Recurrent inversion polymorphisms in humans associate with genetic instability and genomic disorders.

Unlike copy number variants (CNVs), inversions remain an underexplored genetic variation class. By integrating multiple genomic technologies, we discover 729 inversions in 41 human genomes. Approximately 85% of inversions <2 kbp form by twin-priming during L1 retrotransposition; 80% of the larger inversions are balanced and affect twice as many nucleotides as CNVs. Balanced inversions show an excess of common variants, and 72% are flanked by segmental duplications (SDs) or retrotransposons. Since flanking repeats promote non-allelic homologous recombination, we developed complementary approaches to identify recurrent inversion formation. We describe 40 recurrent inversions encompassing 0.6% of the genome, showing inversion rates up to 2.7 × 10-4 per locus per generation. Recurrent inversions exhibit a sex-chromosomal bias and co-localize with genomic disorder critical regions. We propose that inversion recurrence results in an elevated number of heterozygous carriers and structural SD diversity, which increases mutability in the population and predisposes specific haplotypes to disease-causing CNVs.

Assembly of 43 human Y chromosomes reveals extensive complexity and variation.

The prevalence of highly repetitive sequences within the human Y chromosome has prevented its complete assembly to date1 and led to its systematic omission from genomic analyses. Here we present de novo assemblies of 43 Y chromosomes spanning 182,900 years of human evolution and report considerable diversity in size and structure. Half of the male-specific euchromatic region is subject to large inversions with a greater than twofold higher recurrence rate compared with all other chromosomes2. Ampliconic sequences associated with these inversions show differing mutation rates that are sequence context dependent, and some ampliconic genes exhibit evidence for concerted evolution with the acquisition and purging of lineage-specific pseudogenes. The largest heterochromatic region in the human genome, Yq12, is composed of alternating repeat arrays that show extensive variation in the number, size and distribution, but retain a 1:1 copy-number ratio. Finally, our data suggest that the boundary between the recombining pseudoautosomal region 1 and the non-recombining portions of the X and Y chromosomes lies 500 kb away from the currently established1 boundary. The availability of fully sequence-resolved Y chromosomes from multiple individuals provides a unique opportunity for identifying new associations of traits with specific Y-chromosomal variants and garnering insights into the evolution and function of complex regions of the human genome.

Ultrasound-based predictive indicators for treatment outcomes in pediatric vesicoureteral reflux.

PURPOSE: To evaluate the effectiveness of preoperative ultrasound (US) measurements in predicting pediatric vesicoureteral reflux (VUR) treatment outcomes. METHODS: This prospective study enrolled 35 patients (53 renal units) aged 1-16 years who underwent subureteric injection therapy for primary VUR between July 2020 and June 2022. Preoperative ultrasound examinations measured the bladder wall thickness at the ureteral orifice, ureteral submucosal tunnel length, distal ureteral diameter, patient demographics, VUR grade, presenting complaints, bladder-bowel dysfunction, and renal scarring, and the impact of these variables on treatment success was analyzed. RESULTS: Among the patients, 91.4% were female, with a mean age of 6.83 ± 3.84 years. A comparison between the treatment success and failure groups revealed no significant differences in the age, sex, VUR grade, laterality, bilaterality, presenting complaints, bladder-bowel dysfunction, bladder wall thickness, or distal ureteral diameter (p > 0.05). However, renal scarring occurred in 16 (38.1%) patients in the treatment success group and 10 (90.9%) in the treatment failure group (p = 0.002). The treatment failure group had shorter detrusor-to-ureteral orifice distances and smaller detrusor-ureteral orifice distance-to-distal ureteral diameter (D/U) ratios than that of the success group (p = 0.004 and p = 0.006, respectively). Patients with a detrusor-to-ureteral orifice distance < 7.4 mm had an 81.82% likelihood of treatment failure. CONCLUSION: Ultrasound measurements of the detrusor-to-ureteral orifice distance and D/U ratio proved reliable in predicting the success of endoscopic subureteric injection therapy for VUR.

The 22q11 low copy repeats are characterized by unprecedented size and structural variability.

Low copy repeats (LCRs) are recognized as a significant source of genomic instability, driving genome variability and evolution. The Chromosome 22 LCRs (LCR22s) mediate nonallelic homologous recombination (NAHR) leading to the 22q11 deletion syndrome (22q11DS). However, LCR22s are among the most complex regions in the genome, and their structure remains unresolved. The difficulty in generating accurate maps of LCR22s has also hindered localization of the deletion end points in 22q11DS patients. Using fiber FISH and Bionano optical mapping, we assembled LCR22 alleles in 187 cell lines. Our analysis uncovered an unprecedented level of variation in LCR22s, including LCR22A alleles ranging in size from 250 to 2000 kb. Further, the incidence of various LCR22 alleles varied within different populations. Additionally, the analysis of LCR22s in 22q11DS patients and their parents enabled further refinement of the rearrangement site within LCR22A and -D, which flank the 22q11 deletion. The NAHR site was localized to a 160-kb paralog shared between the LCR22A and -D in seven 22q11DS patients. Thus, we present the most comprehensive map of LCR22 variation to date. This will greatly facilitate the investigation of the role of LCR variation as a driver of 22q11 rearrangements and the phenotypic variability among 22q11DS patients.

Subgroup analysis of accreta, increta and percreta cases using acoustic radiation force impulse elastography.

OBJECTIVE: To compare acoustic radiation force impulse (ARFI) elastography values and histopathological diagnoses (accreta, increta, percreta) in patients suspected of having abnormal placental invasion (API). MATERIALS AND METHODS: This prospective study included 54 patients in the third trimester with a history of caesarian section (CS) and API based on gray scale and Doppler ultrasonography (USG) and 35 healthy controls. Patients underwent ARFI elastography preoperatively. Elastography measurements of the fetal and maternal sides of the placenta were compared to histopathology. RESULTS: Patients had higher maternal-side, fetal-side and average elastography values (P = 0.001). Intraoperatively, eight patients (14.8%) showed abnormal cervical canal invasion and 46 (85.2%) bladder and/or parametrial invasion. Eight patients underwent CS + placental-bed suture, 11 CS + excision of the lower segment, and 35 caesarean-hysterectomy. Histopathology of lower segment excision/caesarian-hysterectomy patients determined 10 (21.7%) accreta, 10 (21.7%) increta and 26 (56.6%) percreta cases. ARFI values were highest in the percreta subgroup. The increta subgroup showed higher ARFI values than the accreta subgroup but maternal-side, fetal-side and average ARFI values were not significantly different across the subgroups (P > 0.05). The cut-off values for average, peripheral and central elastography were determined as >0.90, >0.76, >0.98 (m/s) with sensitivities of 98, 64, 98% and specificities of 85, 80, 91%, respectively. CONCLUSION: ARFI elastography can detect API. However, it cannot determine invasion depth reliably. More studies with subgroup analyses are warranted to reveal its usefulness for invasion depth.

Versatile design and synthesis platform for visualizing genomes with Oligopaint FISH probes.

A host of observations demonstrating the relationship between nuclear architecture and processes such as gene expression have led to a number of new technologies for interrogating chromosome positioning. Whereas some of these technologies reconstruct intermolecular interactions, others have enhanced our ability to visualize chromosomes in situ. Here, we describe an oligonucleotide- and PCR-based strategy for fluorescence in situ hybridization (FISH) and a bioinformatic platform that enables this technology to be extended to any organism whose genome has been sequenced. The oligonucleotide probes are renewable, highly efficient, and able to robustly label chromosomes in cell culture, fixed tissues, and metaphase spreads. Our method gives researchers precise control over the sequences they target and allows for single and multicolor imaging of regions ranging from tens of kilobases to megabases with the same basic protocol. We anticipate this technology will lead to an enhanced ability to visualize interphase and metaphase chromosomes.

Radiological findings and outcomes of bronchial artery embolization in cryptogenic hemoptysis.

Management of cryptogenic massive hemoptysis is difficult, and conservative treatment may be inadequate to stop the hemorrhage. Surgery is not a reasonable option because there is no underlying identifiable pathology. This study aimed to investigate the radiologic findings and bronchial artery embolization outcomes in cryptogenic hemoptysis, and to compare the results with non-cryptogenic hemoptysis. We evaluated 26 patients with cryptogenic hemoptysis and 152 patients with non-cryptogenic hemoptysis. A comparison of the bronchial artery abnormalities between the cryptogenic and non-cryptogenic hemoptysis groups showed that only extravasation was more statistically significant in the cryptogenic hemoptysis group than in the non-cryptogenic hemoptysis group, while the other bronchial artery abnormalities, such as bronchial artery dilatation, hypervascularity, and bronchial-to-pulmonary shunting, showed no significant difference between groups. Involvement of the non-bronchial systemic artery was significantly greater in the non-cryptogenic hemoptysis group than in the cryptogenic hemoptysis group. While 69.2% of patients with cryptogenic hemoptysis also had hypervascularity in the contralateral bronchial arteries and/or ipsilateral bronchial artery branches other than the bleeding lobar branches, this finding was not detected in non-cryptogenic hemoptysis. Embolization was performed on all patients using polyvinyl alcohol particles of 355-500 µm. Hemoptysis ceased in all patients immediately after embolization. While recurrence of hemoptysis showed no statistically significant difference between the cryptogenic and non-cryptogenic hemoptysis groups, it was mild in cryptogenic hemoptysis in contrast to mostly severe in non-cryptogenic hemoptysis. Transarterial embolization is a safe and effective technique to manage cryptogenic hemoptysis.

Endovascular management of vascular complications after percutaneous nephrolithotomy.

BACKGROUND: Bleeding is one of the most common and most important complications of percutaneous nephrolithotomy (PCNL), which is mainly controlled with conservative treatment options. Transcatheter arterial embolization is required in less than 1 % of the patients undergoing PCNL. There are only a few studies about endovascular treatment of vascular complications of PCNL. The purpose of this study was to evaluate renal arterial complications of PCNL and treatment outcomes with endovascular coil embolization. PATIENTS AND METHODS: This retrospective study evaluated 16 patients who underwent endovascular management for complications after PCNL, including diagnostic angiography. We analyzed the angiographic appearances of the vascular lesions that caused hemorrhages, treatment outcomes for endovascular coil embolization, and renal parenchymal loss rate following this treatment. RESULTS: Seven patients had a pseudoaneurysm, two patients had an arteriocaliceal fistula (ACF), five patients had a pseudoaneurysm and an arteriovenous fistula (AVF), and two patients had a pseudoaneurysm and an ACF. Of the 14 patients with pseudoaneurysms, five had more than one pseudoaneurysm. Endovascular coil embolization was successful in all patients, and it was able to stop the bleeding. After embolization, 12 patients had less than 10 % parenchymal loss, and 4 patients had 10-20 % parenchymal loss. Mean hospital stay after embolization was 2.3 ± 0.7 days (range, 1 to 3 days). CONCLUSIONS: The injuries seen in the intrarenal arterial system during the PCNL procedure can result in pseudoaneurysms and/or AVFs and/or ACFs, and more than one artery can be harmed. Arterial complications of PCNL can be treated with endovascular coil embolization while preserving renal function at a maximum level.

Structural polymorphism and diversity of human segmental duplications.

Segmental duplications (SDs) contribute significantly to human disease, evolution, and diversity yet have been difficult to resolve at the sequence level. We present a population genetics survey of SDs by analyzing 170 human genome assemblies where the majority of SDs are fully resolved using long-read sequence assembly. Excluding the acrocentric short arms, we identify 173.2 Mbp of duplicated sequence (47.4 Mbp not present in the telomere-to-telomere reference) distinguishing fixed from structurally polymorphic events. We find that intrachromosomal SDs are among the most variable with rare events mapping near their progenitor sequences. African genomes harbor significantly more intrachromosomal SDs and are more likely to have recently duplicated gene families with higher copy number when compared to non-African samples. A comparison to a resource of 563 million full-length Iso-Seq reads identifies 201 novel, potentially protein-coding genes corresponding to these copy number polymorphic SDs.

The Effect of Pneumococcal, Influenza, and COVID-19 Vaccinations on COVID-19 Hospitalization and Progression in People over 65 Years Old Living in Nursing Homes.

Infectious diseases pose a major threat to elderly populations. Streptococcus pneumonia bacteria, influenza-causing viruses, and COVID-19 viruses cause three pathologies in the respiratory system with similar symptoms, transmission routes, and risk factors. Our study aimed to evaluate the effects of pneumococcal, influenza, and COVID-19 vaccinations on the status of COVID-19 hospitalization and progression in people over 65 years of age living in nursing homes. This study was performed in all nursing homes and elderly care centers in the Uskudar district of Istanbul.The diagnosis rate of COVID-19 was determined as 49%, the rate of hospitalization as 22.4%, the rate of hospitalization in the intensive care unit as 12.2%. The rate of intubation was determined as 10.4%, the rate of mechanical ventilation as 11.1% and the rate of COVID-19 related mortality rate as 9.7%. When the factors affecting the diagnosis of COVID-19 were examined, the presence and dose of COVID-19 vaccine was protective. When the factors affecting hospitalization status were examined, male sex and presence of chronic disease were risk factors; four doses of COVID-19 vaccine and influenza vaccine and pneumococcal vaccine together with COVID-19 vaccine were protective. When the factors affecting COVID-19-related death were examined, the male sex was a risk factor; the pneumococcal and influenza vaccine together with COVID-19 vaccine were protective. Our results revealed that the availability of influenza and pneumococcal vaccines positively impacted the progression of COVID-19 disease in the elderly population living in nursing homes.

Ancient AMY1 gene duplications primed the amylase locus for adaptive evolution upon the onset of agriculture.

Starch digestion is a cornerstone of human nutrition. The amylase enzyme, which digests starch, plays a key role in starch metabolism. Indeed, the copy number of the human amylase gene has been associated with metabolic diseases and adaptation to agricultural diets. Previous studies suggested that duplications of the salivary amylase gene are of recent origin. In the course of characterizing 51 distinct amylase haplotypes across 98 individuals employing long-read DNA sequencing and optical mapping methods, we detected four 31mers linked to duplication of the amylase locus. Analyses with these 31mers suggest that the first duplication of the amylase locus occurred more than 700,000 years ago before the split between modern humans and Neanderthals. After the original duplication events, amplification of the AMY1 genes likely occurred via nonallelic homologous recombination in a manner that consistently results in an odd number of copies per chromosome. These findings suggest that amylase haplotypes may have been primed for bursts of natural-selection associated duplications that coincided with the incorporation of starch into human diets.

High level of complexity and global diversity of the 3q29 locus revealed by optical mapping and long-read sequencing.

BACKGROUND: High sequence identity between segmental duplications (SDs) can facilitate copy number variants (CNVs) via non-allelic homologous recombination (NAHR). These CNVs are one of the fundamental causes of genomic disorders such as the 3q29 deletion syndrome (del3q29S). There are 21 protein-coding genes lost or gained as a result of such recurrent 1.6-Mbp deletions or duplications, respectively, in the 3q29 locus. While NAHR plays a role in CNV occurrence, the factors that increase the risk of NAHR at this particular locus are not well understood. METHODS: We employed an optical genome mapping technique to characterize the 3q29 locus in 161 unaffected individuals, 16 probands with del3q29S and their parents, and 2 probands with the 3q29 duplication syndrome (dup3q29S). Long-read sequencing-based haplotype resolved de novo assemblies from 44 unaffected individuals, and 1 trio was used for orthogonal validation of haplotypes and deletion breakpoints. RESULTS: In total, we discovered 34 haplotypes, of which 19 were novel haplotypes. Among these 19 novel haplotypes, 18 were detected in unaffected individuals, while 1 novel haplotype was detected on the parent-of-origin chromosome of a proband with the del3q29S. Phased assemblies from 44 unaffected individuals enabled the orthogonal validation of 20 haplotypes. In 89% (16/18) of the probands, breakpoints were confined to paralogous copies of a 20-kbp segment within the 3q29 SDs. In one del3q29S proband, the breakpoint was confined to a 374-bp region using long-read sequencing. Furthermore, we categorized del3q29S cases into three classes and dup3q29S cases into two classes based on breakpoints. Finally, we found no evidence of inversions in parent-of-origin chromosomes. CONCLUSIONS: We have generated the most comprehensive haplotype map for the 3q29 locus using unaffected individuals, probands with del3q29S or dup3q29S, and available parents, and also determined the deletion breakpoint to be within a 374-bp region in one proband with del3q29S. These results should provide a better understanding of the underlying genetic architecture that contributes to the etiology of del3q29S and dup3q29S.

A Case of Euglycemic Diabetic Ketoacidosis due to Empagliflozin Use in a Patient with Type 1 Diabetes Mellitus.

Euglycemic diabetic ketoacidosis is characterised by serum blood glucose <250 mg/dl, arterial blood pH <7.35, and the presence of ketones in urine or blood. Here, we present a 36-year female with type-1 diabetes mellitus, a case of euglycemic diabetic ketoacidosis, who was admitted to the emergency unit with nausea, vomiting, and confusion after using empagliflozin, which was added to her treatment one month ago. She was followed up in the intensive care unit for four days. Empagliflozin was discontinued. Intravenous fluids and insulin infusions were given. The patient, whose metabolic acidosis regressed, was discharged with the necessary recommendations and training. Euglycemic diabetic ketoacidosis should be kept in mind as a differential diagnosis in patients with type-1 diabetes and type-2 diabetes presenting with acidosis. Attention should be paid to the patients' medications and whether there are SGLT-2 inhibitors among these drugs. Key Words: Diabetes mellitus, Sodium-glucose co-transporter-2 inhibitors, Euglycemic diabetic ketoacidosis, Empagliflozin.

Genome-wide analysis of copy number variants and normal facial variation in a large cohort of Bantu Africans.

Similarity in facial characteristics between relatives suggests a strong genetic component underlies facial variation. While there have been numerous studies of the genetics of facial abnormalities and, more recently, single nucleotide polymorphism (SNP) genome-wide association studies (GWASs) of normal facial variation, little is known about the role of genetic structural variation in determining facial shape. In a sample of Bantu African children, we found that only 9% of common copy number variants (CNVs) and 10-kb CNV analysis windows are well tagged by SNPs (r2 ≥ 0.8), indicating that associations with our internally called CNVs were not captured by previous SNP-based GWASs. Here, we present a GWAS and gene set analysis of the relationship between normal facial variation and CNVs in a sample of Bantu African children. We report the top five regions, which had p values ≤ 9.35 × 10-6 and find nominal evidence of independent CNV association (p < 0.05) in three regions previously identified in SNP-based GWASs. The CNV region with strongest association (p = 1.16 × 10-6, 55 losses and seven gains) contains NFATC1, which has been linked to facial morphogenesis and Cherubism, a syndrome involving abnormal lower facial development. Genomic loss in the region is associated with smaller average lower facial depth. Importantly, new loci identified here were not identified in a SNP-based GWAS, suggesting that CNVs are likely involved in determining facial shape variation. Given the plethora of SNP-based GWASs, calling CNVs from existing data may be a relatively inexpensive way to aid in the study of complex traits.

SvAnna: efficient and accurate pathogenicity prediction of coding and regulatory structural variants in long-read genome sequencing.

Structural variants (SVs) are implicated in the etiology of Mendelian diseases but have been systematically underascertained owing to sequencing technology limitations. Long-read sequencing enables comprehensive detection of SVs, but approaches for prioritization of candidate SVs are needed. Structural variant Annotation and analysis (SvAnna) assesses all classes of SVs and their intersection with transcripts and regulatory sequences, relating predicted effects on gene function with clinical phenotype data. SvAnna places 87% of deleterious SVs in the top ten ranks. The interpretable prioritizations offered by SvAnna will facilitate the widespread adoption of long-read sequencing in diagnostic genomics. SvAnna is available at https://github.com/TheJacksonLaboratory/SvAnn a .

Genome-wide copy number variations in a large cohort of bantu African children.

BACKGROUND: Copy number variations (CNVs) account for a substantial proportion of inter-individual genomic variation. However, a majority of genomic variation studies have focused on single-nucleotide variations (SNVs), with limited genome-wide analysis of CNVs in large cohorts, especially in populations that are under-represented in genetic studies including people of African descent. METHODS: We carried out a genome-wide copy number analysis in > 3400 healthy Bantu Africans from Tanzania. Signal intensity data from high density (> 2.5 million probes) genotyping arrays were used for CNV calling with three algorithms including PennCNV, DNAcopy and VanillaICE. Stringent quality metrics and filtering criteria were applied to obtain high confidence CNVs. RESULTS: We identified over 400,000 CNVs larger than 1 kilobase (kb), for an average of 120 CNVs (SE = 2.57) per individual. We detected 866 large CNVs (≥ 300 kb), some of which overlapped genomic regions previously associated with multiple congenital anomaly syndromes, including Prader-Willi/Angelman syndrome (Type1) and 22q11.2 deletion syndrome. Furthermore, several of the common CNVs seen in our cohort (≥ 5%) overlap genes previously associated with developmental disorders. CONCLUSIONS: These findings may help refine the phenotypic outcomes and penetrance of variations affecting genes and genomic regions previously implicated in diseases. Our study provides one of the largest datasets of CNVs from individuals of African ancestry, enabling improved clinical evaluation and disease association of CNVs observed in research and clinical studies in African populations.

Genomic regions associated with microdeletion/microduplication syndromes exhibit extreme diversity of structural variation.

Segmental duplications (SDs) are a class of long, repetitive DNA elements whose paralogs share a high level of sequence similarity with each other. SDs mediate chromosomal rearrangements that lead to structural variation in the general population as well as genomic disorders associated with multiple congenital anomalies, including the 7q11.23 (Williams-Beuren Syndrome, WBS), 15q13.3, and 16p12.2 microdeletion syndromes. Population-level characterization of SDs has generally been lacking because most techniques used for analyzing these complex regions are both labor and cost intensive. In this study, we have used a high-throughput technique to genotype complex structural variation with a single molecule, long-range optical mapping approach. We characterized SDs and identified novel structural variants (SVs) at 7q11.23, 15q13.3, and 16p12.2 using optical mapping data from 154 phenotypically normal individuals from 26 populations comprising five super-populations. We detected several novel SVs for each locus, some of which had significantly different prevalence between populations. Additionally, we localized the microdeletion breakpoints to specific paralogous duplicons located within complex SDs in two patients with WBS, one patient with 15q13.3, and one patient with 16p12.2 microdeletion syndromes. The population-level data presented here highlights the extreme diversity of large and complex SVs within SD-containing regions. The approach we outline will greatly facilitate the investigation of the role of inter-SD structural variation as a driver of chromosomal rearrangements and genomic disorders.

Knowledge and attitude evaluation of physicians and nurses on COVID-19.

OBJECTIVE: This study aims to evaluate the knowledge, perceptions, and attitudes of physician faculty members, nurses, and medical students who work in a hospital in Istanbul regarding COVID-19. METHODS: This cross-sectional study was conducted in a tertiary hospital from March 2 to March 10, 2020. The research data were collected through a survey consisting of 22 questions about their demographics and their level of knowledge, sources of information, actions, attitudes, and thoughts about COVID-19. The collected data were analyzed using SPSS 22.0. RESULTS: Out of 1.460 people, 614 (42%) participated in this study. More than 60% of the participants correctly answered the information questions about COVID-19. 72.6% of the participants stated that the situation that would stress them out the most in case of a COVID-19 outbreak in Turkey would be the diagnosis of one of their family members with COVID-19. Social media (66.4%) was the primary source of information in this process. CONCLUSION: The findings obtained in this study showed that right before the outbreak, healthcare professionals were concerned and stressed about the inadequacy of protective measures and the possibility of transmission, although they were ready for the outbreak in the professional sense.

Haplotype-resolved diverse human genomes and integrated analysis of structural variation.

Long-read and strand-specific sequencing technologies together facilitate the de novo assembly of high-quality haplotype-resolved human genomes without parent-child trio data. We present 64 assembled haplotypes from 32 diverse human genomes. These highly contiguous haplotype assemblies (average minimum contig length needed to cover 50% of the genome: 26 million base pairs) integrate all forms of genetic variation, even across complex loci. We identified 107,590 structural variants (SVs), of which 68% were not discovered with short-read sequencing, and 278 SV hotspots (spanning megabases of gene-rich sequence). We characterized 130 of the most active mobile element source elements and found that 63% of all SVs arise through homology-mediated mechanisms. This resource enables reliable graph-based genotyping from short reads of up to 50,340 SVs, resulting in the identification of 1526 expression quantitative trait loci as well as SV candidates for adaptive selection within the human population.

The role of acoustic radiation force impulse elastography in the differentiation of benign and malignant focal liver masses.

BACKGROUND/AIMS: The aim of this study was to evaluate elasticity of benign and malign focal liver lesions and surrounding parenchyma as measured by acoustic radiation force impulse (ARFI). MATERIALS AND METHODS: 34 hemangiomas, 4 focal nodular hyperplasia (FNH), 10 hepatocellular carcinoma (HCC) and 22 metastatic lesions from a total of 62 patients were examined with ARFI elastography. ARFI measurements for each tumor type were expressed as mean ± standard deviation for liver mass and surrounding parenchyma. ARFI values were compared between tumor types and surrounding parencyhma. RESULTS: The mean stiffness values were 2.15±0.73 m/s for hemangiomas (n=34), 3.22±0.18 m/s for FNH (n=4), 2.75±0.53 m/s for HCC (n=10) and 3.59±0.51 m/s for metastasis (n=22). Although there was not a significant difference between hemangiomas and HCC lesions in ARFI values (p>0.05), hemangiomas showed significantly different ARFI values from FNH and metastases (p<0.05). Also, there were significant differences in ARFI values between malignant and benign masses. The area under the receiver-operating characteristics curves for discriminating the malignant from benign liver masses was 0.826 (p<0.001). An ARFI value of 2.32 m/s was selected as cut-off value to differentiate malignant liver masses from benign ones (sensitivity: 0.93, specificity: 0.60). CONCLUSION: Although currently ARFI is not a definitive method for the primary diagnosis of focal solid liver lesions, it provides additional important information non-invasively for differential diagnosis.