Imaging in Cushing's syndrome.

Once the diagnosis of Cushing's syndrome (CS) has been established, the main step is to differentiate between ACTH dependent and independent disease. In adults, 80% of CS is due to ACTH-dependent causes and 20% due to adrenal causes. ACTH-secreting neoplasms cause ACTH-dependent CS. These are usually anterior pituitary microadenomas, which result in the classic Cushing's disease. Non-pituitary ectopic sources of ACTH, such as a small-cell lung carcinoma or carcinoid tumours, are the source of the remainder of ACTH-dependent disease. In the majority of patients presenting with clinical and biochemical evidence of CS, modern non-invasive imaging can accurately and efficiently provide the cause and the nature of the underlying pathology. Imaging is essential for determining the source of ACTH in ectopic ACTH production, locating the pituitary tumours and distinguishing adrenal adenomas, carcinomas and hyperplasias. In our chapter we review the adrenal appearances in ACTH-dependent and ACTH-independent CS. We also include a discussion on the use of MRI and CT for the detection and management of pituitary ACTH secreting adenomas. CT of the chest, abdomen and pelvis with intravenous injection of contrast medium is the most sensitive imaging modality for the identification of the ectopic ACTH source and detecting adrenal pathology. MRI is used for characterising adrenal adenomas, problem solving in difficult cases and for detecting ACTH-secreting pituitary adenomas

The role of CT in predicting the surgical feasibility of exenteration in recurrent carcinoma of the cervix

In women with recurrent cervical cancer, there is a 52% 5-year survival rate when exenteration of the centrally placed tumor is performed. If not exenterated, the 2-year survival rate is less than 2%. The purpose of this study is to ascertain whether CT can predict inoperability reliably leading to a reduction in operations which do not have a curative outcome. The records of patients with recurrence of cervical cancer who underwent laparotomies for exenteration over the last 10 years under the care of one surgeon were reviewed. The CT scans were retrospectively assessed by two radiologists without knowledge of the subsequent outcome of the laparotomy. CT scans on 31 patients were reviewed, 21 of whom underwent a radical surgical procedure. Using CT criteria, 9 cases were felt to be operable with a curative intent and the remaining 22 cases were deemed to be inoperable. The sensitivity of CT prediction of inoperability is 93% (95%Cl:66-100%) and the specificity is 47% (95%Cl:23-72%). In three cases ascites was the only abnormal finding other than the central pelvic mass and in all of these cases a radical procedure with clear resection margins was possible. When the group with ascites alone was not considered to have peritoneal disease underlying the ascites, the sensitivity of CT prediction of inoperability is 93% (95%Cl:66-100%) and the specificity of 65% (95% Cl:38-86%). If, in addition, lymphadenopathy is not taken as definite evidence of inoperability, the specificity rises to 82% (95%Cl:57-96%). A high quality CT scan is highly specific for predicting inoperability based on extension of the tumor to the pelvic side walls, encasement of adjacent vessels or ureteric dilatation and so should be a major tool in assessing women for radical surgical treatment of recurrent cervical cancer. If ascites is the only abnormal finding other than the central pelvic mass then exploration should be undertaken.link_to_subscribed_fulltex

Insulinomas may present with normoglycemia after prolonged fasting but glucose-stimulated hypoglycemia.

BACKGROUND: Insulinomas are rare but are the most common cause of hyperinsulinemic hypoglycemia in the adult population. Diagnosis of this pathology relies on clinical features along with laboratory tests and imaging investigations to aid in localization. One of the most robust standard tests used for establishing a biochemical diagnosis is the prolonged (72 h) fast. Currently, it is recommended that a prolonged supervised fast be performed, at least for 48 h if not for 72 h, and many would take the absence of hypoglycemia after a 72-h fast as evidence excluding the diagnosis. METHODS: We employed prolonged fasts and standard glucose tolerance tests, plus imaging studies and surgical pathology, in two patients with suspected insulinomas. RESULTS: The prolonged 72-h fast was normal in both the patients, whereas in both cases a prolonged oral glucose tolerance test clearly demonstrated the induction of severe hyperinsulinemia followed by significant hypoglycemia. Surgical removal confirmed the presence of insulinomas in each case. CONCLUSIONS: Although the sensitivity of the 72-h fast is high and still plays an important role in the diagnosis of an insulinoma, we suggest that a "normal" test result should be interpreted in the light of clinical symptoms