal sulcus and the sulci of the developing heart have suggested that the catenoidal or saddle-shaped configuration of the sulcus had mechanical properties that were important to developmental processes by causing regional growth limitation. We examined the development of the human perineal region to determine if a similar configuration exists in relation to the urorectal septum. We wished to re-examine the controversial issue of the role of the urorectal sulcus in the partitioning of the cloaca. METHODS: Digitally scanned photomicrographs of serial histologic sections of embryos from Carnegie stages 13, 15, 18, and 22, obtained from the Carnegie Embryological Collection were used. Each image was digitally stacked, aligned, and isolated using image-editing software. Images were compiled using 3-D image-visualization software (T-Vox), into full 3-D voxel-based volume renderings. Similarly, digital models were made of the urogenital sinus, anorectum, cloaca, allantois, mesonephric ducts, ureters, and kidneys by isolating their associated epithelium in each histologic section and compiling the data in T-Vox. Methods were developed to create registration models for determining the exact position and orientation of outlined structures within the embryos. RESULTS: Models were oriented and resectioned to determine the configuration of the urorectal sulcus. The results show that the urorectal sulcus maintains a catenoidal configuration during the developmental period studied and, thus, would be expected to limit caudal growth of the urorectal septum. CONCLUSION: The observations support the concept that the urorectal septum is a passive structure that does not actively divide the cloaca into urogenital and anorectal components.