Computed tomography of the thyroid gland.

Many imaging modalities are used in the investigation of the thyroid gland. In this multitude of methods, none of the applied modalities per se is able to discriminate between the benign or malignant nature of a thyroid lesion with absolute certitude. In this thesis, CT-imaging in various conditions of the thyroid gland is described. At the same time, the advantages and the risks of the application of free iodine as selective contrast agent for thyroid imaging in selective cases is studied. In chapter II a review of imaging modalities is described. A survey is given of the value of each imaging modality for the daily routine practice. In chapter III, relevant technical aspects of CT scanning with respect to the thyroid investigation are highlighted. These include technical possibilities typical for CT-scanning, dosimetric aspects and the patient preparation protocol. The CT-scan procedure is described for the neck region and the mediastinum. Chapter IV summarizes some important aspects of the iodine metabolism of which the radiologist should be aware. Chapter V describes the advantages of our scanning method in different patient groups. Evidence is obtained that CT-investigation of patients with a MEN 2-syndrome in the early assessment of tumor localization is of value. Application of CT in patients with a scintigraphically demonstrated cold nodule is shown to have consequences. Refinement of this diagnosis is possible and of additional value. The appearance of a multinodular goiter on CT is shown to be characteristic. Typical CT-features of this lesion are described which makes a strong indication in the direction of the histological diagnosis possible. With respect to the mediastinal masses of unknown origin, CT-signs of these lesions are considered. CT-examination can differentiate between goiters, benign cysts, infiltrative lesions and enlarged lymph nodes. Some attention is paid to future technical developments of CT, i.e., dual energy scanning. Early experiences are promising, especially in the field of thyroid imaging.

The heterogeneity of distal arthrogryposis.

A study of distal arthrogryposis is described including neurology, electromyography, cerebral and muscular CT-scanning, and muscle and nerve biopsies. In four cases presenting with congenital distal contractures, various neuromuscular disorders were diagnosed. They were respectively, congenital myopathy with core-like structures, congenital hypertrophic neuropathy, axonal neuropathy and anterior horn cell disease. The role of cerebral disorders in the pathogenesis of distal contractures is also considered. The significance of abnormal dermatoglyphics in the determination of the prenatal time of onset of congenital myopathies and arthrogryposis is discussed. Our findings provide evidence for the hypothesis that distal arthrogryposis may not be a distinct clinical entity with an autosomal dominant inheritance pattern, but a symptom, indicating various cerebral, neuromuscular and connective tissue disorders, present in numerous congenital syndromes with different modes of inheritance. In addition the value of electromyography, nerve conduction velocity studies, muscle and cerebral CT-scanning, and histology of muscle and nerve biopsies in the differential diagnosis of (distal) arthrogryposis is stressed.

A case of asymmetrical arthrogryposis--a clinical study and a preliminary report on the value of CT-scanning.

Following the introduction of the conception that arthrogryposis is a symptom and not a clinical entity, a case of the very rare asymmetric form of neurogenic arthrogryposis is presented. The asymmetry of congenital contractures and weakness is associated with hemihypotrophy. The value of muscular CT-scanning prior to muscle biopsy is demonstrated. Muscular CT-scanning shows the extension of adipose tissue, which has replaced damaged muscles and thereby indicates the exact site for muscle biopsy. Since orthopaedic treatment in arthrogryposis can be unrewarding due to severe muscular degeneration, preoperative scanning may provide additional important information on muscular function and thus be of benefit for surgery. The advantage of muscular CT-scanning in other forms of arthrogryposis requires further determination. The differential diagnosis with Werdnig-Hoffmann disease is discussed.