False-positive hepatic blood pool scintigraphy in metastatic colon carcinoma

Hepatoblastoma Mimicking Hemangioma in Labeled Red Blood Cell Scintigraphy

Although Tc red blood cell (RBC) scintigraphy is a very specific method to differentiate a hemangioma from other hepatic masses, several cases of false-positive Tc RBC scintigraphy have been previously reported throughout the literature. We report an additional case that presented in a 15-month-old boy with hepatoblastoma showing increased labeled RBC activity mimicking hemangioma.

To what extent can diverse types of liver lesions mimic hemangiomas? A retrospective quantitative analysis of masses found to be positive in SPECT/CT with labeled blood cells - a preliminary report

Background

Although specificity of SPECT/CT examination using technetium-99m radiolabeled red blood cells (Tc-99m-RBC) for detection of liver hemangiomas is very high, it is still not perfect. It is possible to overlook a malignancy. Moreover, the difference in accumulation of RBCs between a hemangioma and uninvolved liver remains unknown.

The aim of the study is to determine the quotients of accumulation of Tc-99m-RBC in hemangiomas and in normal liver parenchyma (HEM/liv), and to verify, whether the quotient could be potentially helpful in distinguishing hemangiomas from other RBC-accumulating liver masses.

Material/Methods

34 liver lesions larger than 1.5 cm classified scintigraphically (qualitatively) in our Department as either typical or suspicious of hemangioma 1.5–4 years earlier were enrolled in this retrospective study. Their SPECT/CT images were acquired 1 hour after in vivo labeling of RBCs with Tc-99m. In reconstructed images, ellipsoidal regions of interest (ROIs) with diameters of about 1.5 cm were created in the assessed lesions (HEM) and in the uninvolved liver parenchyma (liv). The HEM/liv quotients were calculated for each mass. The results were compared with radiological data.

Results

31 lesions were found to be clinically and radiologically typical for hemangiomas, their HEM/liv ratios were at least 1.6 (smaller masses) or 1.8 (larger masses). One lesion with HEM/liv ratio equal to 1.21 was classified as metastasis. Two lesions with HEM/liv 1.42 and 1.46 were classified as benign foci other than hemangioma.

Conclusions

The quantitative analysis can be preliminarily proposed as a helpful tool in the assessment of possible liver hemangiomas.

Diffuse peritoneal metastases from primary colon cancer demonstrated by Tc-99m-labeled red blood cell scintigraphy

An 80-year-old man, who underwent complex abdominal surgery for left colon cancer 2 years earlier, was hospitalized because of severe anemia and recurrent episodes of melena. Esophagogastroduodenoscopy and colonoscopy did not reveal abnormal findings. Abdominal ultrasonographic examination and computed tomographic scan failed to detect tumor recurrence or metastatic lesions but moderate ascites was found. Tumoral marker serum levels were abnormal. Tc-99m red blood cell scintigraphy was performed and disclosed a potential site of intestinal hemorrhage: both dynamic and static images showed a slight but diffuse and persistent uptake of Tc-99m erythrocytes in the entire abdomen with no clear evidence of a site of active bleeding. These findings suggested diffuse peritoneal micrometastases, which were confirmed at autopsy.

Multiple hepatic adenomas: Tc-99m RBC liver SPECT findings with pathologic correlation

A 24-year-old man with multiple hepatic masses incidentally detected by ultrasonography underwent Tc-99m RBC liver SPECT. SPECT images showed increased blood pooling mimicking hemangiomas in two of four masses or activity similar to normal liver in the others. The patient had a 3-year history of steroid therapy for rheumatoid arthritis. Computed tomography and magnetic resonance imaging showed multiple liver lesions. Angiography revealed three hypervascular and one hypovascular mass. Microscopic examination of the enucleated specimens disclosed hepatic adenomas with many dilated sinusoids in the masses showing blood pooling and fatty change, and adenomas without dilated sinusoids in the masses not showing blood pooling. This case report shows that the appearance of hepatic adenomas can vary on Tc-99m RBC liver SPECT, depending on whether dilated sinusoid and hepatic adenomas show blood pooling. This is one of the few examples of false-positive findings that can be mistaken for hemangioma.

Pelioid-type hepatocellular carcinoma masquerading as a hepatic hemangioma on technetium-99m red blood cell scintigraphy

Technetium-99m red blood cell (RBC) scintigraphy is a very specific method to differentiate a hemangioma from other hepatic masses. The authors report a case of hepatocellular carcinoma that showed a focal area of increased uptake on Tc-99m RBC SPECT in a 60-year-old man. Dynamic computed tomography and angiography revealed features of both hemangioma and hepatocellular carcinoma. Pathologic examination showed that the portion of the hepatocellular carcinoma that showed increased uptake on Tc-99m RBC scintigraphy had peliosis, which is the likely cause of the radiotracer avidity.

Growing hepatic cavernous hemangioma demonstrated by Tc-99m red blood cell scintigraphy

Hepatic cavernous hemangiomas rarely grow. Although a few cases have been reported in the literature, none used Tc-99m red blood cell scintigraphy. The authors describe such a case here.

Technical pitfalls in image acquisition, processing, and display

Optimal image quality is an ideal in nuclear medicine that is not always realized, being subject to a variety of conditions that can act, either singly or in combination, to undermine its accomplishment. These conditions include potential defects and limitations in both the hardware and software used for the acquisition and reconstruction of nuclear medicine images. Factors relating to individual patients can contribute to these obstacles, including limitations in mobility and compliance. Importantly, suboptimal or erroneous technique is a common source of poor imaging results, with loss of diagnostic efficacy. Appropriate test selection and careful attention to patient preparation and procedural details are essential elements in avoiding image flaws and artifacts in nuclear medicine.

Scintigraphic evaluation of hepatic mass lesions: emphasis on hemangioma detection

Nuclear medicine imaging techniques continue to play a unique role in the evaluation of hepatic masses. Although many useful radiodiagnostic agents are available, the predominant nuclear medicine study used to evaluate hepatic masses in this decade is technetium-labeled red blood cell "blood-pool" scintigraphy. Hepatic blood-pool scintigraphy is extremely useful for the confirmation or exclusion of benign hepatic hemangiomas. This technique was first described in the 1970s and has vastly improved since that time. This improvement has been caused predominantly by advancements in instrumentation, especially the development of single photon emission computed tomography (SPECT) imaging. However, a perfusion/blood-pool mismatch remains unchanged as the hallmark finding for hepatic hemangiomas. The sensitivity and specificity of blood-pool scanning for the detection of hemangiomas has continued to increase over the years, and has not been equaled or surpassed by other radiographic modalities, with the possible exception of magnetic resonance imaging. Furthermore, blood-pool imaging is relatively inexpensive, simple to perform, and highly accurate. When a suspected hepatic hemangioma is confirmed by a positive radionuclide blood-pool study, the clinical evaluation of patients with hepatic masses can generally be terminated.

Nuclear imaging of solid hepatic masses

This review has focused on the unique role of radionuclide scintigraphy in characterization of hepatic mass lesions. Radionuclide scintigraphy, unlike most other imaging modalities, is based on specific physiological and biochemical properties of each pathological entity that affects the liver. Hepatic scintigraphy, with its widespread availability, noninvasive nature, and relatively low cost is a powerful adjunct to other imaging techniques in the investigation of hepatic mass lesions. We have reviewed clinical presentation and characteristic findings of most hepatic lesions and have described reported findings with all available imaging modalities with particular emphasis on hepatic scintigraphy (Table 1) as well as a suggested algorithm for workup of solid hepatic masses (Fig 6). Additionally, the role of newer, more specialized techniques including PET scanning, 123I-labeled VIP, and 111In-labeled DTPA-D-Phe-octreotide scanning are reviewed. Hepatic nuclear scintigraphy continues to play an important role in the management of patients with solid hepatic masses.

Intrahepatic, extramedullary hematopoiesis mimicking hemangioma on technetium-99m red blood cell SPECT examination

Cavernous hemangiomas are the most common lesion of the liver. Because of the risk of hemorrhage inherent in percutaneous biopsy of such lesions, noninterventional modalities (such as CT, ultrasound, MRI and Technetium-99m red blood cell imaging) have been utilized for differentiating them from other lesions. The sensitivities and specificities of these techniques vary greatly. Technetium-99m red blood cell imaging with planar and SPECT imaging has been shown to have an overall sensitivity of 89%, a specificity of 100%, and an overall accuracy of 92%. Despite its high accuracy, rare false positives have been reported with Technetium-99m red blood cell imaging with SPECT. Review of the literature indicates four cases of hepatocellular carcinoma, one case of hepatic angiosarcoma, and one case of hepatic metastases from colorectal carcinoma as having an appearance identical to hemangioma with this modality. We present an additional false positive of a focal region of intrahepatic extramedullary hematopoiesis in a patient with Gaucher's disease as having an appearance on Technetium-99m red blood cell imaging with SPECT identical to that of hemangioma.