Prevalence and associated risk factors of coronary artery disease in patients with a zero coronary calcium score.

PURPOSE: A zero coronary calcium score (CCS) is not able to provide a definite exclusion for coronary artery disease (CAD). The goal of this study was to determine the prevalence and associated cardiovascular risk factors of CAD in patients with zero CCS. METHODS: Six hundred thirteen patients with zero CCS referred to coronary calcium score analysis (CCSA) and coronary computed tomography angiography (CCTA) with suspicion of CAD were included. The descriptive, univariate, and multivariate analyses were used to determine the prevalence and predictors of CAD presence. RESULTS: Among 613 patients, 17 patients (2.7%) have NCCP, and obstructive CAD was found in 3 patients (0.48%). Multivariate analysis revealed that male gender and older age (≥50 years) were significantly associated with the presence of noncalcified coronary plaques (NCCP) (p < 0.05). The receiver operating characteristic (ROC) curve analysis showed that the male gender and older age (≥50 years) model had 70.6% sensitivity and 84.2% specificity for predicting NCCP. CONCLUSION: A non-negligible portion of patients with zero CCS had CAD. Male gender and older age (≥50 years) were independently associated with NCCP. Due to the high specificity value (84.2%) and negative predictive value (99.0%) of the male gender and older age (≥50 years) model, selective use of CCTA is recommended in <50 years old female patients to avoid unnecessary radiation exposure.

Evaluation of a two-image technique consisting of an axial and a coronal image generated by using the rib-flattening application: effect on reading time and diagnostic validity

Background/aim: When reading a chest CT, a radiologist needs to evaluate each rib one by one due to complex curvy shape, which makes reporting a tiresome and time-consuming task. A new curved planar reformat application that flattens ribs on a single plane may find a place in the radiology reporting room. This study aimed to evaluate the effect of a two-image set created by using the rib-flattening application on the performance of a radiologist in detecting sclerotic rib lesions in cancer patients. Materials and methods: The local Institutional Review Board approved this retrospective study. Two radiologists with different experience levels reviewed chest CT examinations of 106 patients (76 men, 30 women). We divided the patients into group A (n = 54), reviewed by a standard method, and group B (n = 52), reviewed by a standard method and the two-image set created on the rib- flattening application. Reading times, validity indices, and agreement levels with reference data were evaluated for both readers. Results: The median reading time of the junior examiner significantly decreased with the rib-flattening method (160.5 s vs. 70.0 s; P < 0.001). Diagnostic indices of the senior reader were improved significantly at per patient level (group A, AUC: 0.867; group B, AUC: 0.982; P = 0.046). The new method showed better agreement levels (kappa: 0.69 to 0.96) than the general method (kappa: 0.53 to 0.91). Conclusion: Based on improved agreement levels, reading times, and diagnostic validity indices we conclude that a two-image set consisting of an axial and a coronal flattened-rib image may be used in conjunction with an ordinary exam.

Effects of Rat Bone Marrow-Derived Mesenchymal Stem Cells and Demineralized Bone Matrix on Cranial Bone Healing.

BACKGROUND: Studies in tissue engineering about mesenchymal stem cells (MSCs) provide promising results for bone regeneration. The aim of this study was to evaluate the effects of rat bone marrow-derived MSCs (rMSCs) alone and when combined with demineralized bone matrix (DBM) on critical-sized cranial defects of rats. METHODS: Ten rats were used to obtain allogeneic rMSCs. Forty rats were separated equally into 4 groups. A full-thickness circular bone defect was created in the frontal bone of the rats. Group 1 was an operative control group. In group 2 DBM, in group 3 rMSCs, and in group 4 DBM combined with rMSCs were applied into the defects. Bone regeneration was evaluated by computed tomographic analysis and immunohistochemistry. RESULTS: In radiological evaluation, the percentage of area healed in group 3 at the 12th week was statistically significantly greater than in group 1. In group 3 and group 4, distributed healing patterns were observed more than in group 2 and in group 1. Immunohistochemical evaluation revealed that group 4 had the best osteoinductive potential. Osteoinductive potential of group 3 was similar to group 2 and was better than group 1. CONCLUSIONS: Allogeneic rMSC applications have created a statistically significant radiologic reduction of the bone defect areas at the end of the 12 weeks. The MSC applications have also increased the bone density and changed the healing patterns. Combined use of the DBM and rMSCs has created more osteoinductive responses. This combination can provide better results in craniofacial bone reconstruction.

Determination of lowest possible contrast volume in computed tomography pulmonary angiography by using pulmonary transit time.

PURPOSE: The aim of this study was to assess the effectiveness of the modified test-bolus (mTB) method in computed tomography pulmonary angiography (CTPA). MATERIALS AND METHODS: The Institutional Review Board approved this retrospective study. We reviewed 24 patients (nine men, 15 women; age range, 21-88 years) in whom CTPA was performed either by Bolus-Tracking (BT) (n = 12) or mTB (n = 12) methods. Pulmonary transit time (PTT) was used to determine scan delay time and contrast volume in the mTB group. The contrast volume, radiation dose, quantitative measures, and qualitative scores of enhancement were compared. The chi-squared test, Mann-Whitney U test, and κ statistics were used. The significance level was 0.05. RESULTS: The effective dose (P = 0.028) and contrast volume (P < 0.001) was significantly lower in the mTB group than those in the BT group. The difference in the quantitative measures and qualitative scores of enhancement between groups was statistically insignificant (P = 0.729, P = 0.635, respectively). Significantly fewer artefacts were observed in the mTB group (P = 0.024). CONCLUSION: By taking into account PTT, mTB appears to be a promising method for tailoring CTPA to the patient with the use of less contrast material and resulting in fewer artifacts.

Comparison of radiation-induced damage between CT angiography and conventional coronary angiography.

OBJECTIVE: Both computed tomography (CTA) and conventional angiography (CCA) can provide direct visualization of the coronary arteries. The aim of the present study was to compare the radiation exposure between CTA and CCA and to search whether this amount of radiation causes significant DNA damage. METHOD: Seventy-two patients who underwent CTA or CCA were enrolled prospectively. We recorded the radiation dosage that was used during the procedures and calculated the effective dose (ED). We determined the sister chromatid exchange (SCE) level from the blood samples which were drawn from the patients before and after the procedures. The change in SCE is used as the measure of DNA damage induced by the radiation. RESULTS: The patients in the CTA (n = 36) and CCA groups (n= 36) had similar baseline characteristics. The ED was higher in CTA examinations compared to CCA examinations (14.2 +/- 2.7 vs 6.4 +/- 3.1, P <0.001). The SCE level increased significantly after both angiography methods (P <0.001). When the change in SCE after angiography was compared, we did not find a significant difference among the groups (2.73 +/- 1.6 vs 2.54 +/- 1.22, P= NS). CONCLUSION: Although the patients who underwent CTA were exposed to a greater amount of radiation, the radiation-induced genetic damage was similar with both types of the procedures.

Quantitative and qualitative comparison of standard-dose and low-dose pediatric head computed tomography: a retrospective study assessing the effect of adaptive statistical iterative reconstruction.

OBJECTIVES: Our aim was to assess the effect of adaptive statistical iterative reconstruction (ASIR) on pediatric head computed tomography (CT) examinations. METHODS: We retrospectively reviewed 305 pediatric head CT examinations. The study population consisted of standard dose (STD, n = 152) examinations reconstructed with filtered back projection and low dose (LD, n = 153) examinations reconstructed with 30% (LD30) and 0% (LD0) ASIR. We compared groups by means of radiation dose, noise measures, and visual grading. Student t test, 1-way analysis of variance test, and Mann-Whitney U test were used for statistical analysis. RESULTS: The dose in the LD30 group was significantly lower (29%) than that in the STD group (P < 0.001). The noise in the white matter (P < 0.001), SNR (P < 0.001), and subjective image noise (P = 0.044) was significantly better in the STD group than those in the LD30 group. There was no significant difference between LD30 and STD groups in the sharpness (P = 0.141), diagnostic acceptability (P = 0.079), and artifacts (P = 0.750) and contrast-to-noise ratio (P = 0.718). CONCLUSIONS: In conclusion, we found that a blend of 30% ASIR in a 16-slice multidetector CT produces diagnostically acceptable pediatric head CT examinations with a 29% less dose.

Unenhanced urinary CT: value of parenchymal attenuation measurements in differentiating acute vs. chronic renal obstruction.

OBJECTIVE: We aimed to search if the renal parenchymal attenuation measurements on unenhanced CT scans could be useful in differentiating acutely obstructed kidneys from chronic cases or unobstructed kidneys. MATERIAL AND METHODS: Unenhanced CT scans of 101 patients were retrospectively reviewed. Thirty-two patients with unilateral acute renal obstruction, 34 patients with unilateral chronic renal obstruction due to various reasons and 35 control subjects were included in the study. The parenchymal densities of both kidneys were measured, from the upper poles, middle portions, and lower poles of each kidney. The mean parenchymal densities of both kidneys were calculated in all three groups of subjects. Secondary signs of renal obstruction such as perinephric stranding, size of ureteral stone, degree of hydronephrosis were also noted for each kidney. RESULTS: The mean parenchymal attenuation value on the acutely obstructed side was lower than the unobstructed side, 24.21 ± 3.68 and 30.68 ± 4.75 respectively (p<0.001). The mean parenchymal attenuation value on the acutely obstructed side (24.21 ± 3.68) was lower than both the chronically obstructed side (30.85 ± 4.53), and the control subjects (29.62 ± 3.03 on corresponding side). There was no statistically significant attenuation difference between right and left kidneys in the control group and chronic obstruction group. CONCLUSION: Renal parenchymal attenuation measurements and attenuation differences of both kidney of same patient could be useful in differentiating acute unilateral obstruction from chronic cases.

Reconstruction of cranial bone defects using Struthio camelus eggshell.

BACKGROUND: There are many synthetic materials for the treatment of bone defects, which have their own advantages and disadvantages. We aimed to compare the efficacy of ostrich eggshell, which is cheap and easily available, and demineralized bone matrix in healing of cranial bone defects. METHODS: A full-thickness circular bone defect was created in the frontal bone of 40 Wistar rats. Group 1 was the operative control group. In group 2, demineralized bone matrix applied into the defects; in group 3, Struthio camelus (ostrich) eggshell implants (OSIs) were applied into the defects; and in group 4, ostrich eggshell powders were applied into the defects. Computed tomographic analysis was performed to evaluate the healing of bone defects, the bone density, the OSI area measurements, and the OSI volume and density. At the end of the 24th week, all rats were killed. New bone formation, infection, resorption, and tissue reactions were evaluated. RESULTS: Ostrich eggshell implants were slightly resorbed, integrated with bone, stable, and supplied good cranial completeness. Ostrich eggshell powders were totally resorbed at the sixth month. There were no significant differences between control and ostrich eggshell groups in new bone formation. CONCLUSIONS: Ostrich eggshell did not seem to be an osteoproductive material, but it has some important advantages as an implant. Ostrich eggshell has a strong structure, is cheap, is shaped easily, and does not cause tissue reaction or infection. Ostrich eggshell could be a good alternative graft material for craniomaxillofacial procedures. Further studies are required to find out the potential use of the ostrich eggshell in craniomaxillofacial reconstructions.

Frontal sinus osteoma associated with pneumocephalus.

The most common causes of intracranial air are head trauma and neurosurgical procedures. Less common etiologies include infection due to gas-forming organisms, mucoceles, tumours, congenital neuroenteric cysts, and dural defects. Here, we present a case of a frontal sinus osteoma associated with longstanding pneumocephalus.

The role of late-phase pulse inversion harmonic imaging in the detection of occult hepatic metastases.

OBJECTIVE: The purpose of this study was to investigate the efficacy of late-phase pulse inversion harmonic imaging (PIHI) in detecting occult metastases and to compare the results with helical computed tomography (CT) in a group of patients whose fundamental liver sonographic results were normal. METHODS: Thirty-two patients (21 women and 11 men; age range, 20-87 years) with a known primary malignancy were enrolled in the study. The patients were evaluated with conventional sonography, unenhanced PIHI, and PIHI 3 minutes after the injection of Levovist (SH U 508A; Schering AG, Berlin, Germany). All patients also underwent triphasic helical CT within 1 week after sonography. In 1 patient, mangafodipir-enhanced magnetic resonance imaging was performed as part of the clinical workup. RESULTS: After Levovist injection, in 4 (12.5%) of 32 patients, at least 1 hypoechoic lesion was detected by PIHI; multiple lesions were shown in 1 patient. The mean diameter of newly detected lesions was 12 mm. Triphasic helical CT also showed all of the lesions that were detected by PIHI. The diagnoses were confirmed by biopsy and CT findings in 2 patients and by the typical CT and magnetic resonance imaging findings in 1 patient. For the fourth patient, the diagnosis was confirmed by follow-up and CT. Conclusions. Late-phase PIHI is comparable to helical CT for detecting occult hepatic metastases, but it protects patients from the potentially hazardous effects of radiation and iodinated contrast agents. Further series involving a larger number of patients are needed to determine its place in the evaluation of cancer staging and treatment planning.

The effects of minor hip flexion, abduction or adduction and x-ray beam angle on the radiographic joint space width of the hip.

OBJECTIVE: Joint pain may cause patients to hold their limbs in mild flexion, abduction or adduction to minimize pain, regardless of the extent of articular pathology, and these positional changes may have substantial effects on the interpretation of radiographic joint space. We aimed to study the impacts of minor degrees of flexion, abduction or adduction of the hip, as well as the angle of the x-ray beam on the radiographic joint space width (JSW) of the hip joint. METHODS: In the first part of the study, 65 patients (44 males, 21 females, mean+/-SD age 49+/-17) without clinical evidence of hip osteoarthritis (OA) who underwent intravenous pyelography (IVP) were studied. The hips were differentially positioned during the sequential radiographs required for the IVP procedure. Baseline radiographs were taken at 15 degrees internal rotation of the hips [the standard position for anteroposterior (AP) pelvis radiography]; additional positions included the hips at 15 degrees and/or 30 degrees flexion, and 15 degrees adduction and/or 30 degrees abduction. Radiographic JSWs were measured at three sites using a dial caliper: superomedial, superolateral, and the point of narrowest JSW. In the second part, 15 patients without clinical evidence of hip OA who underwent supine abdominal radiography for non-rheumatological indications were evaluated by standard (AP) pelvis x-ray in the same setting and JSW measurements were made as described above. RESULTS: When the average of the three measurements of the JSW was taken for each hip, baseline JSW was 4.38+/-0.55 mm (mean+/-SD). Positioning of the hip significantly (P<0.01) affected the radiographic JSW, with apparent widening during adduction and 30 degrees flexion, (JSW 4.56+/-0.51 mm and 4.53+/-0.58 mm, mean+/-SD), respectively, but narrowing during abduction (4.17+/-0.59 mm, mean+/-SD). Fifteen degree flexion of the hip did not result in statistically significant change in JSW measurements. Upon comparison of the AP pelvis view with the supine abdominal view, neither the average JSW nor the point of narrowest JSW differed significantly, although the superolateral JSW was significantly greater on the AP pelvis view (P=0.02). CONCLUSIONS: Subtle positional changes in the hip, such as may occur during pain or in OA, may artifactually alter the measured radiographic JSW. Thus, longitudinal studies which employ hip JSW to assess disease progression may yield biased results due to changes in pain rather than structure unless care is taken to ensure constant positioning of the hip.

Evaluation of the normal appendix at low-dose non-enhanced spiral CT.

PURPOSE: To evaluate the frequency of visualization, thickness and location of the normal appendix at non-enhanced spiral computed tomography (CT). MATERIALS AND METHODS: Low-dose spiral CT scans obtained for renal colic assessment in 243 patients were retrospectively reviewed. The frequency of visualization, thickness and location of normal appendices were recorded without knowledge of the patients' history for the appendectomy. RESULTS: Forty of 234 patients had a past history of appendectomy (17%). Sensitivity, specificity, positive and negative predictive values, and accuracy of visualization of the normal appendix were 71%, 85%, 96%, 37% and 73%, respectively. When no intraluminal content was visualized, this area was excluded from the measurement and the mean thickness was 3.4 mm+/-0.66. CONCLUSION: The normal appendix is frequently seen at nonenhanced spiral CT. Knowing the normal thickness of the appendix can help reduce false positive and false negative diagnoses of acute appendicitis when reviewing non-enhanced spiral CT.

Distinguishing pelvic phleboliths from distal ureteral calculi: thin-slice CT findings.

The objective is to evaluate the appearance of phleboliths and distal ureteral stones by determining their roundness and presence of central lucency on thin-slice CT. Seventy-seven patients with pelvic radioopacities at unenhanced CT were selected. Those patients consequently underwent thin-slice CT with 1-mm collimation, a FOV of 10 cm, a pitch of 1:1 and a bone reconstruction algorithm. Three radiologists reviewed all images for roundness and the presence of central radiolucency. No calculi showed central lucency on either imaging technique used. Thin-slice CT revealed central lucency in 60% of phleboliths with 100% specificity. Three of 40 ureteral stones showed round contour. Thin-slice CT revealed a round contour in 97% of phleboliths with 93% specificity. Central lucency is a characteristic finding of pelvic phleboliths on thin-slice CT. This finding can therefore be used in combination with roundness as a problem-solving tool in differentiating phleboliths from distal ureteral stones.

Characterization of hyperechoic focal liver lesions: quantitative evaluation with pulse inversion harmonic imaging in the late phase of levovist.

OBJECTIVE: The aim of this study was to evaluate hyperechoic focal liver lesions with pulse inversion harmonic imaging in the late phase of SH U 508A (Levovist; Schering AG, Berlin, Germany) and to determine whether quantitative evaluation improves the characterization of the lesions. METHODS: Twenty-six patients with hyperechoic liver lesions were enrolled in this study. Pulse inversion harmonic imaging was performed before and after administration of Levovist. Scan data were digitally stored, and each lesion was analyzed with a personal computer-based quantification package. All lesions were confirmed by histologic or triphasic spiral computed tomographic examinations. The intensity was measured in decibels in regions of interest drawn within the lesion and surrounding liver parenchyma. The lesion-liver ratios were than calculated. After contrast agent administration, a ratio equal to or greater than 1 was presumed benign, whereas a ratio of less than 1 was considered malignant. RESULTS: Nine malignant (7 metastases, 1 hepatocellular carcinoma, and 1 cholangiocarcinoma) and 17 benign (14 hemangioma, 1 focal nodular hyperplasia, 1 focal fatty change, and 1 inflammatory pseudotumor) hyperechoic lesions were quantitatively evaluated. All malignant (n = 9) and 2 benign lesions (1 hemangioma and 1 inflammatory pseudotumor) had ratios of less than 1. In 15 of 17 benign lesions, the ratios were equal to or greater than 1. The intensity ratios calculated for benign and malignant lesions showed a statistically significant difference (P < .05). CONCLUSIONS: Pulse inversion harmonic imaging with quantitative evaluation facilitates the differential diagnosis of hyperechoic focal liver lesions. A lesion-liver ratio equal to or greater than 1 predicts a benign nature, assuming that malignant lesions show a ratio of less than 1.

[Case report: Complex composite odontoma: Plain radiography and computed tomography findings]. / Kompleks kompozit odontoma: düz radyografi ve BT bulgulari.

Complex composite odontoma is a rare benign odontogenic hamartoma seen in association with a primary tooth. Although it is seen most frequently between 10-19 years of age, here we present a lesion of unusual size in the mandible of a 6-year-old boy and report its clinical, radiographic, CT and histologic findings. Also, we discuss the value of three dimensional images.

[Assessment of mandibular vascular canals by dental CT]. / Mandibulanin lingual vasküler kanallarinin dental BT ile degerlendirilmesi.

PURPOSE: Sublingual artery and its branches run in the floor of the mouth and prone to substantial bleeding when injured during an implantation procedure. These branches enter the mandible from the lingual side and run through bony canals in the mandible. The purpose of this investigation is to evaluate the frequency, diameter, direction and position of lingual canals by dental CT. MATERIALS AND METHODS: 26 patients who underwent dental CT of the mandible before implantation were included in this study. Tomographic examination was performed in a transverse plane parallel to the mandibular base by bone algorithm. Multiplanar reconstructions were obtained in the sagittal and coronal oblique planes. RESULTS: All patients demonstrated at least one canal, and 8 patients had two or more canals. Two of the patients presented with four canals. The typical lingual canal locations were the middle of the mandible and the premolar regions. The mean diameter of the lingual canals was 0.8 mm +/- 0.2 mm in the middle, 0.6 mm +/- 0.1 mm in the premolar regions. The direction of median canal was anterior and slightly caudal. Lateral canals were directed in a medial manner. CONCLUSION: Before the dental implantation procedure, beside the relationships of implant with the important anatomic structures, lingual vascular canals should also be evaluated. Dental CT examination easily demonstrates the presence, position, direction and size of the lingual canals. By ensuring that radiologists and dentists are aware of these canals and their importance, bleeding complications during the placement of implants could be avoided.

Lung at thin-section CT: influence of multiple-segment reconstruction on image quality.

PURPOSE: To evaluate multiple-segment reconstruction to reduce cardiac-motion artifacts on thin-section computed tomographic (CT) images in the lung. MATERIALS AND METHODS: Fifty patients were enrolled in the study. All images were obtained with a scanner capable of 1-second revolution time. Routine lung thin-section CT examination was performed with images reconstructed with bone algorithm. Multiple-segment images reconstructed with lung algorithm were obtained for three levels in the left paracardiac region. Segment images were reconstructed retrospectively with data for 225 degrees rotation rather than the 360 degrees rotation used for a complete scan. To minimize differences resulting from reconstruction algorithms, additional nonsegmented reconstruction was performed with lung algorithm. Three radiologists reviewed each set of images and assigned a quality score. Multiway analysis of variance was performed to compare motion artifact reduction with 225 degrees and 360 degrees reconstructions. RESULTS: Differences were not significant (P >.05) between scores for images reconstructed with bone or lung algorithms. Differences were significant between scores for reconstructed images obtained with the combination of 360 degrees bone and 225 degrees segment algorithms (P <.001) and for those obtained with the combination of 360 degrees lung and 225 degrees segment algorithms (P <.001). CONCLUSION: Multiple-segment reconstruction of lung thin-section CT images is an effective technique for reducing cardiac-motion artifacts without increasing patient dose.

Clinical approach to graft hepatic artery thrombosis following living related liver transplantation.

Hepatic artery thrombosis (HAT) has an occurrence rate of 1.7-26% following living donor liver transplantation (LDLT) and is one of the most common reasons for graft loss and mortality in this population. There is a higher incidence of HAT in pediatric recipients. The aim of this case report is to discuss clinical approaches for the treatment of HAT occurring in the early post-operative period after LDLT. An 11-month-old, 7.8-kg female with cirrhosis secondary to biliary atresia underwent LDLT at Gazi University Hospital in Ankara. The graft was a left lateral segment from her father with a left hepatic artery (HA) of 2 mm diameter and a graft weight/recipient body weight ratio of 2.0%. After an uneventful early post-operative period, HAT was diagnosed by Doppler ultrasonography (USG) on the fifth post-operative day. Following angiographic evaluation, immediate exploration and reanastomosis was performed using an operation microscope. Post-operatively, the HA was patented by Doppler USG and graft function returned to normal. Now, 42 months later, the patient continues to do well with normal graft function, using a regimen of tacrolimus monotherapy for immunosuppression. In countries which have very limited resources for urgent re-transplantation, given their serious donor shortage, graft salvage may be the only option for patient survival when HAT occurs. In these circumstances, early diagnosis and immediate revascularization may be the only method for graft salvage. A daily routine of Doppler USG examination in the early post-operative period may provide a method for the early diagnosis of HAT, before liver enzymes are elevated and hepatic necrosis has begun.

Detection and differential diagnosis of hepatic masses using pulse inversion harmonic imaging during the liver-specific late phase of contrast enhancement with Levovist.

PURPOSE: The purpose of this study was to investigate whether late-phase pulse inversion harmonic imaging (PIHI) increases conspicuity in hepatic masses, helps to differentiate benign from malignant lesions, and demonstrates a greater number of and smaller metastatic lesions than do conventional (fundamental) sonography and helical CT. METHODS: Thirty patients (17 women and 13 men; age range, 35-77 years; mean age, 54 years) with known or suspected liver masses were evaluated using both fundamental sonography and contrast-enhanced PIHI during the liver-specific late phase of Levovist. The patients also underwent contrast-enhanced triphasic helical CT examinations within 1 week after sonography. In 4 of the patients, gadolinium-enhanced MRI was also performed as a part of their clinical work-up. RESULTS: The increase in the lesions' conspicuity on PIHI compared with fundamental sonography was significantly greater in malignant lesions than in benign lesions (p< 0.001). An echogenic rim was observed on PIHI in 8 (53%) of 15 malignant lesions. The mean number of metastatic lesions visualized on PIHI (5.5 +/- 5.3) was significantly higher than the mean number visualized on fundamental sonography (2.5 +/- 2.1, p < 0.05). Although lesions as small as 3 mm were observed on PIHI, the mean sizes of the smallest lesions demonstrated using fundamental sonography, PIHI, and helical CT were not significantly different. CONCLUSIONS: Late-phase PIHI is a useful technique for characterizing hepatic lesions and demonstrating both a greater number of and smaller metastases. It may help to differentiate benign from malignant liver masses and may obviate unnecessary and expensive further imaging.