questions_Radiology

Educational objective: Emphasize usefulness of contrast radiography in diagnosis of intussusception.

Endoscopy is superior to contrast radiography in that it provides direct visualization, an ability to biopsy, and it delivers therapeutic interventions. Endoscopy is 90% sensitive and almost 100% specific compared to contrast radiography with 50% sensitivity and 90% specificity. Therefore, answers A, B, C, and E benefit from clearer identification, therapy or biopsy ability. Intussusception of the small bowel and its intestinal obstruction are not reached by conventional endoscopies. Large bowel intussusception is usually associated with a mucosal lesion such as a neoplasm. However, manipulation prior to surgery and endoscopy in the presence of bowel obstruction are relative contraindications to endoscopy.

Educational objective: Review the features of different imaging methods for imaging area of thyroid gland and lower neck.

Thyroid ultrasonography is particularly useful for measuring the size of the gland or individual nodules, and for evaluation of the effects of therapy. Also, it is useful to differentiate between solid and cystic lesions. However, this technique is limited to thyroid tissue in the neck, and cannot be used for substernal lesions. Nuclear medicine scans of the thyroid may give a rough estimate of the size and nodularity but no finer details can be elicited. Chest x-ray may be able to detect some substernal lesions, but certainly is not the method of choice for this purpose. MRI provides an excellent image of the thyroid gland, including posterior or substernal extension of goiter (or malignancy). MRI is invaluable for the demonstration of tracheal compression from a large goiter, tracheal invasion or local extension of a thyroid malignancy or metastases to local or mediastinal lymph nodes.

This patient most likely has pancreatic insulinoma. All of his symptoms are consistent with recurrent episodes of hypoglycemia. The hallmark of insulinoma (pancreatic â-cell tumors) is symptomatic hypoglycemia caused by unregulated insulin secretion. These tumors are the second most common functioning tumors of the islet cells (gastrinomas are most common). Patients are usually in the 5th to 7th decade of life. Whipple’s triad (classic presentation of insulinoma) consists of fasting hypoglycemia, symptoms of hypoglycemia, and prompt relief of symptoms following intravenous injection of glucose. Weight gain may occur due to increased food intake to counteract the symptoms of hypoglycemia. Symptoms of hypoglycemia include slurred speech, visual disturbances, psychological alterations, confusion, headache, and ultimately coma and death. Secondary release of catecholamines causes pallor, palpitations, diaphoresis, cardiac arrhythmias, and tremulousness. In the early course, symptoms are intermittent (due to episodic release of insulin). Since those tumors are highly symptomatic, they are usually discovered while still small (multiple tumors are found in about 10% of cases), and those are malignant in about 10% of cases. These tumors are seen also as a part of multiple-endocrine-neoplasia-syndrome type I. Diagnosis is made by demonstrating hypoglycemia and an inadequate response of insulin to the hypoglycemia (by fasting under close supervision most patients develop hypoglycemia within 24 hours – test may take 72 hours). Diagnosis depends on demonstration of inadequate insulin suppression with low blood glucose levels. In addition, rising cortisol level should be demonstrated to exclude hypothalamic-pituitary-adrenal insufficiency. Exogenous administration of insulin and sulfonylurea also has to be excluded as well as severe liver failure and tumors that secrete insulin like growth factors.

In this case the tumor is demonstrated as a highly vascular lesion on digital subtraction arteriography of the pancreas, but it is now much more common to use CT scanning (50% sensitive), endoscopic ultrasonography (80-90% sensitive), and angiography with selective venous sampling (80% sensitive) to detect those tumors.

The condition demonstrated in this picture is polycystic kidney disease (despite the name, the cysts may also be seen in the liver, pancreas and spleen). In overt disease (like this one) diagnosis is easy since enlarged kidneys containing multiple cysts are easily demonstrated by ultrasonography or CT-scanning. Hepatic cysts are seen in about one-half of patients (usually females over age 40). Other extrarenal manifestations of polycystic kidney disease include colonic diverticula, umbilical and inguinal hernia, cardiac valve diseases (25-30% of cases – mitral valve prolapse and aortic regurgitation are most common) and cerebral aneurysms (4-10% of patients - leading to subarachnoidal hemorrhage).

The condition depicted is chronic subdural hematoma. Lesion is visible in right frontoparietal region as a crescent of the diminished density. Acute subdural hematoma would present as a similar crescent but density of the fluid would be higher (blood) than in this case (cells disintegrated and debris mostly resorbed). Epidural hematoma presents as a collection of blood that usually has a convex inner surface (toward the brain) because of the higher pressure under which the blood is entering the epidural space. Also epidural hematomas are usually limited to one cranial bone since the dura is tightly attached to the areas of cranial sutures.

Normal pressure hydrocephalus is manifested on CT-scanning as big dilated lateral ventricles with no asymmetry and no other pathology. Localization and shape of the lesion make a diagnosis of brain tumor highly unlikely.

Herpetic encephalitis is characterized by lesions in the temporal and parietal lobes of the brain and clearly affects the brain, not the pericerebral structures.

The classification of pulmonary involvement in sarcoidosis is based upon the radiographic stage of disease:

o Stage I – Bilateral hilar adenopathy and often associated right paratracheal adenopathy. It is seen is about 50% of patients as initial presentation of pulmonary sarcoidosis.
o Stage II – Bilateral hilar adenopathy and interstitial infiltrates which are usually more prominent in the upper lung zones. These findings are present at initial diagnosis in 25% of patients.
o Stage III – Interstitial disease with shrinking hilar nodes.
o Stage IV – Advanced fibrosis.

The radiograph in question exhibits marked interstitial pulmonary infiltrates and hilar and paratracheal adenopathy. This makes his radiographic finding fit into the stage II. There is no stage V.

It is immediately clear that the right hemithorax is smaller than the left. This is caused by the loss of volume on the right side as evidenced by a much steeper descent of the ribs on the right side. The whole mediastinum is pulled somewhat to the right (trachea is not in the middle). The region of the right lower lobe is opacified signifying that volume loss occurred in this area. Around the densely opacified area there is also an area of patchy infiltrates indicating that the area is not just atelectatic.

Finally, although some pleural effusion might be present in this patient it is not the sole finding. Pleural effusions have no tendency to cause shrinking of the hemithorax space on the same side.

Most of the bone metastases stimulate bone remodeling in the site of the malignant cell mass and as a result cause increased accumulation of bone-seeking radiopharmaceuticals. This is used to detect bone metastases in a wide variety of malignant neoplastic diseases. However, some more indolent lesions may result in lesions that are invisible on bone scanning or even producing destruction of bone without any remodeling (cold lesions). These lesions also may be poorly visible on bone scan. The diseases most commonly producing those invisible bone metastases are multiple myeloma and thyroid cancers. In patients with these diseases, a bone scan should not be used to survey the skeletal system for metastatic disease.

This patient suffered subcutaneous emphysema that was caused by traumatic attempts to place an endotracheal tube. This is evidenced by the very prominent outlines of the muscle bundles of the pectoralis muscle. Pneumomediastinum may be present in this patient but it is impossible to see it on this x-ray.

There are no signs of significant pleural effusion in this patient, and this is not a complication that is seen during intubation attempts. However, there is a density seen on the left lateral pleural area which most likely represents a postoperative collection of loculated fluid.

There are no signs of pneumothorax in this chest x-ray, and there are no signs of hemidiaphragm paralysis. Patient does have cardiomegaly and a permanent pacemaker placed in the right pectoral area with electrodes visible in the right heart.

Educational objective: Review different imaging methods for identification of renal calculi.

Tests used for confirmation of diagnosis include plain abdominal film, renal ultrasonography, intravenous pyelography and CT scanning.

Abdominal plain film identifies most radio opaque stones (calcium, struvite and cystine) but will miss radiolucent ones (urate) or small stones (especially if they overlay bony structures).

Intravenous pyelography is used in most cases and is relatively safe, despite use of the contrast. However, CT scanning may soon replace it as first used imaging modality.

Ultrasonography is the method of choice for patients who want to avoid radiation exposure. It has about equal sensitivity and specificity as plain abdominal film (64 and 100%). Machines with

Doppler capabilities improve sensitivity, but are cumbersome for patients and are heavily operator dependent. CT scanning has become a gold standard in recent years and is able equally well to distinguish radiolucent and opaque stones.

Histologically, the majority of gallbladder cancers are adenocarcinomas. Among the adenocarcinomas, the mucinous adenocarcinoma is relatively uncommon. Porcelain gallbladder is a rare finding and the risk of gallbladder cancer is significantly increased in this population. Although plain abdominal radiographs have been a standard technique for demonstrating right upper quadrant calcification, sonograms and CT scans appear to be more sensitive. In some patients, plain abdominal radiographs may show no abnormalities. It is no longer considered adequate to use only plain radiographs when evaluating possible calcifications in the upper abdomen