Correlative imaging of the liver and hepatobiliary system

Bile Collection Detected With BrIDA Scintigraphy in a Patient With Hepatocellular Carcinoma

A 47-year-old man, with a history of anabolic steroid abuse, developed hepatic adenomatosis and multifocal hepatocellular carcinoma. He underwent ultrasound and CT follow-up, showing multiple solid and fluid hepatic lesions. Consequently, hospitalization was required because of high fever (up to 39°C), weakness, and anorexia. An abdominal CT scan revealed an enlargement of one of the intrahepatic fluid collections. Biochemical and microbiological analyses of a fluid sample showed bilirubin and bile acids as well as Streptococcus cristatus and Enterobacter cloacae. Thus, the patient underwent Tc-trimethylbromo-iminodiacetic acid scintigraphy, demonstrating bile collection in the lesion with a flow from a bile duct.

Focal nodular hyperplasia--a review of myths and truths

BACKGROUND

Focal nodular hyperplasia (FNH) is a benign hyperplastic lesion of the liver with no known malignant potential. It has generated much interest due to the frequency with which it presents with atypical features on radiological imaging. Often resulting in misdiagnosis. Moreover, the understanding of particular subtypes of this lesion at a molecular level has changed in recent years. This may have implications on how certain subtypes should be managed.

PURPOSE

This review aims to analyse current literature pertaining to FNH and to provide clinically relevant advice regarding diagnosis and management.

The burden of incidental findings in clinical practice in a tertiary care center

BACKGROUND

To evaluate the prevalence and clinical burden of serendipitously discovered abnormalities in hospitalized patients, unrelated to their presenting symptoms and physical signs.

METHODS

A total of 478 patients consecutively admitted in the Department of Medicine were enrolled in the study. In the end of first diagnostic work-up, the previously undetected imaging or endoscopic asymptomatic abnormalities termed as incidental findings (IFs) were recorded and some of them were further investigated.

RESULTS

One hundred thirty eight (28.8%) patients had IFs. The most common IFs were located in the kidney and genitourinary system followed by liver and gallbladder. The most common method of detection of IFs was ultrasonography (US) of the abdomen. The patients with IFs compared with those without, were older (P=0.007), had no previous hospitalizations (P<0.001) and stayed longer in the hospital (P<0.001). The 25 (18.1%) patients with IFs were not evaluated further. One hundred seventy seven IFs discovered in 113 patients were further evaluated by medical specialists and additional tests were performed if warranted. In the end of the diagnostic work-up, in a total of 113 patients with IFs, 78.7% had insignificant and 21.2% potentially significant IFs. The latter group had higher rate of IFs compared with the former group, usually more than 3 (P=0.017).

CONCLUSIONS

IFs were prevalent in a hospital population. Hospitalized patients with IFs were more than 60 years old and had no previous hospitalization. A large number of IFs were potentially significant deserving further clinical management.

An assessment of the accuracy of hepatic and splenic size based upon a clinician's physical examination, a radiologist's impression and the actual liver and spleen volumes calculated by CT scanning

OBJECTIVES

In this study, a radiologist's impression of liver and spleen size based on computed tomography (CT) images, calculated liver and spleen volumes as determined radiologically, and findings of a hepatologist were compared.

METHODS

One hundred and ninety-four consecutive subjects seen by a hepatologist were evaluated clinically and radiologically. Liver and spleen volumes were calculated based on CT images and compared to radiologist's impression and to expected liver volume based on body weight. Covariate analysis was used to determine the relationships between different variables, and a value of P < 0.05 was considered to be significant.

RESULTS

Liver volume calculated on the basis of CT scans correlated to liver size based on the hepatologist's clinical exam but not to the radiologist's impression of liver size. In contrast, spleen volume based on CT scans, splenic size based upon radiologist's impression, and clinician's assessment all correlated well.

CONCLUSIONS

A variety of biases determine and/or affect the radiologist's assessment of liver size but not of splenic size.

Contrast-enhanced ultrasonographic spoke-wheel sign in hepatic focal nodular hyperplasia

BACKGROUND

To determine the utility of contrast-enhanced ultrasonography (CEUS) in assessing hepatic tumors with central feeding arteries found by color/power Doppler ultrasonograophy (CDUS/PDUS).

METHODS

We prospectively studied 37 hepatic tumors (34 patients), with a mean size of 2.9cm and each having a central feeding artery, by CDUS/PDUS. The CEUS was performed with a galactose-based microbubble contrast agent. The detection of a spoke-wheel sign was interpreted as evidence of focal nodular hyperplasia (FNH). All patients underwent tumor biopsies or surgical resection.

RESULTS

CEUS showed a central feeding artery with a spoke-wheel sign in 36 tumors, including 34 FNHs and 2 hepatocellular carcinomas. The remaining tumor was demonstrated to be FNH despite the absence of a spoke-wheel sign as detected by CEUS. The sensitivity of the spoke-wheel sign or central scar for FNH was 97.1% (34/35), 40% (14/35), 28.6% (10/35), 50% (8/16) and 0% (0/15) for CEUS, CDUS/PDUS, dynamic computed tomography (CT) or magnetic resonance imaging (MRI), hepatic angiography and liver scintigraphy, respectively. The two hepatocellular carcinomas showed scirrhous changes histologically.

CONCLUSIONS

CEUS is more sensitive than CDUS/PDUS, dynamic CT, MRI, hepatic angiography and liver scintigraphy in the detection of the spoke-wheel sign or central scar in FNH. Scirrhous hepatocellular carcinoma should be included in the differential diagnosis for liver tumors with spoke-wheel sign detected by CEUS.

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.

Positron emission tomography scanning in the evaluation of hepatocellular carcinoma

BACKGROUND/AIMS

18F-fluorodeoxyglucose uptake allows estimation of glucose metabolism by tumor cells using positron emission tomography (PET). We evaluated the role of PET imaging in the diagnosis of hepatocellular carcinoma.

METHODS

PET images were collected after intravenous injection of 8-12 mCi of 18F-FDG in 20 patients with hepatocellular carcinoma (HCC). PET tumor activity level was assessed on a scale of 1 to 4 compared to normal liver tissue. The PET score was compared with abdominal computerized tomography (CT) scan results and between tumors of different grades and differentiation.

RESULTS

Of the 20 patients studied, 11 (55%) had positive PET scans (PET score: 3 or 4) while nine (45%) were negative (PET score: 1 or 2). CT scan was positive in 18 patients (90%) and negative in two (10%). PET, however, revealed metastases in three patients that were not seen on CT. On pathological review, well-differentiated and low-grade tumors had lower PET scores. Comparison of the well-differentiated with the moderately- and poorly-differentiated tumors revealed a statistically significant difference. No statistical significance was observed between the moderately- and poorly-differentiated tumors or between different tumor grades and PET scores.

CONCLUSIONS

The sensitivity of PET in diagnosis of HCC was 55% compared to 90% for CT scanning, although only PET detected some tumors (including distant metastases). Well-differentiated and low tumor grades had lower activity on PET and correspondingly lower PET scores. PET imaging may help assess tumor differentiation and may be useful in the diagnosis and staging and prognostication of HCC as an adjunct to CT.

Characterization of hepatic adenoma with atypical appearance on CT and MRI by radionuclide imaging

The appearance of hepatic adenomas on CT and MRI are highly variable because of their varied histopathology, and images of adenomas are at times indistinguishable from those of other hepatic tumors. The authors present two patients with hepatic adenomas with extremely atypical CT and MRI manifestations demonstrating a "nodule-in-nodule" appearance. Radionuclide imaging in both patients showed decreased Ga-67 uptake in the adenomas compared to normal liver, negative colloid (Tc-99m phytate) uptake in the adenomas, and early uptake and subsequent retention of Tc-99m PMT. This correctly characterized the unique histopathologic features of the resected tumors. Radionuclide imaging using a combination of radiotracers may play an important role in aiding the diagnosis of this rare benign tumor, despite variable CT and MRI appearances.

Evaluation of the solid hepatic mass

With the expanding use of abdominal imaging studies, evaluation of solid hepatic masses has become a common clinical challenge. In this review, the clinicopathologic characteristics of the most common causes of solid hepatic masses have been discussed. As the case scenarios demonstrate, the appropriate selection of imaging techniques and proper management of an individual patient depend on the clinical context. Often, complementary radiologic studies are necessary to narrow the differential diagnosis. Percutaneous biopsy or surgery is frequently required to confirm the diagnosis and to exclude malignancy definitively. The evaluation and management of solid hepatic masses is a cooperative venture that requires a multidisciplinary approach.

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.