Usefulness of per-rectal portal scintigraphy with technetium-99m pertechnetate for prognosis of primary biliary cirrhosis

BACKGROUND/AIMS: Conventional methods predicting survival in patients with primary biliary cirrhosis are based on the results of blood tests and on clinical condition, both of which may be affected by treatment. Portal circulation can be evaluated in a relatively noninvasive manner by per-rectal portal scintigraphy. We used this method to evaluate portal hemodynamics and assess prognosis in patients with primary biliary cirrhosis. METHODOLOGY: Per-rectal portal scintigraphy with Tc-99m pertechnetate was done in 51 patients with primary biliary cirrhosis. A solution containing Tc-99m pertechnetate was instilled into the rectum, and serial scintigrams were taken while radioactivity curves for the liver and heart were recorded sequentially. The per-rectal portal shunt index was calculated from the curves. RESULTS: The shunt index was higher in patients with stage IV primary biliary cirrhosis than in those with stage I, II, or III primary biliary cirrhosis. On the basis of portal shunt index, the patients were divided into those with a shunt index of less than 18%, and those with a shunt index of 18% or more. The cumulative survival rate was lower among patients with the higher shunt index. On regression analysis, the portal shunt index was found to be significantly related to survival. CONCLUSIONS: Our results indicate that per-rectal portal scintigraphy with Tc-99m pertechnetate can be used to non-invasively evaluate the portal circulation of patients with primary biliary cirrhosis and is useful in establishing prognosis in such patients.     

Primary biliary cirrhosis complicated by severe hypoxemia

The case reported here is of a 61-year-old woman diagnosed with hepatopulmonary syndrome. She had had severe hypoxemia for 5 years. In room air, her arterial oxygen tension was low, and although we anticipated that treatment with oxygen would increase it, the treatment failed to do so. Pulmonary perfusion imaging with Tc-99m-labelled macroaggregated albumin showed an arterio-venous shunt in the lungs. Blood tests and liver scanning with Tc-99m-labelled galactosyl human serum albumin showed abnormalities of liver function, and per-rectal portal scintigraphy with Tc-99m pertechnetate showed severe portal hypertension. Inspection of a biopsy specimen taken under ultrasonographic guidance showed primary biliary cirrhosis of Scheuer stage I. The causes of hepatopulmonary syndrome are unknown, but seem to include a decrease in hepatic functional reserve, portal hypertension, or other factors. The development of hepatopulmonary syndrome due to portal hypertension in this patient is of interest.     

Natural course of portal hemodynamics in patients with chronic liver diseases, evaluated by per-rectal portal scintigraphy with Tc-99m pertechnetate

Portal circulation can be evaluated in a relatively noninvasive way by per-rectal portal scintigraphy. We used this method to evaluate portal hemodynamics in patients with chronic liver diseases and underlying hepatic viral infection; the patients did not need sur-gery or sclerotherapy, or refused it, so changes in the natural course were identified. A solution of Tc-99m pertechnetate was instilled into the rectum, and serial scintigrams were taken while radioactivity curves for the liver and heart were produced. The per-rectal portal shunt index was calculated from the curves. In a longitudinal study, 70 patients (9 with mild chronic hepatitis, 10 with moderate chronic hepatitis, 7 with severe chronic hepatitis, 22 with cirrhosis but without varices, and 22 with both cirrhosis and varices) were examined at least twice at intervals of 12–102 months (mean, 39 months). The shunt index was higher for more severe disorders, increasing in the order of mild chronic hepatitis, moderate chronic hepatitis, severe chronic hepatitis, cirrhosis without varices, and cirrhosis with varices. The mean annual changes in the mean shunt index were 1.0% in mild chronic hepatitis, 4.4% in moderate chronic hepatitis, 6.1% in severe chronic hepatitis, 10.7% in cirrhosis without varices, and 6.2% in cirrhosis and varices. Cirrhotic patients were arbitrarily divided into two groups of roughly equal size on the basis of the shunt index at the first examination. In those with a shunt index of 30% or more, the mean annual change was 4.7%. The patients with a shunt index of less than 30% had a mean annual change of 11.8%. Changes in the portal hemodynamics were not steady. The shunt index rose gradually as disease advanced from mild to moderate and to severe chronic hepatitis and cirrhosis of the liver, after which the index rose rapidly when varices developed, slowing later. (Received Aug. 18, 1997; accepted Dec. 19, 1997)     

Analysis of hepatic hemodynamics by a new method of per-rectal portal scintigraphy using 99mTcO4- (direct intramural administration of radioisotope)

To depict of porto-systemic collaterals clearly, and to analyze of hemodynamics of liver, we developed new method of per-rectal portal scintigraphy (direct intramural administration of 99mTcO4- by 23G needle). And we used this method in patient with liver diseases (acute hepatitis: 5, chronic hepatitis: 7, liver cirrhosis: 25 cases). From time activity curve of the liver and the heart, liver/heart ratio; index of porto-systemic shunt via inferior mesenteric vein (IMV) and first flow ratio(k); index of portal blood flow from IMV pathway/index of hepatic total blood flow were calculated. In our method, the images of portal vein, liver, heart, especially porto-systemic collaterals were visualized more clearly than enema methods. The liver/heart ratio was significantly lower in patients with liver cirrhosis than that in non-cirrhotic patients (p less than 0.01), which indicated that patients with liver cirrhosis had more porto-systemic collaterals than non-cirrhotic diseases. The k was more lower in liver cirrhosis than in acute hepatitis (p less than 0.01). And the k was also more lower in chronic hepatitis than in acute hepatitis (p less than 0.1), which indicated that portal blood flow via IMV reduced in early stage of chronic liver diseases. In conclusion, new method of per-rectal portal scintigraphy has more advantage for analysis of hepatic hemodynamics than enema methods.     

Evaluation of the formation of esophageal varices by per-rectal portal scintigraphy

Portal circulation in patients with liver diseases was evaluated by 99mTc-pertechnetate per-rectal portal scintigraphy, and we retrospectively examined the relationship between the extent of abnormality in the portal circulation and the development of esophageal varices. The per-rectal portal shunt index (PRPSI) was calculated for 13 healthy subjects and 79 patients with chronic hepatitis and 214 with cirrhosis of the liver. In the healthy subjects, the mean PRPSI was 4.8%. In the patients with hepatitis, the mean PRPSI was 8.4%, and in the patients with cirrhosis, it was 48.5%. The PRPSI was significantly higher in the cirrhotic patients with esophageal varices than in the without, and also in the cirrhotic patients with encephalopathy than in those without. The cumulative incidence of esophageal varices in the 3 years of the study in patients whose PRPSI was 20% or over was significantly higher than that in patients whose PRPSI was under 20%. The results suggested that this non-invasive method should be useful for predictions of the formation of esophageal varices.     

Prediction of esophageal varices in cirrhosis by per-rectal portal scintigraphy

Portal circulation in patients with chronic liver disease was evaluated by per-rectal portal scintigraphy, and per-rectal portal shunt indices were calculated to estimate the extent of the portosystemic shunt. The purpose was to identify patients with cirrhosis at special risk of developing esophageal varices. The cumulative incidence of varices in 3 years of the study in patients whose shunt index was originally 20% or over, was significantly higher than that in patients whose shunt index was originally under 20%. The cumulative survival rate in 7 years of the study in patients whose shunt index was originally under 70% was significantly higher than that in patients whose shunt index was originally 70% or over. The information obtained by calculating the shunt index could be used by physicians in out-patient clinics when deciding the schedule with which to monitor patients using barium esophagogram or endoscopy, and choosing the examination method.     

Per-rectal portal scintigraphy with technetium-99m pertechnetate for the early diagnosis of cirrhosis in patients with chronic hepatitis.

We evaluated the role of per-rectal portal scintigraphy with 99m-technetium pertechnetate (99m-Tc test) for early diagnosis of cirrhosis. Forty patients with biochemical evidence of chronic liver disease were studied. Laparobiopsy documented chronic active hepatitis (CAH) without cirrhosis in 22 of the patients and CAH with cirrhosis (CAHc) in 18 patients. Clinical or laboratory findings could not differentiate between CAH and CAHc. Twelve healthy volunteers served as controls. The results, expressed as shunt index (SI), i.e., the ratio between heart radioactivity and the sum of heart and liver radioactivity in the first 30 s of observation, were: controls 5.66 +/- 1.66, CAH 15.27 +/- 2.83 and CAHc 24.88 +/- 3.95. A significant difference between the mean SI values in the three groups studied (F = 142.71, p less than 0.0001) was observed. At values less than 17, our test showed a predictivity of 100% for cirrhosis exclusion, while at values higher than 19 the predictive positive value for a diagnosis of cirrhosis was 100%. Invasive diagnostic procedures should be performed only in patients with SI values between 17-19.     

Per rectal portal scintigraphy as a useful tool for predicting esophageal variceal bleeding in cirrhotic patients

AIM： To investigate potential roles of per rectal portal scintigraphy in diagnosis of esophageal varices and predicting the risk of bleeding. METHODS： Fifteen normal subjects and fifty cirrhotic patients with endoscopically confirmed esophageal varices were included. Patients were categorized into bleeder and non-bleeder groups according to history of variceal bleeding. All had completed per rectal portal scintigraphy using ^99mTechnetium pertechnetate. The shunt index was calculated from the ratio of ^99mTechnetium pertechnetate in the heart and the liver. Data were analyzed using Student＇s t-test and receiver operating characteristics. RESULTS： Cirrhotic patients showed a higher shunt index than normal subjects （63.80 ± 25.21 vs 13.54 ± 6.46, P 〈 0.01）. Patients with variceal bleeding showed a higher shunt index than those without bleeding （78.45 ± 9.40 vs 49.35 ± 27.72, P 〈 0.01）. A shunt index of over 20% indicated the presence of varices and that of over 60% indicated the risk of variceal bleeding. CONCLUSION： In cirrhotic patients, per rectal portal scintigraphy is a clinically useful test for identifying esophageal varices and risk of variceal bleeding.     

Relationship between endotoxin antibody levels and portal systemic shunt evaluated by per-rectal portal scintigraphy

Abstract The reasons for the high frequency of endotoxaemia in cirrhosis, whether poor liver function or abnormal portal circulation, are not known. Accurate measurement of endotoxin itself is difficult. Instead, in this study an enzyme-linked immunosorbent assay was used to measure levels of IgA, IgG and IgM antibodies to endotoxin in patients with chronic liver disease and underlying hepatic viral infection. The relationships between the results and clinical symptoms or the presence of a portal systemic shunt were investigated. The median level of IgA antibodies was not different in patients with chronic hepatitis and those with cirrhosis, and the same was found for IgM, but the median level of IgG antibodies was significantly higher in the patients with cirrhosis. When patients with cirrhosis were grouped by the presence or absence of ascites or hepatocellular carcinoma, no significant difference was observed in any of these antibody levels. However, in cirrhotic patients with varices, the level of IgG antibodies to endotoxin was significantly higher than in patients without varices. For evaluation of the portal systemic shunt, the per-rectal portal shunt index was calculated. There was a significant correlation ( R = 0.431, P < 0.001) between the per-rectal portal shunt index and the level of IgG antibodies to endotoxin. That is, the degree of abnormality in the portal haemodynamics was correlated with the level of IgG antibodies to endotoxin in patients with liver disease.     

经皮脾门静脉核素显像、B超及胃镜对肝硬化门脉高压诊断价值的对比研究

为探讨经脾门静脉核素显像、胃镜及B超检查在肝硬化门脉高压诊断中的价值及其相关性,采用99m锝-植酸钠（99mTc-Phytate）经脾细针穿刺给药法对58例肝病与非肝病患者进行了经脾门静脉单光子发射计算机断层（SPECT）显像,以观察及门脉循环情况,计算门体分流指数（PSSI）,并与胃镜、B超进行比较。结果显示,经脾门静脉核素显像可将肝硬化门脉高压分为四型,即无分流型、有分流型（包括肝内、外分流）、有侧支循环型、完全肝外分流型。PSSI值非肝病对照组为0.192±0.068,慢性肝病组为0.246±0.057,肝硬化门脉高压组为0.541±0.082。按肝硬化ChildA、B、C分级,三组分别为0.384±0.052、0.523±0.072、0.680±0.081。若以PSSI＞0.36为判别阈,肝硬化组总阳性率为91.7％,其诊断价值明显优于B超及胃镜。提示经脾门静脉核素显像既能显示脾门静脉形态及侧支循环,又能测定PSSI,有助于肝硬化的早期诊断、治疗选择及预后判断。     

Estimation of portosystemic shunt by transrectally administered 123I-IMP

Portosystemic shunt index was estimated in 7 patients without liver disease and 95 patients with various liver diseases by portal scintigraphy with transrectally administered 123I-iodoamphetamine (IMP). The shunt index was 0% in patients without liver diseases, 5.3% in acute hepatitis, 5.9% in chronic inactive hepatitis, 11.4% in chronic active hepatitis, 56.6% in compensated liver cirrhosis and 88.1% in decompensated liver cirrhosis. The shunt index was significantly higher in liver cirrhosis, especially decompensated stage. In 5 of 9 patients with acute hepatitis, shunt index was 0%. In 3 of remaining 4 patients with elevated shunt index, shunt index became 0% within 1-2 months. Significant relationship was observed between the shunt index and hepatic function tests such as ChE, albumin, gamma-globulin and ICG-R15. These results suggest that the shunt index is independent of hepatic cell necrosis and reveals the shunted blood flow exactly. Therefore, this technique is useful for evaluating the portosystemic shunt in various liver diseases.     

Type C chronic hepatitis associated with thrombocytopenia in two patients

Abstract Portal hypertension in the presence of chronic hepatitis is generally thought to develop during the progression of the chronic hepatitis to cirrhosis. Before the establishment of assays for diagnosing hepatitis C virus infection, such a case of portal hypertension without liver cirrhosis could be misdiagnosed as idiopathic portal hypertension. It had not fully determined whether portal hypertension might precede the onset of cirrhosis in type C chronic hepatitis. This report presents two cases of women with chronic hepatitis C who developed severe thrombocytopenia; each showed splenomegaly and hypersplenism due to portal hypertension. Angiographic study and histological analysis were conducted to determine the cause of the portal hypertension. Histological evaluation showed an intrahepatic presinusoidal block pattern and fibrotic changes in the periportal area, but no evidence of liver cirrhosis or of other incidental complications such as idiopathic portal hypertension. Both of these patients exhibited normal platelet counts after splenectomy. Thus, type C chronic hepatitis can lead to portal hypertension, as demonstrated in these two patients.     

Staging of portal hypertension and portosystemic shunts using dynamic nuclear medicine investigations

AIM： To explore portal hypertension and portosystemic shunts and to stage chronic liver disease （CLD） based on the pathophysiology of portal hemodynamics. METHODS： Per-rectal portal scintigraphy （PRPS） was performed on 312 patients with CLD and liver angioscintigraphy （LAS） on 231 of them. The control group included 25 healthy subjects. We developed a new model of PRPS interpretation by introducing two new parameters, the liver transit time （LTT） and the circu-lation time between right heart and liver （RHLT）. LTT for each lobe was used to evaluate the early portal hypertension. RHLT is useful in cirrhosis to detect liver areas missing portal inflow. We calculated the classical per-rectal portal shunt index （PRSI） at PRPS and the hepatic perfusion index （HPI） at LAS. RESULTS： The normal LTT value was 24 ± 1 s. Abnormal LTT had PPV = 100% for CLD. Twenty-seven noncirrhotic patients had LTT increased up to 35 s （median 27 s）. RHLT （42 ± 1 s） was not related to liver disease. Cirrhosis could be excluded in all patients with PRSI 〈 5% （P 〈 0.01）. PRSI 〉 30% had PPV = 100% for cirrhosis. Based on PRPS and LAS we propose the classification of CLD in 5 hemodynamic stages. Stage 0 is normal （LTT = 24 s, PRSI 〈 5%）. In stage 1, LTT is increased, while PRSI remains normal. In stage 2, LTT is decreased between 16 s and 23 s, whereas PRSI is increased between 5% and 10%. In stage 3, PRSI is increased to 10%-30%, and LTT becomes undetectable by PRPS due to the portosystemic shunts. Stage 4 includes the patients with PRSI 〉 30%. RHLT and HPI were used to subtype stage 4. In our study stage 0 had NPV = 100% for CLD, stage 1 had PPV = 100% for non-cirrhotic CLD, stages 2 and 3 represented the transition from chronic hepatitis to cirrhosis, stage 4 had PPV = 100% for cirrhosis. CONCLUSION： LTT allows the detection of early portal hypertension and of opening of transhepatic shunts. PRSI is useful in CLD with extrahepatic portosystemic shunts. Our hemodynamic model stag     

Technetium-99 m sestamibi imaging in patients with subacute thyroiditis

To determine if subacute thyroiditis (SAT) is associated with changes in the regional perfusion of the thyroid gland, we performed Tc-99 m sestamibi scans on eleven patients with SAT who had painful goiter and clinical thyrotoxicosis. Eleven patients had Tc-99 m pertechnetate and Tc-99 m sestamibi scintigraphy during the acute stage of SAT. The thyroid uptake ratio of sestamibi was compared with the laboratory data and color Doppler ultrasonography. Tc-99 m pertechnetate scintigraphy in the thyroid was markedly reduced during the acute stage of SAT. Conversely, Tc-99 m sestamibi showed diffuse increased uptake in the thyroid region, suggesting increased perfusion. On the other hand, there was near absence of vascularization in the acute phase and slight increase in the recovery phase by color Doppler ultrasonography. The clearance rate of Tc-99 m sestamibi during the early phase (from 10 min to 1 h) was decreased in the acute stage of SAT. The sestamibi uptake ratio correlated with serum immunosuppressive acidic protein (IAP) in the acute stage of SAT and the sestamibi uptake ratio in the recovery stage of SAT was correlated with serum thyrotropin levels. Tc-99 m sestamibi uptake in the early phase in the acute stage of SAT may reflect the inflammatory process associated with SAT.     

Differences in Portal Hemodynamics in Cirrhosis and Idiopathic Portal Hypertension

A comparative study of portal hemodynamics was made in 79 cirrhotics (24 cirrhotics with a large spleen greater than or equal to 500 cm3 in volume, 55 cirrhotics with a spleen less than 500 cm3 in volume), 22 patients with idiopathic portal hypertension, and 63 healthy adults who served as the control for portal and splenic venous flows. Portal and splenic venous flows were significantly increased in the group order of the cirrhosis without splenomegaly group, the cirrhosis with splenomegaly group, and idiopathic portal hypertension group. Intrahepatic shunt index was significantly greater in the cirrhosis with splenomegaly group than in the cirrhosis without splenomegaly group, and it was negligible in the idiopathic portal hypertension group. Portal vein pressure was significantly elevated in the cirrhosis with splenomegaly group than in the cirrhosis without splenomegaly and idiopathic portal hypertension groups. Postsinusoidal resistances were significantly greater in the two groups of cirrhosis than in the idiopathic portal hypertension group, whereas presinusoidal resistance was significantly greater in the idiopathic portal hypertension group than in the two groups with cirrhosis. It is concluded that these differences are inconsistent with the view that cirrhosis with splenomegaly comes from idiopathic portal hypertension.     

Portal circulation in monkeys and humans studied after ingestion of a capsule containing a radionuclide

Capsules (8 x 30 mm) of technetium-99m pertechnetate were designed for measurement of portal blood flow. Most of the radionuclide entered the superior mesenteric vein. The capsule was taken orally and monitored with a collimator for scintigraphy until it reached the small intestine, when a magnetic field completed an electrical circuit in a sensor, burning a thread, releasing a spring, and discharging the preparation. A study in crab-eating monkeys (Macaca fascicularis) showed that the radionuclide in the small intestine circulated through the superior mesenteric vein to the portal vein and liver. Portal scintigraphy through the small intestine could be analysed in the same way as per-rectal portal scintigraphy, in which blood flow mostly from the inferior mesenteric vein is evaluated. A study of four volunteers showed that, after the radionuclide was released, it circulated through the superior mesenteric vein to the portal vein and liver. Use of a capsule enclosing a radioisotope was possible, and the procedure seemed to be safe. The use of the per-small intestine method plus the per-rectal method should give more accurate results than either method used alone, because the haemodynamics of both the superior and inferior mesenteric vein would be reflected.     

Marked uptake of technetium-99m pertechnetate by parathyroid adenoma.

We herewith report an unusual case of primary hyperparathyroidism whose parathyroid adenoma strongly accumulated technetium (Tc)-99m pertechnetate. A 41-year-old woman was referred to our department under the tentative diagnosis of primary hyperparathyroidism. Scintigraphy by thallium-201 chloride showed homogeneous uptake in the whole thyroid, whereas Tc-99m image revealed a strong local accumulation in the middle portion of the right thyroidal lobe. Neck exploration revealed a 12x8x5 mm tumor in the posterolateral region of the right thyroidal lobe, the pathology of which was parathyroid adenoma. In addition, a small nodule (8 mm in diameter) with pathological findings revealing follicular adenoma of the thyroid, was found within the medial portion of the right thyroidal lobe. Both lesions were removed by surgery, and a postoperative Tc-99m scintigraphy no longer demonstrated a significant uptake in the right thyroidal lobe. Since the thyroid adenoma was too small to be detected by any scintigraphic study and located much closer to the median line than the site of the marked accumulation of Tc-99m pertechnetate, it was considered very likely that the parathyroid adenoma concentrated Tc-99m. Search of literature revealed that there have been only thirteen cases of parathyroid tumor reported to date which significantly accumulated Tc-99m pertechnetate. The present patient represents another rare case of parathyroid adenoma showing sueh an unusual scintigraphic image.     

Single photon emission computed tomography to determine effective hepatic blood flow and intrahepatic shunting

The noninvasive determination of effective hepatic blood flow, intrahepatic shunted blood flow, intrahepatic shunt index, and total hepatic blood flow was investigated by using the sequential single photon emission computed tomography. This method was performed for a period of 10 minutes following an intravenous injection of ^99mTc-(Sn)-N-pyridoxyl-5-methyltryptophan and a venous blood sampling. This study comprised 8 healthy volunteers, 16 patients with chronic hepatitis, and 33 patients with liver cirrhosis. The intrahepatic shunt index measured with this method coincided with the intrahepatic shunt index determined by catheterization, indicating the high reliability of this procedure. The effective hepatic blood flow in patients with liver cirrhosis was significantly lower than that in the healthy controls and the chronic hepatitis group. The intrahepatic shunted blood flow was significantly higher in patients with liver cirrhosis compared with the flow in healthy controls. The intrahepatic shunt index was also significantly higher in patients with liver cirrhosis compared with the index of healthy controls and those with chronic hepatitis. No substantial differences were noted in the total hepatic blood flow among the three groups. The effective hepatic blood flow, the intrahepatic shunted blood flow, and the intrahepatic shunt index, correlated with the serum albumin concentration, the serum cholinesterase level, and the plasma indocyanine green attenuation rate. From these results, it was concluded that the present procedure constitutes a reliable and effective method for the noninvasive determination of hepatic blood flows. Consequently, it will be of high clinical value for assessing the functional and the pathological alterations of the liver.     

Effects of Esophageal Transection Combined with Splenectomy on Portal Hemodynamics

Portal hemodynamics were studied in 69 patients with cirrhosis and 29 patients with idiopathic portal hypertension to investigate the effects of an operative procedure for varices that consists of transabdominal esophageal mucosal transection, paraesophagogastric devascularization, pyloroplasty, and splenectomy. Portal venous flow measured by the pulsed Doppler flowmeter in 14 patients with cirrhosis and nine patients with idiopathic portal hypertension, who underwent operation 2-5 yr earlier, was significantly reduced compared with that in unoperated 49 patients with cirrhosis and 17 patients with idiopathic portal hypertension who had esophageal varices (410 +/- 158 versus 660 +/- 263 ml/min in cirrhosis; 443 +/- 185 versus 912 +/- 189 ml/min in idiopathic portal hypertension). In nine patients (six cirrhosis, three idiopathic portal hypertension), portal venous flow and portal vein pressure were measured before and after operation. In patients with cirrhosis, portal vein pressure did not change significantly postoperatively even though portal venous flow was reduced. In contrast, portal vein pressure decreased in two patients with idiopathic portal hypertension in whom portal venous flow was reduced. Portal vein pressure was elevated in one patient with idiopathic portal hypertension in whom portal venous flow was increased postoperatively as a result of resection of a large gastro- and splenorenal shunt conducted additionally.     

Portal hemodynamics in idiopathic portal hypertension (Banti's syndrome). Comparison with chronic persistent hepatitis and normal subjects

A comparative study of portal hemodynamics was made in 17 patients with idiopathic portal hypertension, 5 patients with chronic persistent hepatitis having no portal hypertension, and 21 healthy adults who served as the control for certain measurements. Venous pressures were measured by portal and hepatic vein catheterizations, blood flow by the pulsed Doppler flowmeter, organ volume by computed tomography, and intrahepatic shunt index by 99mTc-macroaggregated albumin instilled in the portal vein. The patients with idiopathic portal hypertension were divided into two groups: group A (n = 8) and group B (n = 9), consisting of those who respectively had portal venous flow per liver volume above and below the mean + 2 SD of healthy adults. In group A, portal vein pressure was moderately elevated, portal venous flow was significantly increased compared with the control, and portal vascular resistance was not much altered. In group B, portal vein pressure was markedly elevated above that of control, portal venous flow was comparable, and portal vascular resistance was significantly elevated. Splenic venous flow measured in the splenic vein between the left and short gastric veins was markedly increased in groups A and B, the increase being greater in the former. It was concluded that in some patients with idiopathic portal hypertension, increased portal venous flow, partly a result of increased splenic venous flow secondary to splenomegaly of an undetermined process, is the main contributor initially to the elevation of portal vein pressure; in others, possibly later, increased portal vascular resistance plays an important role.