Spectrum of scintigraphic appearance of liver hemangiomas.

Two hundred and twenty five liver hemangiomas in 166 patients were studied with Tc-99m labeled RBC and are the basis for this atlas. All hemangiomas showed various presentations of the perfusion blood pool mismatch, which is the basis for diagnosis. The size of the hemangiomas was the factor that determined the mixing of the Tc-99m RBC with the blood and, hence, the sequence of visualization of the lesion. Hemangiomas may appear as multiple lesions on liver scan and imitate metastases. Ninety-five hemangiomas appeared in 36 patients as multiple focal abnormalities. Hemangiomas are extremely variable in size. They may be huge (31 hemangiomas) and sometimes occupy most of the abdomen. Or they can be very small and are then detected only by SPECT (two cases). Thrombosed large hemangiomas appear as focal defects on Tc-99m RBC.     

Serendipity in scintigraphic gastrointestinal bleeding studies

A retrospective review of 80 scintigraphic bleeding studies performed with Tc-99m sulfur colloid or Tc-99m labeled red blood cells showed five cases where there were abnormal findings not related to bleeding. In some cases, the abnormalities were initially confused with bleeding or could obscure an area of bleeding, while in other cases, the abnormalities represented additional clinical information. These included bone marrow replacement related to tumor and radiation therapy, hyperemia related to a uterine leiomyoma and a diverticular abscess, and a dilated abdominal aorta (aneurysm). Recognition of such abnormalities should prevent an erroneous diagnosis and the additional information may be of clinical value.     

Preoperative scintigraphic evaluation of the liver and biliary tract in Caroli's disease

Caroli's disease (congenital dilatation of the intrahepatic bile ducts) is a rare condition which is usually diagnosed postoperatively. Scintigraphic evaluation of this entity is very limited. We report here a patient with Caroli's disease in whom a dichotomy in hepatic uptake of ^99mTc-HIDA (hot spots) and ^99mTc-colloid (cold spots) was observed, leading to a correct preoperative evaluation of the disease.     

Patient motion artifacts on scintigraphic gastric emptying studies

Patient motion during scintigraphic gastric emptying studies can result in the false diagnosis of gastroesophageal reflux or of accelerated gastric emptying. A simple means of detecting patient motion, by generating a time-activity curve from a region of interest drawn about a Tc-99m marker, is described.     

Pulmonary nodules causing false-positive liver scans. Preoperative and postoperative scintigraphic findings in three cases

False-positive liver scans may occur due to intrinsic hepatic anatomy, extrinsic impression on the liver from adjacent structures, or external attenuation of gamma rays. However, reports of false-positive scans due to external attenuation by pulmonary nodules are very few, and postoperative changes in liver scintigraphy have not been reported. We experienced three such cases. In each case, a pulmonary mass was located in the right posterior basal segment. The preoperative liver scan showed a focal "cold" area in the upper portion of the right lobe. This "cold" area was seen only in the posterior view, and after resection of the tumor it usually disappeared promptly unless direct liver invasion was present.     

Ultrasonic and scintigraphic imaging for malignant liver tumours in heavy drinkers

One hundred and ninetynine patients (111 with and 88 without malignant tumours) living in north east Italy, a region with a high alcohol consumption (21 litres of pure alcohol per capita), had scintigraphic and echographic liver examinations. Focal coloid defect(s) were seen in 57.6% of those with neoplasm and 47.7% of those with parenchymal non-malignant liver diseases either alone or with other changes on radioisotopic scan. Echogenic lesions on ultrasonography were confirmed in 46.2% of the livers with focal defect(s). In 80 livers histologically examined, radio-colloid imaging showed relatively good sensitivity (77%) but a bad specificity (33%) in the overall population studied and also (74% and 35% respectively) in the cancer patient group. On the contrary, echography demonstrated an excellent specificity in detecting malignancy (98%–100%) and echogenic lesions were predominantly seen in patients with neoplasm. Ultrasonography produced, however, an elevated number of false negatives primarily in cancer patients (38%). A suitable diagnostic accuracy for malignant liver tumours was achieved when scintigraphic and echographic data were simultaneously interpreted.