Transient Hepatic Attenuation Differences Research Articles

Impact of transient hepatic attenuation differences on computed tomography scans in the diagnosis of acute gangrenous cholecystitis.

We examined the utility of transient hepatic attenuation differences (THADs) detected in the arterial phase of computed tomography for the diagnosis of acute gangrenous cholecystitis (AGC). We examined 83 consecutive patients who underwent cholecystectomy within 72h of undergoing three-phase dynamic computed tomography scans for acute cholecystitis between 2009 and 2018 (histopathological examination later confirmed 42 with AGC, 41 without). The THAD volume (cm3 ) was calculated by multiplying the total area of the enhancing lesions (traced on axial images) by the thickness of the scan (0.5-cm slices). We evaluated the sensitivity and specificity of the THAD volume and other computed tomography findings of AGC. The THAD volume was significantly larger in the AGC group than in the non-gangrenous acute cholecystitis group (P < 0.0001). The cutoff value of 78cm3 , determined using a receiver operating characteristics curve, yielded a sensitivity of 88.1% and specificity of 75.6% for detecting AGC. Multivariate analysis revealed a THAD volume of >78cm3 to be an independent predictor of AGC. Acute gangrenous cholecystitis can be diagnosed using THAD volume, resulting in improved treatment and fewer serious complications.

Diagnostic accuracy of MDCT in differentiating gallbladder cancer from acute and xanthogranulomatous cholecystitis

ObjectiveTo determine the diagnostic accuracy of multi-detector CT (MDCT) for differentiating gallbladder cancer from acute and xanthogranulomatous cholecystitis using previously described imaging features. MethodsIn this IRB approved HIPAA-compliant retrospective cohort study, contrast-enhanced MDCT of histologically confirmed acute cholecystitis (n = 17), xanthogranulomatous cholecystitis (n = 25), and gallbladder cancer (n = 18) were reviewed independently by three abdominal radiologists blinded to outcome. The primary outcome was the diagnostic accuracy of MDCT for the differentiation of gallbladder cancer from cholecystitis (acute and xanthogranulomatous) using various imaging parameters. Kappa (κ) statistics and two-way mixed-model single-measure intra-class correlation statistics (ICC) were calculated for each imaging feature and the final radiologic diagnosis. ResultsInter-rater agreement was moderate to substantial (κ = 0.43–0.70), sensitivity 0.67–0.78, specificity 0.22–0.33 and the positive likelihood ratio was 4.28–8.56 for the differentiation of gallbladder cancer from benign gallbladder pathology. Only three imaging findings: disrupted gallbladder mucosa (κ = 0.68), intraluminal gallstones (κ = 0.66), and gallbladder wall thickness (ICC = 0.63) had substantial inter-rater agreement. The following had slight or no agreement: intramural hypoattenuating nodules (κ = 0.17), transient hepatic attenuation differences (κ = 0.14), gallbladder wall calcification (κ = −0.01), gallbladder wall enhancement (κ = 0.18), and omental or mesenteric invasion (κ = 0.08). In the final multivariate model, the following were significant predictors useful in making or excluding diagnosis of gallbladder cancer: focal gallbladder wall thickening (p = 0.003, OR: 13.09 [95% CI: 2.40–71.48]), pericholecystic “fat stranding” (p = 0.018, OR: 0.10 [95% CI: 0.01–0.66]), and maximum short axis lymph node diameter (p = 0.043, OR: 1.18 [95% CI: 1.00–1.38]). ConclusionMDCT has moderate sensitivity, poor specificity, and moderate-to-substantial inter-rater repeatability for the differentiation of gallbladder cancer from acute and xanthogranulomatous cholecystitis.

Superior vena kava obstrüksiyonu olan iki hastada geçici hepatik kontrastlanma farklılığı: Bilgisayarlı tomografi bulguları

Radiographic appearances of transient hepatic attenuation differences (THAD) can mimic tumors. THAD can occur as a result of altered hemodynamics of the hepatic blood flow. Tumoral or non-tumoral processes can play role in the etiology. THADs that appear secondary to the obstruction of the superior vena cava are rarely seen. Herein, we present computed tomography findings of two cases with THAD secondary to superior vena cava obstruction

The Impact of Transient Hepatic Attenuation Differences in the Diagnosis of Pseudoaneurysm and Arteriovenous Fistula on Follow-Up CT Scans after Blunt Liver Trauma.

A feared complication to liver trauma is delayed vascular complication, such as pseudoaneurysm and arteriovenous fistula (PS/AF) seen as focal enhancement on contrast-enhanced computed tomography (CT) in the arterial phase. A hyperdense area termed transient hepatic attenuation difference (THAD) representing altered hepatic blood flow can be seen in the arterial phase near the liver lesion. The objective of this study was to describe THAD and PS/AF on follow-up CT after blunt liver trauma, and to evaluate if THAD influenced the evaluation of PS/AF. Three radiology residents retrospectively evaluated scans of 78 patients. The gold standard for PS/AF was an evaluation by an experienced senior radiologist, while THAD was a consensus between the residents. PS/AF was present in 14% and THAD in 54%. THAD was located in the periphery of the lesion with hazy borders and mean HU levels of 100, while PS/AF was located within the lesion with focal enhancement and mean HU levels of 170 (p < 0.05). In evaluation of PS/AF, the likelihood of agreement between the observers and the gold standard was 89% when THAD was present, and 98% when THAD was absent (p = 0.04). THAD is common and can hamper the evaluation of PS/AF.

Diagnostic accuracy of transient hepatic attenuation differences on computed tomography scans for acute cholangitis in patients with malignant disease.

Few reports have assessed the accuracy of transient hepatic attenuation differences (THAD) in the arterial phase of computed tomography (CT) in diagnosing acute cholangitis (AC). We examined the diagnostic accuracy of THAD in AC in patients with malignant disease. We retrospectively examined the records of 123 consecutive patients (73 men, 50 women; mean age, 69 [range, 43-91] years) who underwent dynamic CT 3 days before biliary drainage for malignant hepatobiliary disease between 2006 and 2011. We examined the diagnostic ability of THAD for AC and assessed the relationship between THAD and AC severity. Acute cholangitis was present in 45% of patients. The sensitivity and specificity of THAD for AC were 93% and 39%, respectively. Diffuse, hemi-hepatic, and segmental THAD for AC were seen in 84%, 4%, and 9%, respectively. In all, 64% of patients were diagnosed with severe AC and 29% with mild AC, depending on the intensity of THAD, but the patterns and degree of intensity of THAD and AC severity were not related. Although the pattern and the degree of intensity of THAD and AC severity were not related, THAD might be useful in diagnosing AC. Thus, THAD should be considered a diagnostic criterion for AC.

MDCT diagnosis of post-traumatic hepatic arterio-portal fistulas

The purpose of this study is to evaluate the performance of multidetector computed tomography (MDCT) in diagnosing arterioportal fistulas (APF) in high-grade liver injury. A retrospective analysis of catheter-based hepatic angiograms performed for major penetrating and blunt liver injuries identified 11 patients with APFs. Using the trauma registry, two additional demographically matched groups with and without liver injury were formed. A randomized qualitative consensus review of 33 MDCTs was performed by three trauma radiologists for the following MDCT findings of APF: transient hepatic parenchymal attenuation differences (THPAD), early increased attenuation of a peripheral or central portal vein compared with the main portal vein, and the "double-barrel" or "rail tract" signs. THPAD was the most sensitive finding and also had a high specificity for diagnosing APF. Both the early increased attenuation of a peripheral or central portal vein compared with the main portal vein and the double-barrel or rail tract signs had a100% specificity and a sensitivity of 64% and 36%, respectively. Measurement of differences in attenuation values between the APF and the contralateral central portal vein was most sensitive and specific in diagnosing APF. Traumatic APF of the liver can be optimally diagnosed with arterial phase imaging of solid organ using MDCT.

Comparison of the clinical characteristics and imaging findings of acute cholangitis with and without biliary dilatation

To evaluate the causes of acute cholangitis without biliary dilatation and to compare the clinical characteristics and the imaging findings between patients with acute cholangitis with and without biliary dilatation. 93 patients diagnosed with acute cholangitis underwent contrast-enhanced CT. Among them, 17 patients were classified as not having biliary dilatation (Group 1) and 76 patients were classified as having biliary dilatation (Group 2). The causes of acute cholangitis were evaluated in both groups. Clinical characteristics and imaging findings were compared between the two groups. The causes of acute cholangitis without biliary dilatation included common bile duct (CBD) stones (n=11), CBD sludge (n=3), a passed stone (n=1) and unknown causes (n=2). The total bilirubin levels of Group 1 were significantly lower than those of Group 2 (p=0.001). By contrast, Group 1 had higher median alanine aminotransferase (ALT) levels than Group 2 (p=0.04). The length of hospital stay was significantly longer in Group 2 than in Group 1 patients (p<0.001). In the imaging findings, the extent of transient hepatic attenuation differences (THADs) (p=0.003) were significantly smaller in Group 1 than in Group 2. CBD stones and sludge were the most common causes of acute cholangitis in patients without biliary dilatation. These patients showed lower levels of bilirubin and higher levels of ALT than those with acute cholangitis with biliary dilatation, and had a shorter duration of hospital stay. The extent of THADs was the only discriminative CT finding between the two groups. Acute cholangitis can present without biliary dilatation on imaging, and the most common causes are CBD stones and sludge. The patients with acute cholangitis without biliary dilatation have different clinical characteristics and imaging findings compared with those with acute cholangitis presenting with biliary dilatation.

Hepatic nodular regenerative lesions in patients with hereditary haemorrhagic telangiectasia: computed tomography and magnetic resonance findings

This study was done to evaluate the prevalence of regenerative hepatic nodules in patients with hereditary haemorrhagic telangiectasia (HHT). Between February 2001 and December 2010, 171 consecutive HHT patients (95 men and 76 women) were studied with triphasic multidetector computed tomography (MDCT) in 91 cases, magnetic resonance imaging (MRI) in 34 cases and both in the remaining 46 cases. The presence of diffuse vascular abnormalities and focal liver lesions were recorded. Hepatic arteriovenous malformations (HAVMs) were found in 126/171 (74%) patients. Arteriovenous shunts were found in 24/171 (14%) cases, arterioportal shunts in 52/171 (30%), mixed shunts in 26/171 (15%), telangiectases in 84/171 (49%) and transient hepatic attenuation differences (THADs) in 70/171 (41%). Hepatic nodular lesions were found in 6/171 (3.5%) patients (three men; three women). In 5/6 cases, vascular abnormalities were also evident. Two patients had a single lesion; four had multiple lesions. No lesion showed a central scar. Hyperenhancing hepatic regenerative lesions have a high prevalence in HHT patients, representing the response of liver parenchyma to hypoperfusion caused by HAVMs. These lesions are often multiple and may lead to nodular regenerative hyperplasia.

Dynamic 4D MR angiography versus multislice CT angiography in the evaluation of vascular hepatic involvement in hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber disease, is a rare autosomal dominant disorder characterised by mucocutaneous or visceral vascular abnormalities that may be widely distributed throughout the cardiovascular system. The purpose of this study was to compare multislice computed tomography angiography (MSCTA) and 4D dynamic contrast-enhanced magnetic resonance angiography (D-MRA) for evaluating vascular hepatic involvement in patients with HHT. Fifty-two consecutive HHT patients underwent MSCTA and D-MRA examinations for systematic analysis of vascular visceral involvement. The images from the two techniques were reviewed independently by two expert radiologists to identify the following vascular abnormalities: telangiectases or large vascular masses; perfusion disorders [transient hepatic attenuation differences (THADs)]; hepatic arteriovenous malformations (HAVMs). Data, as well as diameters of the common hepatic artery and portal vein, were compared with Cohen's kappa statistic, Student's t test and receiver operating characteristic (ROC) curve analysis, as appropriate. Both MSCTA and D-MRA detected one or more of the following hepatic vascular abnormalities in 36/52 cases (telangiectases in 29/52, THADs in 23/52 and HAVMs in 25/52[CE1]). A good concordance was found between the two techniques when determining the type of hepatic shunt (κ=0.9). No statistically significant differences were found when comparing mean common hepatic artery and portal vein diameters (p=0.09 and 0.22, respectively) and their accuracy in predicting HAVMs. D-MRA has the same diagnostic accuracy as MSCTA and has the advantage of being less invasive due to the absence of ionising radiation.

Diffuse Pattern of Transient Hepatic Attenuation Differences in Viral Hepatitis

Our objective was to describe the transient hepatic attenuation differences (THADs) on dynamic computed tomography in patients with viral hepatitis who had no evidence of cirrhosis. After excluding patients who had known causative factors for the development of THAD, a retrospective review of dynamic CT scans in 67 patients with viral hepatitis was performed to determine whether THAD was present. The patients were assigned to 3 groups according to the magnitude of alanine aminotransferase (ALT) level alteration (normal to mild, moderate, and marked) or hepatitis type (acute hepatitis, acute exacerbation of chronic hepatitis, and chronic infection), and differences in the presence of various CT features including THAD among these groups were evaluated. Five THADs observed had a focal pattern, and 18 THADs had a diffuse pattern. All of the diffuse THADs were observed in patients with marked ALT level alteration (ALT level > 400 IU/L) and in patients with a clinical diagnosis of acute hepatitis or acute exacerbation of chronic hepatitis. In addition, there were significant differences of the presence of other CT findings including hepatomegaly, periportal tracking, gallbladder wall thickening, perihepatic lymphadenopathy, and splenomegaly among these groups (each P < 0.05). A diffuse THAD of the liver and other CT features indicates acute hepatic injury in patients with viral hepatitis who have no clinical evidence of cirrhosis.

Giant area of transient hepatic attenuation difference, mimicking incidentaloma at liver ultrasound

Concurrent with recent advances in diagnostic imaging techniques, the incidental finding of liver tumors, or incidentalomas, is increasing in asymptomatic and healthy individuals [1]. A 56-year-old healthy man underwent an abdomen ultrasound for a clinical check-up. A diffuse bright liver echo-pattern (indicating a low-moderate grade steatosis) and an unusual image (diameter approximately 10 cm) in the VI–VII hepatic segment, characterized by a massive giant hypoechoic lesion with poorly defined margins and a near rounded hyperechoic area (diameter about 4 cm) in the context were found (Fig. 1). The ultrasonographer suspected an angioma as first diagnostic hypothesis; however the large hypoechoic area around it, was not unique interpretation. In order to clarify the nature of the lesion, a contrast-enhancement examination was indicated to exclude an incidentaloma. Contrast-enhanced ultrasound revealed an irregularly circular lesion, characterized by early arterial nodular enhancement with delayed centripetal fill-in during the arterial phase. At 36 seconds, the lesion had almost completely filled in. At 45 seconds, the lesion was completely enhanced and sustained enhancement was observed in the late phase scan. The picture was suggestive for hepatic angioma (Fig. 2). Contrast-enhanced MultiSlice computed tomography (CT scan) (Fig. 3) was performed to confirm the diagnosis that proved to be an angioma in the VI hepatic segment (diameter about 4.6 cm), revealing in contour a segmental area of transiently increased enhancement during the arterial phase, with isodense aspect to hepatic parenchyma on venous phase thus suggesting transient hepatic attenuation differences (THAD). THAD is a hepatic perfusion anomaly, caused by an aberrant dual blood supply associated with numerous liver disorders, and it is visible on a contrast-enhanced biphasic spiral CT scan as parenchymal areas of high attenuation in the arterial phase, becoming an isodense image with the normal parenchyma in the portal venous phase [2]. Occasionally, attenuation differences may persist up to the portal venous phases due to a concurrent obstruction of a hepatic vein branch. THADs can be confused with tumor lesions, and are a compensatory relationship between two liver sources of blood supply so that the arterial flow increases as the portal flow decreases. In other words, this particular condition, also called steal syndrome, is seen when there are extensive anastomoses between two vascular beds, and the arterial supply to one is stenosed or occluded, resulting in diversion of blood to the other vascular bed. This is a result of communication between the main vessels, sinusoids, and peribiliary venules, which open in response to the autonomic nervous system, and humoral factors activated by the liver’s demand for oxygen and metabolites. These lesions do not cause a mass effect on the vascular structures, and normal hepatic vascular structures can be seen passing through them. The lesions can be encountered in an entire lobe (lobar), segment (segmental), subsegment (subsegmental) or in a sub-capsular area of the liver. THADs may be noted to accompany hypervascular tumors, generally malignant but also benign (hepatocellular carcinoma, hypervascular metastases, cholangiocarcinoma, hemangioma, focal nodular hyperplasia, pyogenic abscess and focal eosinophilic necrosis) due to a steal syndrome [3]. However, they may also occur in patients without hepatic focal G. Parrinello D. Torres (&) G. Licata Biomedical Department of Internal and Specialty Medicine, Di.Bi.Mi.S., Internistic and Cardiovascular Diagnostic Ultrasound Laboratory, A.O.U Policlinico Paolo Giaccone, University of Palermo, Piazza delle Cliniche 2, 90127 Palermo, Italy e-mail: daniele_torres@libero.it

Transient hepatic attenuation differences in neonates

Transient hepatic attenuation differences in neonates

Understanding Transient Hepatic Attenuation Differences

Transient hepatic attenuation differences (THADs) are the imaging manifestation of regional variations in the balance between hepatic arterial, portal venous, and third inflow sources of hepatic blood flow. THADs are typically wedge-shaped hypervascular regions visible on the hepatic arterial phase, and fade to isodense on venous and delayed phases. They are commonly seen in the setting of locally diminished portal venous inflow. Familiarity with the characteristic appearance and the physiology of THADs should permit discrimination of these fascinating pseudolesions from true space occupying masses.

Transient hepatic attenuation differences in neonates

A transient hepatic attenuation difference (THAD) is a hepatic perfusion anomaly seen on contrast-enhanced CT scans caused by an alteration in the dual blood supply of the liver. Although THADs have been described in adolescents and adults, they have not previously been described in neonates. We describe the appearance and evaluate the frequency of THADs in neonates < or =1 month of age compared to other infants younger than 2 years. A retrospective study was performed looking at all CT angiograms from 2000 to 2007 in infants <2 years of age. The incidence of THADs was compared among four age groups. Significance was determined using a logistic regression model. The study included 128 CT angiograms. A THAD was seen in 9/26 infants <1 month of age, in 3/50 infants 1 to 6 months of age, in 1/23 infants 6 months to 1 year of age, and in 1/29 infants 1 to 2 years of age. A THAD was found significantly more frequently in infants <1 month of age than in the older age groups (P<0.05). THADs are benign entities that can be seen normally in the neonatal age group. When the characteristic appearance is seen on CT, no further imaging is needed.

Transient Hepatic Attenuation Differences and Focal Liver Lesions

To analyze at computed tomography (CT) examination the "sump effect," a particular type of transient hepatic attenuation differences, related primarily to an increase in arterial flow without any accompanying decrease in portal flow. We retrospectively evaluated all biphasic upper abdomen CT examinations (1283 in 807 patients) performed from the year 2003 to the year 2006 and selected and organized those with at least 1 transient hepatic attenuation differences. Of these, we enrolled patients with lobar/multisegmental arterializations surrounding focal lesion(s), without CT portal hypoperfusion signs, in the study group. We assessed histology, number, site, diameter, and volume of causing focal lesion(s); site, extension, and attenuation of arterial area; greater visibility of feeding artery branches ipsilateral to causal focal lesion; and presence of aberrant left hepatic artery. Thirty patients with normal liver represented the control group. Fifteen of the 99 patients with transient hepatic attenuation differences presented with sump effect. In our series, this phenomenon was always related to hypervascular inflammatory and benign lesion(s) with overall average diameter of 8 +/- 4 cm inscribed in arterial area. Attenuation of arterial enhanced areas were significantly higher than the contralateral parenchyma and control patients' parenchyma, with frequent hypertrophy of ipsilateral arterial feeding branches and/or aberrant left hepatic artery visibility. Siphonage seems to be primary hyperperfusion area determined by arterial bed enlargement, induced by inscribed large hypervascular inflammatory/benign lesion(s).

Transient Hepatic Echogenicity Difference on Contrast-Enhanced Ultrasonography

The purpose of this study was to report and analyze a new contrast-enhanced ultrasonographic (CEUS) imaging finding, the transient hepatic echogenicity difference due to perfusion changes, using computed tomography (CT) as a reference standard. We retrospectively investigated the records of patients evaluated in a 2-year period, selecting those who had undergone both CT and CEUS within 15 days, who had CT evidence of a perfusion abnormality, and who had had a CEUS study that included the malperfused parenchymal area. There were 30 patients with 44 hepatic perfusion changes on CT scans (28 around liver focal lesions and 16 unrelated to focal lesions). Retrospectively, CEUS allowed recognition of 21 of 28 perifocal transient hepatic attenuation differences (THADs), 6 of 10 subsegmental THADs, 2 of 3 segmental THADs, and 1 of 3 lobar THADs. Only some of these abnormalities had been identified at the original CEUS examinations: 0 of 3 lobar THADs, 1 of 3 segmental THADs, 2 of 10 subsegmental THADs, and 16 of 28 perifocal THADs. Contrast-enhanced ultrasonography can show hepatic perfusion abnormalities similar to those well known from CT literature, although with a lower sensitivity. Knowledge of this transient hepatic echogenicity difference phenomenon may be relevant for avoiding incorrect image interpretation or incorrect tumor size measurement and for eventually identifying occult vascular disorders such as venous thrombosis or fistulas.

Transient Hepatic Intensity Differences: Part 1, Those Associated with Focal Lesions

The purpose of our study was to evaluate, on MRI, transient hepatic signal intensity differences (THID) that have already been seen on CT as transient hepatic attenuation differences (THAD) and to show the range of appearance of such arterial phenomena, when associated with focal lesions, in an effort to correlate morphology, cause, and pathogenesis. Hepatic arterial phenomena visualized on MRI should be known and recognized to avoid incorrect diagnoses and to improve the characterization of focal liver lesions because their shape can lead to an understanding of pathogenetic mechanisms.

Transient hepatic attenuation differences.

Transient hepatic attenuation differences.

Experimental clonorchiasis in dogs: CT findings before and after treatment.

To determine whether disease activity in clonorchiasis can be assessed with dynamic computed tomography (CT). Ten dogs infected with metacercariae of Clonorchis sinensis underwent serial dynamic CT examinations. Five dogs were sacrificed 14 weeks after infection, and another five infected dogs were treated with praziquantel at the 14th week and continued to undergo CT examinations until death or sacrifice at the 25th (n = 1) or 40th week (n = 4). CT images were evaluated for dilatation of the bile ducts, contrast enhancement of bile duct walls and adjacent hepatic parenchyma, visualization of flukes within the bile ducts, and presence of calcifications. Changes in CT findings were analyzed statistically by using a mixed linear model and a generalized estimating equations model. Dilatation of the bile ducts, contrast enhancement of the ductal walls, transient hepatic attenuation differences, and flukes per se were observed at CT from the 2nd through the 5th week, were most apparent between the 5th and 13th weeks, and disappeared or decreased markedly in degree after treatment in all dogs (P <.05). Nodular calcifications were observed at CT after treatment in two dogs. Histopathologic examination revealed proliferation and enlargement of arteries in the periductal area and the portal tracts and congestion of hepatic sinusoids during the acute phase. Treatment was associated with periductal hyalinization, degeneration of the periductal arteries, and calcification of the ductal epithelium. Disease activity in experimental canine clonorchiasis can be assessed with dynamic CT.

Temporal CT changes after hepatic and renal interstitial radiotherapy in a canine model.

The purpose of this work was to define the temporal CT characteristics of hepatic and renal ablation following point-source radioablation utilizing a low energy, photon X-ray source emitted from a miniature probe. Twelve mongrel dogs underwent each of three hepatic and two renal point-source radiation ablations. Animals underwent serial, dual phase, spiral CT scans and were killed at 1, 3, and 6 months after treatment. Ablative lesions were clearly visible at 1 month following therapy and consistently diminished in size over the 6 months of follow-up. Lesion size tended to be proportional to dose delivered. Both hepatic and renal lesions were low in attenuation with frequent rim enhancement that diminished over time. Hepatic lesions frequently showed transient hepatic attenuation differences (THADs). Lesion size appeared independent of proximity to vessels. Following hepatic or renal interstitial radiotherapy, lesions are generated that are similar in CT appearance to those produced by other ablative techniques. The presence of rim or THAD enhancement can be seen early on as part of the normal tissue-healing response.