European Journal of Cardiovascular Medicine

Focal liver lesions have a wide range of differential diagnoses to consider. HCC ranks sixth in over all incidence after lung, breast, prostate, colorectal and gastric cancer. It ranks 3 for both genders in terms of mortality Differentiating between different liver lesions is thought to be essential for choosing a course of treatment. ^[1] Both rates of incidence , mortality are 2–3 times more in men compared to women. The chosen liver imaging approach should have good lesion characterisation skills and high specificity and sensitivity for lesion identification in order to differentiate between lesions those require additional diagnostic testing or treatment from those do not require. ^[2] However, liver masses are becoming more widely recognised due to the increased use of imaging technologies On a routine radiograph, hepatic lesions are not visible until they are calcified. ^[3]

The most common investigation for diagnosing primary liver lesions is an ultrasonography (USG). However, in most cases, a mass found on ultrasound is then examined with contrast-enhanced CT scan (CECT) or MRI for precise characterization in order to provide a definitive diagnosis. ^[4] The benefits of characterisation offered by CT are greater, and it offers useful preoperative information. Despite recent study showing that MRI had a similar incidence of detecting and classifying localised liver lesions, CT was a superior imaging technique due to its rapid availability and short scanning times. ^[5]

Because it is well tolerated, the images have few artefacts, and the entire abdomen and pelvis may be examined swiftly within a single breath hold, CT is frequently selected for the first workup of localised and diffuse liver disease. The capacity to image with wide detector arrays, low kilovoltage (kVp) settings, iterative reconstruction, dual energy CT (DECT), and now deep learning image reconstructions is result of rapid advancement of CT technology over the past ten years. ^[6] Now It is very crucial than ever to pay attention to imaging characteristics for the best assessment of liver disease. With development of MDCT, the liver may now be scanned with great temporal resolution. ^[7]

Trans axial cross sectional CT has been turned into a 3D imaging modality by advancements in multi-detector row helical CT (MDCT). Rapid hepatic imaging and the adoption of new imaging procedures were made possible by significant advancements (Z-axis coverage speed and longitudinal resolution), which were not attainable with single-slice spiral CT. ^[8] With the advent of thin sections, lesion detection has become more accurate, and the acquisition of almost isotropic images has allowed for the production of high-resolution datasets for multiplanar reformation. ^[9]

Thinner slice collimation, nearly isotropic resolution, and multiphasic imaging are benefits of MDCT. Greater contrast enhancement of the main vessels can be scanned during with shorter volume acquisition times and faster scanning times. The most effective primary non-invasive method for evaluating both benign and malignant hepatic lesions is MDCT. ^[10] It enables excellent hepatic structure evaluation as well as the visibility and identification of tiny and large hepatic lesions. With regard to hepatic neoplasms, MDCT precisely illustrates the tumour’s shape, and relationship to the organs and circulatory structures around it. ^[11]

A prospective and correlation study was conducted among 40 patients attending Department of Radio Diagnosis, Karuna Medical College, Chitoor Palakkad.  Clinically suspected focal liver lesion, or previous investigations depicted focal hepatic lesion with a non-specific appearance.

Method of collection of data:

Total 40 patients aged between 15-80yrs with clinically suspected focal liver lesions and previous images depicted focal hepatic lesions with non specific appearance.

They were evaluated with Siemens Somatom and findings are correlated with biopsy/surgical findings where ever applicable. The conspicuity, enhancement patterns of individual lesions after the CT examination were noted and these findings were further correlated with histopathology/surgical findings/USG/follow-up as applicable

INCLUSION CRITERIA:

Patients with clinical suspicion of focal liver Lesions.

Previous imaging studies depicted focal liver lesions with nonspecific appearance.

EXCLUSION CRITERIA:

1. All patients with the history of trauma and allergic to contrast agents were excluded from the study.
2. Paediatric age group and pregnants are excluded.

Triple phase CT Technique Patient position: Supine with their arms above their head

Scout: Diaphragm to iliac crests/ pelvis

Scan extent: Diaphragm to iliac crests/ pelvis

Scan direction: Craniocaudal

Contrast injection considerations (bolus tracking)

Monitoring slice (region of interest)

Level of the diaphragmatic hiatus or first lumbar vertebra at the aorta

Threshold 150 HU(Hounsfield units)

Volume 100-120 ml of non-ionic contrast at 3 to 5 ml/s (a higher flow rate will equal great enhancement)

STATISTICAL ANALYSIS:

Data was collected and compiled into Microsoft excel worksheet and analyzed using Microsoft excel and SPSS. Chi square test /Fisher Exact test has been used to find the significance of association of CT scan findings with Final diagnosis. Diagnostic statistics such as sensitivity, Specificity, PPV, NPV and Accuracy has been used to find the correlation of CT scan with final diagnosis.

Table 1: Age distribution of Patients (N = 40)

Table :2 Gender distribution of Patients (N=40)

In the study there was a male preponderance (58.5%) when compared to females (42.5%).

Table 3: Evaluation: Correlation of CT enhancement patters in the diagnosis of focal liver lesions with the final diagnosis

Triphasic CT enhancement patterns observed as 100% sensitive and specific in diagnosing all the cases of Abscess, Cysts, Intrahepatic CCA. Sensitivity of Triphasic CT enhancement patterns in diagnosing the following cases of focal liver lesions in HCC, Haemangioma, Metastases 95.2%,90.9%,84% respectively. 100% specificity in diagnosing most of the cases only when the individual lesion had typical enhancement pattern except for 97.5% Metastasis and 95.2% in HCC. 100% sensitivity and specificity for intrahepatic CCA observed in our study was due very small sample size and larger size (>3cm) of the lesion.

Table :4 Distribution of the focal liver lesions according to age in years

In the study maximum percentage of cases was seen in the age range of 41-60years. 58% of the patients with HCC were in the 60-69years age range and 42% were in 61-80 age range.  One case (100%) of intrahepatic Cholangiocarcinoma were in the age range of 41-60years. No cases of Adenoma and FNH was seen.

Hemangiomas and cysts were seen in all age groups, about 67% of cases of hemangioma and 75% cases of cysts were seen in age range of 41-60years. 67% cases of abscess was seen in patients < 40years and 33% in 41-60 years. In our study, there was a male preponderance (57.5%) when compared to females who accounted for (42.5%) of cases.

There was male preponderance in HCC (83%) and female predominance in Intrahepatic CCA (100%) and metastases (60%) when compared to males. Out of 12 cases of HCC there were 5 HBV infected, 1 HCV infected, and four DCLD cases. In 5 cases there is tumoral invasion of portal vein case of fibrolamellar variant HCC, and one case of multicentric HCC are there. Most of the cases of Haemangiomas (77%) were noted in females. Most of the cases of Abscess (67%) were noted in males.

In comparison to Shrestha jain^[12] et al study out of 84 focal liver lesions, benign focal liver lesions were 72(85.7%) and malignant lesions were 12 (14.3%). The diagnostic accuracy (efficiency) of MDCT was found to be 90.5% with predicted value (95% CI: 84.20-96.75%). For the hepatocellular carcinoma cases, highly significant agreement (p<0.001) was found between MDCT and biopsy techniques. The overall sensitivity, specificity, PPV, NPV and diagnostic accuracy for malignant lesions was found to be 83.3%, 97.2%, 83.3%, 97.2% and 95.2% respectively.

In comparision to Guladi G F ^[13] et al study -One hundred and twenty-six liverlesions were detected in 66 patients, four of 11 enhancement patterns (hyper/iso/iso, hypo/hyper/hyper, hyper/hyper/hyper, hyper/hyper/iso) were always referrable to benign diseases (hemangioma, focal nodular hyperplasia-FNH- adenoma). Four of 11 enhancement patterns (iso/iso/hypo, iso/hypo/hypo, hyper/hyper/hypo, hyper/hypo/hypo) were always referrable to malignant diseases (hepatocellular carcinoma-IHCC-metastases). The remaining two patterns (hypo/hypo/hypo, hypo/hypo/hyper) were observed in both benign and malignant diseases.

Benign lesions like FNH and Adenoma also can show this type of enhancing pattern, but not observed in the study 11 of 21 HCC presented as A(variegated)/A/A(delayed), enhancing pattern. In the study we had 10 patterns of enhancement, three of the 10 enhancement patterns were always due to benign lesions, another three of 10 enhancement patterns were always due to malignant lesions, and other 3 of the 10 enhancement patterns were due to both malignant and benign lesions.

We included one different enhancement pattern for the fibrolamellar variant which were not included in the study conducted by Marten S. van Leeuwen, MD, et al. In the study by Kim et al^[14] it was stated that about 40-60% of all small HCC’s don’t exhibit “wash-out” on portal phase, even though are hyper vascular on arterial phase, whereas about 17% of small HCCs can appear hypodense on portal-venous phase and isodense on arterial phase. The reason for this atypical presentation was thought because of the multiple step process in hepato carcinogenesis, during which it may cause decreased portal tracks before the proper recruitment of the unpaired arteries or there may be appearance of neo angiogenesis without loss of portal tracks. Application of ancilliary imaging features, application of CEUS or acquisition of specific MRI sequences are required for further differentiation and characterization of the nodules, this may provide us with more information regarding their function, vascularity and cellularity. ^[15,16]

According to a large, recent prospective study, which includes 296 observations in total of 240 patients, combining MRI and MDCT in LIRADS gives better diagnosis of HCC than MRI or MDCT alone

Hepatic Arterial Phase images are helpful in detecting hyper vascular lesions and are essential for characterization of large proportions of lesions. Images in the equilibrium /delayed phase help further characterisation of lesions The 10 enhancement patterns used to characterize the focal liver lesions in the study and further correlation with standard of reference were satisfactory. The Triphasic CT enhancement patterns were 100% sensitive and specific in diagnosing all cases of Abscess, Cysts and Intrahepatic CCA, however Triphasic CT enhancement patterns in HCC (sensitivity- 95.2 %), Hemangioma (sensitivity 90.9 %), Metastases (sensitivity- 84 %) was sensitive in diagnosing most of the cases

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