Radionuclide Liver Spots: Indicator of Liver Disease or a Blood Flow Phenomenon

Transcription

1 Radionuclide Liver Spots: Indicator of Liver Disease or a Blood Flow Phenomenon MARC R. TETALMAN, RODNEY KUSUMI,2 GEORGE GAUGHRAN,3 AND NOBUHISA BABA4 Abnormal areas of increased uptake on liver scan have been controversial. While often said to be associated with superior vena caval obstruction, three distinctly different find- Ings are possible: hot spot, warm spot, and no spot. All of these changes can be readily explained by distinct, separate anatomic venous collateral pathways. Four cases of superior vena caval obstruction with isotopic liver flow studies are presented. Anatomy of the venous collateral system is reviewed, and the potential significance of the liver warm spot is considered. The hot spot in the liver scan has been controversial. A small number of pathologic entities has been reported to result in focal areas of increased uptake of radiocolbid on the liver scan: iatrogenic [1], abscess [2], hemangioma [3], hamartoma [4], Budd-Chiari syndrome [5-8], and hepatic venoocclusive disease [9]. A single localized area of increased activity has been most often reported secondary to superior vena caval obstruction [10-19]. This area of increased activity was felt to be secondary to the formation of collateral venous channels through the portal system of the liver. However, an additional case of a known superior vena caval obstruction with extensive collaterals did not produce any of the expected changes on liver scan [20]. The various etiologies of increased liver uptake must be characterized. Excluding such unusual occurrences as hamartoma or hemangioma, the two most common entities which produce increased localized liver uptake are superior vena caval obstruction and the Budd-Chiari syndrome. In the latter, well characterized by Meindok and Langer [6], the increased liver uptake is often confined to a hypertrophied caudate lobe, which has preserved venous drainage. This is opposed to the remainder of the liver which, due to venous occlusion, has markedly decreased peripheral uptake. Therefore, the hot spot in Budd-Chiari syndrome is an area of diffuse activity representing a lobe of the liver. In several of the previously reported cases of superior vena caval obstruction, a distinct localized area of increased uptake was seen along the inferior margin of the liver between the right and left lobes at the entrance of the portal vein. This is readily differentiated from the findings in Budd- Chiari syndrome inasmuch as the area of superior vena caval obstruction does not occupy nor represent an entire lobe of the liver. Most reports describe the hot spot on liver scans as an oddity. With the exception of two reports [15, 16], there has been little detailed attention to the abnormal anatomic venous channels which clearly explain and define the reason for the hot spot, even though animal experiments more than 40 years ago anticipated this finding [21]. We report four cases of superior vena caval obstruction with a spectrum of liver scan findings. In an attempt to explain our cases and, perhaps, some other reported cases, correlative anatomic venous collateral channel pathways are presented. We also report a liver warm spot associated with superior vena caval obstruction and explain its potential significance. The liver warm spot is an area of slightly increased uptake localized to the anterior superior aspect of the liver, away from the portal area but at the junction of the right and left lobes of the liver. It does not represent or involve a single liver lobe but, rather, a portion of two lobes of the liver at the level of the bare area. Case 1: Hot Spot Case Reports M. K., a 25-year-old female, was in good health until July 1975 when she noted a nontender right supraclavicular mass. A biopsy was interpreted as possible Hodgkin s disease. In late 1976 a chest radiograph revealed an enlarging mediastinal mass and pleural effusion. Examination of the skin revealed numerous superficial veins and varices on the anterior chest wall and the upper right abdominal area. The patient received immediate radiation therapy to the mediastinum with subsequent clearing of the right pleural effusion. Four days after the beginning of radiation therapy a liver-spleen scan showed an area of increased uptake at the inferior aspect of the liver at the junction of the right and left lobes (hot spot); the scan was otherwise normal. A flow study performed immediately afterward using 10 mci of wmtc sulfur colloid demonstrated an incomplete superior vena caval obstruction with numerous collateral channels below the diaphragm (fig. 1). Case 2: Warm Spot W. S., a 33-year-old female, was admitted for evaluation of a mediastinal mass. She was well until 2 months prior to admission when she noted hoarseness, dysphagia, and a 9 kg weight loss. A chest radiograph showed mediastinal widening. Physical findings included right axillary and supraclavicular adenopathy, a right breast mass, and a slight swelling of the face. Bilateral mammograms showed a lesion in the superior lateral quadrant of the right breast. Review of a lymph node biopsy revealed poorly differentiated metastatic adenocarcinoma of the breast. Received August 17, 1977; accepted after revision November 4, Division of Nuclear Medicine, Ohio State University Hospitals, 410 West 10th Avenue, Columbus, Ohio Address reprint requests to M. A. Tetalman. 2Department of Medicine, Ohio State University Hospitals, Columbus, Ohio Department of Anatomy, Ohio State University Hospitals, Columbus, Ohio Department of Pathology, Ohio State University Hospitals, Columbus, Ohio Am J Roentgenol , February American Roentgen Ray Society X/78/ $02.00

2 292 TETALMAN ET AL. AANT The patient developed increasing dyspnea, fever, and gross hemoptysis. Physical examination demonstrated decreased breath sounds in the left lung base, plus diffuse coarse rhonchi. There was obvious swelling of the face and arms. The lung scan was performed using 3.9 mci of viimtc MAA. The radiopharmaceutical was administered by an intravenous injection into the right antecubital fossa. The routine four-view lung scan obtained with a scintillation camera demonstrated a marked decrease in perfusion of the right lower lobe and no perfusion of the right upper and middle lobes. In addition, there was a large accumulation of activity below the diaphragm located anteriorly and somewhat to the right of the midline. A flow study, immediately obtained with 99mTc sulfur colloid (9.6 mci), demonstrated numerous collateral channels that perfused an area below the diaphragm (fig. 24). A liver-spleen scan was then performed. On the subsequent liver images, this hot spot proved to be the junction between the right and left lobes of the liver (fig. 28). The liver scan was repeated 4 days later. Initially, 1.2 mci of iflimtc sulfur colioid was injected into a vein on the dorsum of the right foot. An anterior liver image was normal at this time. A 3.5 mci dose of radiocolloid was then injected into a vein in the right antecubital fossa. A repeat anterior liver image demonstrated a warm spot superiorly at the junction of the right and left lobes (fig. 2C). The warm spot was considerably smaller and less active than on the previous scan, which included activity from both the initial lung scan and the subsequent liver scan (fig. 2D). The patient received emergency radiation therapy to the mediastinum, which continued until her death 5 days later. Fig. 1.-A, Anterior and right anterior oblique views of liver demonstrating area of increased activity (hot spot) in region of porta hepatis. B, Flow study performed after liver scan demonstrating partial superior vena caval obstruction plus collateral venous channels. Each frame represents 1 sec interval. C, Anatomic flow pattern accounting for hot spot: 1 = right brachial vein, 2 = axillary vein, 3 = subclavian vein, 4 = internal thoracic vein, 5 = superior epigastric vein, 6 = inferior epigastric vein, 7 = paraumbilical vein, 8 = left portal vein, * = partial SVC obstruction, + = umbilicus. Autopsy revealed a large metastatic undifferentiated adenocarcinoma constricting the superior vena cava. The liver contamed multiple small hepatic adenomata, the largest of which was 1 cm in diameter. There were numerous smaller adenomata each 2-5 mm in diameter located within 3 cm of the Glisson s capsule in the anterior and superior portion of the liver, at the junction of the right and left lobes. This area corresponded with the location of the warm spot on the liver scan. These adenomata were interconnected with abnormal fibrous bands. No metastatic adenocarcinoma was detected in the liver. Case 3: No Spot W. W., a 53-year-old male, was admitted for evaluation of superior vena caval occlusion; a chest radiograph showed a mass along the right mediastinum. Bilateral arm venograms demonstrated complete occlusion of the superior vena cava (fig. 4). A liver scan was performed to rule out metastatic disease. Because the patient was known to have superior vena caval obstruction, a liver flow study was performed; this demonstrated numerous collateral venous channels (figs. 3B-3D). He eventually underwent anterior mediastinal exploration which revealed a hard mass involving the lymph nodes of the superior mediastinum. Histologic examination did not reveal any evidence of carcinoma. Gram stains were positive for organisms which appeared to be Histoplasma capsulatum. Case 4: No Spot J. G., a 42-year-old male with known metastatic carcinoma of the lung with secondary superior vena caval obstruction,

3 RADIONUCLIDE LIVER SPOTS 293 C INJ. R.FOOT INJ. R. ARM Fig. 2. -A, Flow study after lung scan demonstrating abnormal venous collateral channels entering activity below diaphragm. Note lung activity on left plus flow totally bypassing heart. Each frame represents 1 sec interval. B, Liver scan obtained after flow study localizing abnormal activity in liver. C, Initial liver image (left) obtained by injection of 99mc sulfur colloid into a vein in dorsum of right foot. Subsequent liver image obtained by injection into right antecubital fossa. Note warm spot (arrow) at junction of right and left lobes in region of base area of liver. D, Anatomic flow pattern accounting for warm spot: 1 = right brachial vein, 2 = axillary vein, 3 = subclavian vein, 4 = internal thoracic vein, 5 = superior phrenic vein, 6 = inferior phrenic vein, 7 = hepatic and cava veins, 8 = bare area of the liver, * = complete superior vena caval obstruction. was admitted with symptoms of an acute abdomen. On the day prior to this admission he noticed a slightly decreased urinary output and the insidious onset of lower abdominal crampy pain. Physical examination demonstrated puffy eyelids and a supple neck with gross jugular venous distention. Abdominal examination revealed bulging flanks. The liver percussed to 11 cm and was not tender. There was swelling of both upper extremities. The patient also had venous collateral channels visible on his thorax and abdomen. Liver scan was included in the evaluation for disseminated metastatic disease; it was negative (fig. 4A). A subsequent liver flow study demonstrated numerous collateral channels, all which bypassed the liver (figs. 48 and 4C). The patient s hospital course was marked by ANT LIVER LAO LIVER ANT SPLEEN improvement in all respects. The precise etiology of the acute renal failure was never determined. Discussion Several possible explanations have been proposed for the etiology of the hot spot on liver scan. One possibility is a tumor which actively accumulates sulfur colloid. This possibility was excluded by autopsy examination of the liver in case 2. A more likely explanation is that the increased abnormal blood flow localized to a specific area of the liver presents the surrounding reticuloendothelial cells with a greater portion of colloid to be

4 294 TETALMAN ET AL. A Fig. 3.-A, Bilateral arm yenograms demonstrating complete superior vena caval obstruction with numerous collateral channels. B, Combined cardiac hepatic flow study (1 sec per frame) demonstrating complete superior vena caval obstruction with no flow through liver. C, Anterior liver scan obtained after flow study. No abnormality seen. 0, Anatomic flow pattern: 1 = left brachial vein, 2 = axillary vein, 3 = subclavian vein, 4 = superior intercostal vein, 5 = accessory hemiazygos vein, 6 = hemiazygos vein, 7 = ascending lumbar vein, * = complete superior vena caval obstruction. phagocytized compared to the remainder of the reticuloendothelial cells of the liver. The warm spot is probably related to the venous collateral channels in the area of the localized collections of various sized adenomata and interstitial fibrosis. These additional intrinsic liver abnormalities may have resulted in a fairly large area of venous stasis between the left and right lobes of the liver allowing prolonged phagocytosis of the sulfur colloid. This large diffuse area of stasis resulted in the warm spot rather than a concentration of colloid over a smaller area (hot spot). Cases 3 and 4 had clearly demonstrated long-standing superior vena caval obstruction. In these cases, as in previously reported ones, the liver scans were typically normal since the abnormal collateral venous channels were separate from the the hepatic venous circulation. This can be demonstrated either by an isotopic or arteriographic flow study. Therefore, formation of liver spots follows well defined anatomic and physiologic principles. Three potential findings may be associated with a superior vena caval obstruction, only one of which may have any prognostic significance. 1. A superior vena caval obstruction may not be associated with any focal change on the liver scan. Usually there is no spot. 2. The hot spot is simply a well localized abnormal blood flow phenomenon of collateral channels unrelated to any intrinsic liver disease. It is characteristically located on the anterior inferior aspect of the liver, near the portal area, at the junction of the right and left lobes. 3. The warm spot may be caused by any large area of

5 RADIONUCLIDE LIVER SPOTS 295 AANT RAO venous stasis. It is located on the anterior superior aspect of the liver, away from the portal area, at the junction of the right and left lobes. The warm spot cannot apparently differentiate between benign or malignant disease of the liver, but it may suggest intrinsic liver pathology when it is the only obvious abnormality present. REFERENCES 1. Helbig H: Focal iatrogenic increased radiocolloid uptake on Iiverscan.J NucI Med 14: , Chayes Z, Koenigsberg M, Freeman L: The hot hepatic abscess. J NucI Med 1 5 : , Volpe J, Johnston G: Hot hepatic hemangioma: a unique radiocolloid-concentrating liver scan lesion. J Surg Oncol 2: , Pasquier J, Dorta T: Hyperfixation of radiocolloid by the liver.jnuclmed 15:725, Tavill A, Wood E, Kreel L, Jones E, Gregory M, Sherlock 5: Liver physiology and disease. Gastroenterology 68 : , Meindok H, Langer B: Liver scan in Budd-Chiari syndrome. J NucI Med 1 7 : , Chaudhuri T, Chaudhuri T, Suzuki Y, Christie J: Liver scan in the Budd-Chiari syndrome. JAMA 221 : , 1972 Fig. 4.-A, Negative liver scan. B, Flow study after liver scan (1 sec per frame) demonstrating numerous collateral venous channels bypassing heart and liver. C, Anatomic flow pattern: 1 = left brachial vein, 2 = axillary vein, 3 = lateral thoracic vein, 4 = thoracoepigastric vein, 5 = superficial epigastric vein, 6 = femoral vein, 7 = great saphenous vein, - = complete superior vena caval obstruction. 8. Carulli N, Boraldi F, Roncaia R, Paigaia A: Liver scans in the Budd-Chiari syndrome. JAMA 223 : 1 161, Haneline L, Uszler J, Sommer D: Liver scan hot spot in hepatic veno-occlusive disease. Radiology : , Coel M, Halpern 5, Alazraki N, Ashburn W, Leopold G: lntrahepatic lesion presenting as an area of increased radiocolloid uptake on a liver scan. J NucI Med 13: , Mikolajkow A, Jasinski W: Increased focal uptake of radiocolloid bythe liver.jnuclmed 14:175, Joyner J: Abnormal liver scan (radiocolloid hot spot ) associated with superior vena caval obstruction. J NucI Med 13: , Morita E, McCormack K, Weisberg A: Further information of a hot spot in the liver.j NucI Med 14: , Hughes F: The value of hepatic scintiangiography and static liver scans in superior vena caval obstruction: case report. J NucI Med 1 6 : , Holmquest D, Burdine A: Caval-portal shunting as a cause of focal increase in radiocolloid uptake in normal livers. J NucI Med 1 4 : , Lee KR, Preston D, Martin N, Robinson A: Angiographic documentation of systemic-portal venous shunting as a cause of a liver scan hot spot in superior vena caval obstruction. Am J Roentgenol 1 27 : , 1976

6 296 TETALMAN ET AL. 17. Hopkins G: Superior vena caval obstruction and increased radiocolloid activity on liver scintiphotos. J NucI Med 14:883, Gooneratne N, Buse M, Quinn J, Selby J: Hot spot on hepatic scintigraphy and radionuclide venacavography. Am JRoentgenol 129: , Yeh 5, Gargia A, Benua A: Abnormal radiocolloid and MAA uptake by the liver in superior vena caval obstruction. Clin Nucl Med 2: , Hattner A, Shames D: Nonspecificity of the radiocolloid hepatic hotspot for superior vena caval obstruction. J NucI Med 15: , Carlson H: Obstruction of the superior vena cava. Arch Surg 29: , 1934