Yonca Anik

Diffusion-Weighted Imaging in the Differential Diagnosis of Cystic Lesions of the Pancreas

OBJECTIVE The purpose of our study was to evaluate the value of diffusion-weighted imaging (DWI) in the differential diagnosis of pancreatic cysts. SUBJECTS AND METHODS Forty-two cysts (16 simple cysts, seven pseudocysts, five abscesses, three hydatid cysts, two serous cystadenomas, three mucinous cystadenomas, two mucinous cystadenocarcinomas, four cystic degenerated adenocarcinomas) were included in this prospective study. Single-shot spin-echo echo-planar DWI was performed with three b factors (0, 500, and 1,000 s/mm(2)), and apparent diffusion coefficients (ADCs) were calculated. On DWI, the signal intensity of the cysts was visually compared with the signal intensity of the pancreas parenchyma. For the quantitative evaluation, cyst-to-pancreas signal intensity ratios, ADC of the lesions, and cyst-to-pancreas ADC ratios were compared. RESULTS On visual evaluation, all cystic lesions were hyperintense on DWI with b factors of 0 and 500 s/mm(2). On DWI with a b factor of 1,000 s/mm(2), all abscesses and hydatid and neoplastic cysts were hyperintense, whereas most of the simple and pseudocysts were isointense. Quantitatively, with b factors of 0 and 500 s/mm(2), no statistical significance was achieved. With a b factor of 1,000 s/mm(2), the cyst-to-pancreas signal intensity ratios of the abscesses and hydatid and neoplastic cysts were significantly higher than those of the simple cysts and pseudocysts. Setting the cutoff value of signal intensity ratio at 1.9, the cyst-to-pancreas signal intensity ratio had a sensitivity of 70% and a specificity of 90% for differentiating abscesses, hydatid cysts, and neoplastic cysts from simple cysts and pseudocysts. The ADC and the ADC ratios of the abscesses, hydatid cysts, and neoplastic cysts were significantly lower than those of the simple cysts and pseudocysts. CONCLUSION DWI may help in the differential diagnosis of pancreatic cysts.

Diffusion-Weighted Imaging in the Differential Diagnosis of Simple and Hydatid Cysts of the Liver

OBJECTIVE The purpose of our study was to evaluate the value of diffusion-weighted imaging (DWI) in the differential diagnosis of simple and hydatid cysts of the liver, particularly in the completely liquid type of hydatid cyst. SUBJECTS AND METHODS Eighty-two cysts (43 simple cysts, 39 hydatid cysts) were included in this prospective study. DWI was performed using a breath-hold single-shot echo-planar spin-echo sequence, and apparent diffusion coefficients (ADCs) were calculated. On DW trace images, the signal intensity of cysts was visually compared with the signal intensity of the liver using a 3-point scale: 0, isointense; 1, moderately hyperintense; and 2, significantly hyperintense. Quantitatively, signal intensity of the cysts, cyst-to-liver signal intensity ratios, ADC of the cysts, and cyst-to-liver ADC ratios were compared between the groups. The statistical significance was determined using the Mann-Whitney U test. RESULTS On trace DWI (b = 1,000 s/mm2), most hydatid cysts (37/39, 95%) were hyperintense, whereas most simple cysts (40/43, 93%) were isointense with the liver. Three simple cysts (7%) were moderately hyperintense and two hydatid cysts (5%) were isointense. Quantitatively, both the signal intensity and cyst-to-liver signal intensity ratio of the hydatid cysts were significantly higher than those for simple cysts (p < 0.001). The cutoff value at 1.5 yielded a sensitivity of 77%, a specificity of 86%, and positive predictive value of 83% for the cyst-to-liver signal intensity ratio. The ADC and cyst-to-liver ADC ratio of the hydatid cysts were significantly lower than those of simple cysts (p < 0.005). For the completely liquid type in particular, we observed statistically significant differences in signal intensity, signal intensity ratio, ADC, and ADC ratios from those of simple cysts (p < 0.005). With a cutoff value of 1.5, signal intensity ratio had a sensitivity of 81%, specificity of 86%, and positive predictive value of 74%. CONCLUSION DWI may help in the differential diagnosis of hydatid and simple cysts of the liver.

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions.

PURPOSE To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. MATERIALS AND METHODS The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm(2) for DWI and b 0 and 1000 s/mm(2) for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. RESULTS Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p=0.001). The FA showed no statistical significance. With the cut-off values of ≤ 1.23 × 10(-3)mm(2)/s (b 0-1000 s/mm(2)) and ≤ 1.12 × 10(-3)mm(2)/s (b 0-1500 s/mm(2)), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤ 1.27 × 10(-3)mm(2)/s (b 1000 s/mm(2)), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm(2) and MD with a b value of 0, 1000 s/mm(2) (AUC = 0.82 ± 0.07). CONCLUSION ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision.

Magnetic Resonance Imaging of the Brain in Patients with Pseudoexfoliation Syndrome and Glaucoma

Purpose: To evaluate ischemic changes in brain magnetic resonance images in patients with pseudoexfoliation syndrome (PXS) and pseudoexfoliation glaucoma (PXG) and compare them with age- and sex-matched control subjects. Methods: This case-control study involved 16 consecutive patients with PXS, 21 patients with PXG and 18 healthy age- and sex-matched control subjects. Each subject underwent a comprehensive ophthalmological examination. In all participants, an axial T1-, T2- and proton-density-weighted and coronal cerebral 1.5-tesla magnetic resonance imaging (MRI) scan was made. White matter hyperintensities (WMH) were considered present if these were hyperintense on both proton-density- and T2-weighted images and not hypointense on T1-weighted images. White matter lesions were classified into two parts as the subcortical and periventricular regions. We used a validated rating scale of subcortical WMH: 0 = absent, 1 = punctuate foci, 2 = beginning confluence of foci and 3 = large confluent areas. Periventricular white matter lesions were classified on a scale of 0 (no white matter lesions), 1 (pencil-thin periventricular lining), 2 (thick lining) or 3 (large confluent white matter lesions). Results: The proportions of persons with WMH were 93.7% for patients with PXS, 95.2% for patients with PXG and 55.5% for control subjects. The numbers of white matter lesions in patients with PXS and PXG were significantly greater than in the control subjects (p < 0.05). White matter lesions at subcortical locations in patients with PXG were significantly more frequent than in the control subjects (80.9 vs. 33.3%; p < 0.05). The proportion of patients with subcortical WMH was 56.2% in PXS; no significant difference was found in subcortical WMH between PXS and controls. The proportions of patients with periventricular WMH were 93% in PXS, 90.4% in PXG and 44.4% in controls. White matter lesions at periventricular locations in patients with PXG and PXS were significantly more frequent than in the control subjects (p < 0.05). The difference between the pseudoexfoliation groups and controls with regard to the size of periventricular and subcortical white matter lesions was statically significant (p < 0.05). When patients with PXS were compared with PXG patients, there was no statistically significant difference in the number, size and scale of white matter lesions. Conclusion: We found a significantly higher prevalence of MRI-defined WMH in patients with a clinical diagnosis of pseudoexfoliation with or without glaucoma versus control subjects. We think that the findings in this study may shed light on a possible link between ischemic brain lesions and pseudoexfoliation, which is not related with the presence of glaucomatous optic neuropathy. Further investigations are required to resolve the underlying associations.

Apparent Diffusion Coefficient and Cerebrospinal Fluid Flow Measurements in Patients With Hydrocephalus

Objective: To evaluate the efficacy of diffusion magnetic resonance imaging and compare with cerebrospinal fluid (CSF) flow imaging in patients with hydrocephalus before and after treatment. Methods: Twenty patients with hydrocephalus (group 1, pediatric, with primary aqueductal stenosis, n = 10; group 2, adult, with normal-pressure hydrocephalus, n = 10) and 20 age-matched healthy subjects that served as controls were examined. Cerebrospinal fluid flow velocity interval was calculated as the mean absolute values of the peak craniocaudal velocity and caudocranial velocity on CSF flow measurements. On diffusion magnetic resonance imaging, apparent diffusion coefficient (ADC) values from 8 regions were evaluated. Results: The decrease in ADC values after treatment was significant in both groups (P < 0.001 for both). Preoperative mean CSF flow velocity interval value was significantly lower in group 1 and significantly higher than postoperative and control group values in group 2 (P < 0.001 for all). Conclusion: The ADC values increase in hydrocephalus and decrease significantly after treatment. Preoperative ADC value may serve as baseline, and the change in ADC may be an indicator of response to treatment and CSF flow measurements.

Positioning of infants in the neonatal intensive care unit for lumbar puncture as determined by bedside ultrasonography

Realising the paucity of data in the standardisation of the optimal position for lumbar puncture (LP) in hospitalised neonates, we have designed an observational study to measure the interspinous distance in infants in a university hospital setting. The infants were placed in two lateral recumbent and two upright positions (lateral recumbent without flexing the hips, lateral recumbent with maximal hip flexion, sitting without flexing the hips and sitting with maximal hip flexion) with concomitant heart rate (HR), transcutaneous oxygen saturation (OS) and interspinous distance (with ultrasonography) measurements. Having the patient sit with maximal hip flexion provided the largest interspinous space for the grand majority of the infants. Sitting positions with/without flexion have resulted in significant increases in HR with respect to lateral recumbent position without flexion. Although statistically significant drops in OSs have been observed between lateral recumbent and sittting with flexion, lateral recumbent with flexion and sitting without flexion, and lateral recumbent with flexion and sitting with flexion positions; no adverse hypoxic events occurred during positioning. Sitting flexed position, which seems to be sufficiently safe and serve to enhance the success rate of a LP, should be favoured for sick neonates whenever the infants condition permit a spinal tap.

Popliteus muscle sesamoid bone (cyamella): appearance on radiographs, CT and MRI

Popliteus muscle sesamoid bone, also known as cyamella, is an accessory ossicle that is located in the vicinity of the proximal musculo tendinous junction. While commonly seen in small mammals such as cats and dogs, its presence in humans is very rare. In this report, we present the radiological findings of the popliteus muscle sesamoid bone, incidentally detected in a 47-year-old male. CT and MRI features of this ossicle are described.

Comparison of gated SPECT, echocardiography and cardiac magnetic resonance imaging for the assessment of left ventricular ejection fraction and volumes

BACKGROUND Left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV) can be determined non-invasively by two-dimensional echocardiography (ECHO), gated single photon emission computed tomography (GSPECT) and cardiac magnetic resonance imaging (CMRI). This study was designed to analyze the concordance between LVEF, EDV and ESV values derived from ECHO, GSPECT and CMRI. METHODS ECHO, GSPECT and CMRI were performed in a group of 21 patients with suspected coronary artery disease. LVEF, EDV and ESV values were calculated. RESULTS The mean LVEF measured with GSPECT, ECHO and CMRI were 55.9±17.8%, 55.7±16.4% and 56.4±15.7%, respectively. The mean EDV measured with GSPECT, ECHO and CMRI were 109.2±42.4 mL, 127.5±42.2 mL and 91.1±38.0 mL, respectively. The mean ESV measured with GSPECT, ECHO and CMRI were 54.2±41.2 mL, 59.9±37.6 mL and 41.8±26.9 mL, respectively. The results of linear regression analysis showed very good correlation between LVEF and ESV values derived from GSPECT, ECHO and CMRI (r=0.91, r=0.92, r=0.97 for LVEF and r=0.86, r=0.91, r=0.91 for ESV, P<0.01). Good correlations were found between EDV values obtained from GSPECT, ECHO and CMRI (r=0.71, r=0.68, r=0.73, P<0.01). Agreement between these techniques in LVEF values was also good, but not in LV volumes, according to Bland-Altman plots. CONCLUSIONS This study showed good overall correlations between LVEF, EDV and ESV values derived from GSPECT, ECHO and CMRI. LVEF obtained from any of these three imaging modalities could be used interchangeably. However, care should be taken in comparing LV volumes.

Treatment of fixed thoracolumbar kyphosis in immature achondroplastic patient: posterior column resection combined with segmental pedicle screw fixation and posterolateral fusion

A 13-year-old male achondroplastic dwarf with fixed thoracolumbar kyphosis was treated by segmental pedicle screw fixation, posterolateral fusion combined with one stage two level posterior column resection. Preoperative and postoperative kyphosis angles were 97 and 32°, respectively. Combination of segmental pedicle instrumentation with posterior column resection is a treatment option even in immature achondroplastic patients.

Role of Interpeduncular and Prepontine Cistern Cerebrospinal Fluid Flow Measurements in Prediction of Endoscopic Third Ventriculostomy Success in Pediatric Triventricular Hydrocephalus

Aim: The aim of the present study was to evaluate the correlation of the clinical success of the endoscopic third ventriculostomy (ETV) procedure with the measurements of cerebrospinal fluid (CSF) flow through the interpeduncular and prepontine cisterns in pediatric triventricular hydrocephalus. Methods: 51 children (age range: 25–201 months; mean: 55.3 months) with primary aqueductal stenosis who have been treated with ETV were included in the study. All patients were analyzed by conventional and cine magnetic resonance imaging (MRI) before and after endoscopic treatment. Both the stroke volume and the flow velocity of CSF in the interpeduncular and prepontine cisterns were evaluated. The MRI findings were correlated with clinical outcome. Simple descriptive and independent t tests were used for statistical analyses, and receiver operating characteristic curve analysis was used for the cutoff value of the ‘flow index’ (FI). Results: Among the 51 patients, 37 patients (72.5%) responded to ETV clinically during long-term follow-up. A further analysis was made for the prediction of who would respond to ETV, using the formula (stroke volume of prepontine cistern/stroke volume of interpeduncular cistern) ×100, which was defined as the FI. Early postoperative FI values of over 40% were significantly correlated with ETV success. Conclusion: Our results suggest that ETV success can be predicted by the ratio of early CSF stroke volume values of the interpeduncular and prepontine cisterns.