Unenhanced CT Scans Research Articles

Calcified renal stones and cyst calcifications in autosomal dominant polycystic kidney disease: clinical and CT study in 84 patients.

Although renal calculi and cyst calcifications occur commonly in patients with autosomal dominant polycystic kidney disease (ADPKD), their true frequency is unknown because it is difficult to distinguish between the two with excretory urography and sonography. A detailed analysis of renal calcifications in ADPKD based on CT findings has not been performed. Accordingly, we retrospectively evaluated clinical and CT findings in 84 patients with ADPKD to determine the frequency of calculi and cyst calcifications, the relationship of these abnormalities to symptoms, and possible factors in their pathogenesis. Of the 84 patients, 53 had both IV contrast-enhanced and unenhanced CT scans and 31 had unenhanced scans only. We examined unenhanced CT scans of all 84 patients for renal calcifications. However, we classified renal calcifications into stones and cyst calcifications in only the 53 patients, because it is often difficult to distinguish between the two when only unenhanced scans are available. Of 84 patients, 18 (21%) had passed renal calculi or had stones treated surgically and 42 (50%) had renal calcifications on CT. Of the 53 patients who had both enhanced and unenhanced CT scans, 19 (36%) had renal calculi on CT. Patients with stones had significantly higher frequencies of previous flank pain (68% vs 35%) and of urinary tract infections (63% vs 18%) than did those without calculi. Cyst calcifications occurred in 13 (25%) of 53 patients and were probably a consequence of cyst hemorrhage. Cyst calcifications were found significantly more often in older patients with larger kidneys and worse renal function. We conclude that renal stones have a high rate of occurrence among patients with ADPKD and are a significant cause of morbidity in this disorder. Cyst calcification is also common in patients with ADPKD, particularly those with more advanced cystic disease.

Epithelioid hemangioendothelioma of the liver: imaging findings with pathologic correlation.

Hepatic epithelioid hemangioendothelioma is a rare malignant neoplasm that has nonspecific clinical signs and symptoms and can be difficult to diagnose on the basis of biopsy results. Radiologists may suggest the diagnosis of this slowly progressive neoplasm by recognizing its characteristic radiologic features. We correlated images from CT (13), sonography (nine), and MR (six) with pathologic findings in resected whole livers (eight) and biopsy specimens (five) from 13 patients 25-58 years old. Gross pathologic examination showed a repetitive pattern of multiple solid tumor nodules, in a predominantly peripheral distribution, with coalescence as individual nodules exceeded 4 cm. Tumor nodules had a hyperemic rim. Lesions adjacent to the capsule often produced capsular retraction. These findings correlated well with imaging findings. On CT, the lesions were of low attenuation, peripherally based, and with capsular retraction or flattening in nine (69%) of 13 patients. Unenhanced CT scans showed superior conspicuity over contrast-enhanced CT scans (9/13, 69%) and showed the extent of lesions more accurately in all cases (13/13, 100%). In nine patients, lesions had a peripheral enhancement pattern of alternating attenuation values correlating with the hyperemic rim at pathologic evaluation. On sonograms, the tumors were solid and predominantly hypoechoic. On MR, tumor signal was low on T1-weighted and high on T2-weighted images, with a low-signal halo present around many of the lesions. CT, sonographic, or MR findings of coalescent peripheral hepatic masses with capsular retraction are highly suggestive of hepatic epithelioid hemangioendothelioma.

Localized fat collection adjacent to the intrahepatic portion of the inferior vena cava: a normal variant on CT.

We describe a normal focal collection of fat that has the appearance of a mass on CT scans. The fat is adjacent to the intrahepatic portion of the inferior vena cava and is contiguous to the fat around the subdiaphragmatic portion of the esophagus. This finding occurred in 11 (0.5%) of 2227 patients who had CT scans at our institution. The fat collections did not change in size or shape on follow-up CT scans obtained 2 to 29 months later (mean, 14 months). The localized fat collections were at the level of or above the confluence of the hepatic veins and the inferior vena cava, and were medial to the inferior vena cava. They were less than 22 mm in length, oval, and had attenuation values ranging from -113 H to -23 H on unenhanced CT scans. The collections enhanced slightly on scans obtained after contrast administration. T1-weighted (600/15) MR images obtained in three cases showed a high-intensity mass that was contiguous to high-intensity fat around the esophagus, medial to the intrahepatic portion of the inferior vena cava. Our experience suggests that a masslike fat collection adjacent to the intrahepatic portion of the inferior vena cava is a normal variant on CT scans and should not be mistaken for an abnormality.

Candidal splenic abscesses.

Candidal splenic abscesses.F S Chew, P L Smith and D BarboriakAudio Available | Share

Calcification of the ligamentum arteriosum in children: a normal finding on CT.

Calcification of the ligamentum arteriosum is a rare finding on plain radiographs. We commonly have seen the calcification on unenhanced CT scans of the chest, a finding not previously reported. A retrospective review of unenhanced CT scans of the chest was undertaken to determine the frequency of the described finding. Seven (13%) of 53 patients had a well-demarcated focus of calcification in the region of the ligamentum arteriosum. None of these patients had evidence of a patent ductus arteriosum. Calcification within the ligamentum arteriosum was seen in 13% of routine CT examinations of the chest in children and should not be confused with a pathologic process producing mediastinal calcifications.

High-attenuation mediastinal masses on unenhanced CT.

On unenhanced CT scans, a variety of mediastinal masses contain areas with attenuation values higher than the attenuation value of the chest wall musculature. The increased attenuation may be diffuse or focal and may be a result of calcium deposition, high iodine content, or areas of acute hemorrhage. This report illustrates the gamut of high-attenuation mediastinal masses seen on unenhanced CT. Masses that are of high attenuation only on IV contrast-enhanced images (e.g., aberrant vessels) are not included.

CT of hilar cholangiocarcinoma: late contrast enhancement in six patients.

Hilar cholangiocarcinoma usually appears on CT scans as a low-density or isodense mass that abruptly obstructs converging dilated bile ducts. In four of six patients with histopathologically proved hilar cholangiocarcinoma who had late enhanced CT 8-15 min after dynamic CT, the lesion was seen as a high-density mass instead of the low-density lesion seen earlier on unenhanced and dynamic CT scans. The other two patients had ring enhancement with evidence of a thickened wall of the bile duct both on early and late enhanced CT scans. In the first four patients, carcinoma invaded the neighboring hepatic parenchyma and produced a mass, whereas in the last two, carcinoma was localized in the wall of the bile duct. Histopathologically, all lesions consisted of adenocarcinoma associated with a dense fibrotic tissue. As late enhanced CT shows hilar cholangiocarcinoma as a high-density mass, the exact location of the tumor and its relation to neighboring vessels can be determined, especially in relatively small tumors, and differentiation from sclerosing cholangitis is possible.

Pigmented villonodular synovitis of the knee: computed tomographic appearances

Five patients with pigmented villonodular synovitis (PVNS) of the knee demonstrate the value of preoperative, contrast medium-enhanced CT scanning. The technique is shown to be particularly useful in locating recurrent lesions and in demonstrating that popliteal and posterior calf masses are due to PVNS affecting the knee joint itself. In two of the five patients PVNS was not considered a possibility before the CT scan, and none had evidence of bone erosion on plain radiographs. In none of the patients was the unenhanced CT scan able to demonstrate evidence of decreased radiolucency due to fat within the tumour or density greater than the adjacent skeletal muscle, indicating haemosiderin deposits.

CT evaluation of suspected hepatic metastases: comparison of techniques for i.v. contrast enhancement

Although IV injection of contrast material is widely used for detection and follow-up of hepatic metastases on CT, the optimal method of contrast enhancement has not yet been defined. A prospective study was performed in 50 consecutive patients with suspected hepatic metastases. Lesion size and detectability were compared on unenhanced CT scans, scans obtained during a bolus injection of contrast material (early bolus phase), and scans obtained during a rapid infusion after the loading bolus. A total of 60 hepatic lesions were evaluated in 26 patients, 19 with histologic confirmation of metastases and seven with strong supportive evidence. The bolus phase allowed detection of 15% more lesions than did examination during the rapid-infusion phase. Lesion size varied, depending on the timing and method of contrast administration; the largest measurements were obtained during bolus injection of contrast material. In addition, bolus administration of contrast material subjectively resulted in the best lesion detection. Because the three techniques of IV contrast enhancement may produce different size measurements, sequential examinations must be tailored appropriately. Scanning during the bolus phase is technically possible with current CT equipment and is recommended as the primary CT screening examination for hepatic metastases.

Radiographic characteristics of benign liver tumors: Focal nodular hyperplasia and hepatic adenoma

The imaging characteristics of focal nodular hyperplasia are varied. Unenhanced computed tomography reveals the attenuation of these lesions, in general, to be slightly less than that of normal liver; after contrast enhancement, their attenuation is equal to (isodense) or greater than (hyperdense) that of normal liver. This, of course, depends on the rate at which the contrast material is injected and the timing of scans after its injection. Central scar, a helpful finding when present, was not noted as a common finding at the time of computed tomography or ultrasound examination. Ultrasound examinations, in general, showed these lesions to be homogeneous, isoechoic or hypoechoic tumors. The angiographic findings revealed them, in general to be more vascular than the normal liver with an intense, homogeneous capillary stain. Hypovascular focal nodular hyperplasia does occur, but rarely. The blood supply to these tumors was most commonly from peripheral vessels, in contrast to previous reports of a central blood supply being more common. The technetium-99m sulfur colloid liver-spleen scan is often the key to the diagnosis of focal nodular hyperplasia. The majority of these tumors at the time of liver-spleen scanning will be seen as areas of normal or increased uptake; this is a reliable clue to the diagnosis of focal nodular hyperplasia. lf the radionuclide scan is not diagnostic, however, the combined findings of CT, ultrasound and angiography often are. Hepatic adenomas also clearly have a varied imaging presentation. The angiographic findings show these tumors to be hypervascular with small areas of hypovascularity within them. Blood is supplied to the adenomas by peripheral vessels in most cases, and there is no intense capillary stain. Computed tomography shows hepatic adenomas, in general, to be hypodense in the absence of contrast enhancement. Yet on contrast enhanced scans, they are complex lesions with multiple ranges of attenuation located within them. Acute hemorrhage can be seen in approximately half the unenhanced CT scans. By sonography, hepatic adenomas, in general, display intrinsic areas that are isoechoic, hyperechoic, and hypoechoic; and they are invariably nonhomogeneous lesions. These tumors appear as focal defects in all cases on technetium-99m sulfur colloid liver-spleen scans.

High-density renal cysts in autosomal dominant polycystic kidney disease demonstrated by CT.

Unenhanced abdominal CT scans of 35 patients with autosomal dominant polycystic kidney disease (ADPKD) showed multiple high-density (58-84 HU) renal cysts in 42.9% of patients, occasional high-density cysts in 25.7%, and no high-density cysts in 31.4%. These high-density cysts were usually subcapsular and were more frequent in patients with markedly enlarged kidneys and flank pain at the time of CT. Several were found to contain altered blood on pathological analysis. Follow-up CT often showed a reduction in cyst densities, although some cysts developed mural calcification and calcification of their contents. High-density cysts are probably produced by cyst hemorrhage. This may occur randomly as part of the natural history of the disease or may result from minor trauma to the enlarged kidneys. Renal carcinomas occur rarely in ADPKD and may occasionally be hyperdense. However, high-density cysts may usually be distinguished from carcinomas on CT by their smooth contours, sharp interfaces with renal parenchyma, homogeneity, and lack of contrast enhancement.

ASYMPTOMATIC CONGENITAL CMV: CT AND ABR ABNORMALITIES

Five infants with asymptomatic congenital CMV documented by urine culture in the first week of life were evaluated in a prospective study of the relationship between maternal CMV serology during pregnancy and neurodevelopmental outcome of the infant. Initial assessment at 1 week to 3 months of age consisted of unenhanced cranial CT scan, ABR, and neurologic exam, with reassessment at 6-9 months of age. Three of the 5 infants had abnormalities on one or more of these exams. Two infants had abnormal lucency of the cerebral white matter on CT scan; on subsequent scans, one had mildly dilated lateral ventricles and one had no abnormalities. Both infants were mildly hypotonic and had abnormal ABR's characterized by prolonged Wave V latencies and Wave I-V intervals (≥2 S.D. above mean for age, Salamy and McKean, Electro Clin Neuro, 1976), with Wave I latency. Serial ABR's revealed gradual decrease in latency times to limits by 6-9 months of age. A third infant had both an abnormal CT scan (abnormally prominent interhemispheric fissure and cisternal spaces), but ABR. In the absence of other perinatal risk factors, three normal infants had CT, ABR and/or neurologic abnormalities which may be related to the in utero CMV infection. However, the pathophysiology and long term significance of these findings are not clear. Longitudinal assessment will be essential to define the full impact of in utero exposure to CMV.

Recurrence, with intracranial extension, of an intraorbital hydatid cyst: A clinical follow-up case report

An intraorbital hydatid cyst, removed in 1965 via a transfrontal craniotomy ruptured during its initial operative isolation and gave clinical signs of recurrence. Exophthalmos and amblyopia progressed to amaurosis, about 13 years after surgery. The recurrence was documented with an unenhanced CT scan, showing a large retrobulbar mass extending posteriorly into the left middle cranial fossa.

Use of CT Scans in an Out‐patient Headache Population: An Evaluation

SYNOPSISA total of 177 consecutive patients with either tension or migraine headaches were examined with unenhanced CT Scans. For the overall group 28% were abnormal while 26% of the patients with migraine and 33% of those with tension headaches had abnormal scans. Our findings were similar to several smaller studies in more seriously disabled patients. Follow‐up studies are planned to determine if our CT Scan results are indicative of a progressive disorder.