Iodine removal in intravenous dual-energy CT-cholangiography: Is virtual non-enhanced imaging effective to replace true non-enhanced imaging?

Purpose

To evaluate whether virtual non-enhanced imaging (VNI) is effective to replace true non-enhanced imaging (TNI) applying iodine removal in intravenous dual-energy CT-cholangiography.

Materials and Methods

From April 2009 until February 2010, fifteen potential donors for living-related liver transplantation (mean age 37.6 ± 10.8 years) were included. Potential donors underwent a two-phase CT-examination of the liver. The first phase consisted of a single-energy non-enhanced CT-acquisition that provided TNI. After administration of hepatobiliary contrast agent, the second phase was performed as a dual-energy cholangiographic CT-acquisition. This provided VNI. Objective image quality (attenuation values [bile ducts and liver parenchyma] and contrast-to-noise ratio) and subjective overall image quality (1 – excellent; 5 – non diagnostic) were evaluated. Effective radiation dose was compared.

Results

For TNI and VNI, attenuation values for bile ducts were 16.8 ± 11.2 HU and 5.5 ± 17.0 HU (p < 0.05) and for liver parenchyma 55.3 ± 8.4 HU and 58.1 ± 10.6 HU (n.s.). For TNI and VNI, contrast-to-noise ratio was 2.6 ± 0.6 HU and 6.9 ± 2.1 HU (p < 0.001). For VNI, subjective overall image quality was 1 in ten datasets, 2 in four datasets and 3 in one dataset. Effective radiation dose for the dual-energy cholangiographic CT-acquisition was 3.6 ± 0.9mSv and for two-phase single-energy CT-cholangiography 5.1 ± 1.3mSv (p < 0.001).

Conclusion

In this study on iodine removal in intravenous dual-energy CT-cholangiography, subjective image quality is equivalent, contrast-to-noise ratio is improved and effective radiation dose is reduced when VNI is performed. The differences between TNI and VNI with respect to attenuation values seem to have limited clinical relevance and therefore we consider VNI as effective to replace TNI.     

Shape and volume of internal anal sphincter showed by three-dimensional anorectal ultrasonography

Purpose

The aim of this work is to characterize the shape and the volume of the internal anal sphincter (IAS) in normal subjects by three-dimensional anorectal ultrasonography.

Methods

Thirty-nine normal volunteer males (mean age 58.5 ± 18.7) and 25 females (mean age 59.4 ± 14.1) were submitted to anorectal ultrasonography.The tissue is defined by a semiautomatic procedure. Measurements of thickness, length and volume were assessed automatically.The software provides an average number of 57,600 thickness measurements, 360 length measurements for each zone (90 for each quadrant) and seven volume measurements (one for each anatomical area).The mean values of magnitudes were calculated for the entire volume in each quadrant and zone. Age and gender-related variations were analyzed.

Results

In assessments of the whole tissue, only thickness was gender-related, with greater thickness for females (male thickness: 1.81 ± 0.47 mm, female thickness 2.16 ± 0.57 mm, P-value < 0.01).In the distal zone: thickness, length and volume were all larger in females (for male and female respectively: 1.83 ± 0.49 mm vs 2.34 ± 0.58 mm, P-value < 0.01, for the thickness; 10.87 ± 2.10 mm vs 12.18 ± 2.21 mm, P-value < 0.02 for the length and 1501 ± 605 mm³ vs 2169 ± 871 mm³, P-value < 0.01 for the volume). In the medial zone, only thickness was gender-related, with greater thickness in females (male thickness: 2.04 ± 0.60 mm, female thickness:2.44 ± 0.74 mm, P-value < 0.02).The only variation observed in the proximal zone concerned length, larger in males (respectively: 11.27 ± 2.84 mm vs 9.55 ± 2.43 mm, P-value < 0.02).The male population was significantly positively correlated with ageing for volume in the whole tissue (ρ = 0.32, P-value < 0.05), and for both thickness and volume in the medial zone (ρ = 0.33, P-value < 0.05 for thickness; ρ = 0.39, P-value < 0.02 for the volume).

Conclusion

This new method is useful to understand both functional anal disorders and local damage which may affect only part of the muscle tissue.     

Dual-energy, standard and low-kVp contrast-enhanced CT-cholangiography: a comparative analysis of image quality and radiation exposure

Objective

Quantitative image quality assessment in terms of image noise (IN), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) in relation to required radiation dose (RD) for dual-energy (DE), standard and low-kVp contrast-enhanced computed-tomography (CT) cholangiography.

Materials and methods

For each of 22 DECT-cholangiography examinations, 3 image datasets were analyzed as independent single-source CT-acquisitions at different tube potential, i.e. 80 kVp, 120 kVp-equivalent (linear blended dataset M0.3: 30% 80 kVp, 70% 140 kVp), and 140 kVp. Analysis comprised determination of IN, CNR and SNR in regions of interest (ROI) placed in liver parenchyma and contrasted bile ducts. IN was evaluated as mean standard deviation of 3 ROI placed within liver parenchyma (segments 6/7, 5/8, 2/3); CNR was assessed as bile duct-to-liver parenchyma ratio, and SNR as bile duct-to-image noise ratio. RD in terms of CT dose index (CTDI_vol), dose-length product (DLP) and effective dose (ED) has been determined for each of the datasets, and compared to console prediction and scan summary values. Using phantom measurements of CTDI_vol, a method for separating comprehensive RD values of DE-acquisitions into the original RD contribution of each tube (80 kVp/140 kVp) has been developed, enabling comparison of all 3 datasets as if independently acquired using single-source “single-energy” technique.

Results

Highest IN was detected for 80 kVp- (38.6 ± 5.1 HU), lowest for 120 kVp-equivalent linear blended M0.3-datasets (23.1 ± 3.4 HU) with significant differences between all datasets (P < 0.001). Highest SNR and CNR were measured for M0.3- (SNR: 14.8 ± 4.1; CNR: 11.6 ± 3.8) and 80 kVp-datasets (SNR: 13.8 ± 4.8; CNR: 11.2 ± 4.5); lowest for 140 kVp-datasets (SNR: 9.5 ± 2.5; CNR: 7.1 ± 2.3) with significant differences between M0.3- and 140 kVp-datasets as well as between 80 kVp- and 140kVp-datasets (both P < 0.001 for both CNR, SNR). CTDI_vol, DLP and ED were reduced by 50% for low-kilovoltage acquisitions (CTDI_vol: 5.5 ± 1.4 mGy; DLP: 127.8 ± 40.1 mGy cm; ED: 1.9 ± 0.6 mSv) compared to comprehensive DE-acquisitions (CTDI_vol: 11.0 ± 2.3 mGy; DLP: 253.8 ± 67.5 mGy cm; ED: 3.8 ± 1.0 mSv, tube contribution: 80 kVp: 44.5%; 140 kVp: 55.5%), and by 20% compared to conventional acquisitions at 120 kVp (CTDI_vol: 6.71 mGy; DLP: 153.5 ± 16.9 mGy cm; ED: 2.3 ± 0.3 mSv).

Conclusions

Despite higher IN, low-kilovoltage CT-cholangiography reveals no significant difference with respect to CNR and SNR when compared to linear blended images yielded by DECT. Compared to DECT or conventional CT at 120 kVp, contrast-enhanced low-kVp CT cholangiography potentially allows reduction of patient dose by up to 50% or 20%, respectively. Therefore, CT-cholangiography at 80 kVp should be considered as an alternative to DECT-cholangiography whenever DECT is unavailable, or if increased image quality of DECT regarding quantitative bile duct evaluation is not needed for diagnosis.     

CT angiography of various superficial femoral artery stents: an in vitro phantom study

Purpose

To evaluate CT reconstruction parameters to improve stent lumen visualization in vitro.

Material and methods

12 latest superficial femoral artery (SFA) stents were placed in a vessel phantom (diameter 4.7 mm, intravascular attenuation 250 HU, extravascular density 50 HU). Stents were imaged with a 128-slice scanner (SOMATOM Definition Flash, Siemens, Germany) with standard parameters: 120 kV, 200 mAs, collimation 128 mm × 0.6 mm. Different reconstruction parameters were evaluated: B26f, B30f, B45f, B46f and B60f kernel; slice thickness of 0.6, 2.0 and 5.0 mm. To measure visualization characteristics, stent lumen diameter and intraluminal attenuation were assessed.

Results

Best stent lumen visualization could be obtained using the B46f kernel (p < 0.001). The visible stent lumen ranged from 66.4% to 83.3% with a mean diameter of 77.7 ± 4.6%. Nitinol stents showed a significant improved lumen visibility compared to the cobalt–chromium stent (p = 0.02). The most realistic lumen attenuation was achieved using the B46f kernel with a mean attenuation of 259.3 ± 8.9 HU. The visible lumen diameter in protocols with 5 mm slice thickness was significantly lower (70.0 ± 4.9%) compared to thinner slices (p < 0.001).

Conclusion

CTA of SFA stents should be reconstructed with a slice thickness of 2.0 mm and a B46f kernel to achieve best image quality and to become more sensitive to exclude instent restenosis.     

Super-micro-bland particle embolization combined with RF-ablation: angiographic, macroscopic and microscopic features in porcine kidneys

Purpose

To describe angiographic, macroscopic and microscopic features of super-micro-bland particle embolization in combination with RF-ablation in kidneys. Thereby, a special focus was given on the impact of the sequence of the different procedural steps.

Materials and methods

In ten pigs, super-micro-bland particle embolization combined with RF-ablation was carried out. Super-micro-bland embolization was performed with spherical particles of very small size and tight calibration (40 ± 10 μm). In the left kidneys, RF-ablations were performed before embolization (I). In the right kidneys, RF-ablations were performed after embolization (II). The animals were killed three hours after the procedures. Angiographic (e.g. vessel architecture), macroscopic (e.g. long and short axes of the RF-ablations) and microscopic (e.g. particle distribution) study goals were defined.

Results

Angiography detected almost no vessels in the center of the RF-ablations in I. In II, angiography could not define the RF-ablations. Macroscopy detected significantly larger long and short axes of the RF-ablations in II compared to I (52.2 ± 3.2 mm vs. 45.3 ± 6.9 mm [P < 0.05] and 25.1 ± 3.5 mm vs. 20.0 ± 1.9 mm [P < 0.01], respectively). Microscopy detected irregular particle distribution at the rim of the RF-ablations in I. In II, microscopy detected homogeneous particle distribution at the rim of the RF-ablations. Microscopy detected no particles in the center of the RF-ablations in I and II.

Conclusion

The sequence of the different procedural steps of super-micro-bland particle embolization combined with RF-ablation impacts angiographic, macroscopic and microscopic features in kidneys in the acute setting.     

Diagnostic value of the delayed phase image for iso-attenuating pancreatic carcinomas in the pancreatic parenchymal phase on multidetector computed tomography

Purpose

To assess the value of the delayed phase (DP) in pancreatic carcinomas which appear iso-attenuating in the pancreatic parenchymal phase (PPP).

Materials and methods

Fifty-seven preoperative MDCT studies of pancreatic carcinomas were retrospectively reviewed. The size of the tumors, and the Hounsfield unit (HU) of the tumors and pancreatic parenchyma were measured. The tumor-to-pancreas contrast (TPC: |HU [tumor] − HU [normal pancreas]|) was calculated.

Results

Eight cases (14.0%) showed iso-attenuation and 49 showed hypo-attenuation in the PPP. The DP images revealed seven of eight (87.5%) iso-attenuating tumors to be hyper-attenuating. The size of iso-attenuating tumors was smaller than that of hypo-attenuating tumors (mean ± S.D.: 12.4 ± 4.8 mm vs. 30.3 ± 9.0 mm, p < 0.0001). In hypo-attenuating tumors, TPC in the PPP (60.2 ± 24.6 HU) was higher than those in the portal venous phase (PVP, 40.5 ± 23.0 HU, p < 0.0001) and DP (18.3 ± 11.8 HU, p < 0.0001). In contrast, in iso-attenuating tumors, TPC in the DP (26.0 ± 4.9 HU) was higher than those in the PPP (9.2 ± 3.7 HU, p = 0.0003) and PVP (7.1 ± 4.7 HU, p = 0.001) phases.

Conclusion

The DP image is helpful in depicting small iso-attenuating pancreatic carcinomas as slightly hyper-attenuating tumors.     

Evaluation of contrast medium enhancement and [(18)F]-FDG uptake of liver metastasis in PET/CT prior to therapy

Objective

To evaluate the contrast medium enhancement and [¹⁸F]-FDG uptake of liver metastases in patients suffering from colon or breast carcinoma prior to therapy.

Material and methods

PET/CT (Philips Gemini) with 200 MBq [¹⁸F]-FDG and contrast medium was performed in 50 patients with colon and 39 patients with breast carcinoma. Lesions were characterized with the presence or the absence of a rim enhancement. The area size, the HU_mean, HU_max, SUV_mean, SUV_max of the lesion and of the liver were determined. The standard uptake values (SUVs) were correlated with the tumor markers CEA and CA 15-3.

Results

The lesions of colon carcinoma had HU_mean-values of 70.7 ± 19.2 and of breast carcinoma 88.1 ± 21.7 (p < 0.0001). In breast cancer the SUV_mean was 3.9 ± 1.3 versus 4.4 ± 1.9 in colon carcinoma (p = 0.0182). Lesion of colon carcinoma with rim enhancement had a significantly higher SUV_mean (4.4 ± 1.5 versus 3.6 ± 1.2; p = 0.001) and SUV_max (6.7 ± 2.6 versus 5.1 ± 2.1; p = 0.000) than lesions without a rim enhancement. A good correlation between tumor markers and SUVs_max could be found in both tumor groups; r = 0.83 (p < 0.01) for colon carcinoma and r = 0.82 (p < 0.01) for breast carcinoma.

Conclusions

The rim enhancement of the lesions in colon carcinoma indicate a significantly higher SUV.     

How accurate are measurements of skin-lesion depths on prebiopsy supine chest computed tomography for transthoracic needle biopsies?

Aim

To evaluate the accuracy of depth measurements on supine chest computed tomography (CT) for transthoracic needle biopsy (TNB).

Materials and methods

We measured skin-lesion depths from the skin surface to nodules on both prebiopsy supine CT scans and CT scans obtained during cone beam CT-guided TNB in the supine (n = 29) or prone (n = 40) position in 69 patients, and analyzed the differences between the two measurements, based on patient position for the biopsy and lesion location.

Results

Skin-lesion depths measured on prebiopsy supine CT scans were significantly larger than those measured on CT scans obtained during TNB in the prone position (p < 0.001; mean difference ± standard deviation (SD), 6.2 ± 5.7 mm; range, 0–18 mm), but the differences showed marginal significance in the supine position (p = 0.051; 3.5 ± 3.9 mm; 0–13 mm). Additionally, the differences were significantly larger for the upper (mean ± SD, 7.8 ± 5.7 mm) and middle (10.1 ± 6.5 mm) lung zones than for the lower lung zones (3.1 ± 3.3 mm) in the prone position (p = 0.011), and were larger for the upper lung zone (4.6 ± 5.0 mm) than for the middle (2.4 ± 2.0 mm) and lower (2.3 ± 2.3 mm) lung zones in the supine position (p = 0.004).

Conclusions

Skin-lesion depths measured on prebiopsy supine chest CT scans were inaccurate for TNB in the prone position, particularly for nodules in the upper and middle lung zones.     

IVIM-DWI of transplanted kidneys: Reduced diffusion and perfusion dependent on cold ischemia time

Purpose

To evaluate the effect of cold ischemia time (CIT) of renal allografts on diffusion and perfusion using intravoxel incoherent motion (IVIM) derived parameters.

Material and methods

A total of 37 patients with renal allografts (CIT: 27 <15 h, 10 ≥15 h) and 30 individuals with healthy kidneys were examined at 1.5 T using a single-shot echo-planar diffusion-weighted pulse sequence with nine b-values ranging from 0 to 800 s/mm². ADC, perfusion fraction f, and the diffusion coefficient D were calculated using the IVIM model. Parameters of allografts stratified by CIT were compared with healthy kidney groups using the Mann–Whitney U test for unpaired data. We computed the Spearman correlation coefficient for correlation with creatinine values.

Results

ADC, D, and f of transplanted kidneys were significantly lower than in the healthy controls. The long-CIT group showed significantly lower diffusion parameters compared with the short-CIT group [mean ± SD]: ADC: 1.63 ± 0.14 μm²/ms, f: 11.90 ± 5.22%, D: 1.55 ± 0.25 μm²/ms versus ADC: 1.79 ± 0.13 μm²/ms, f: 16.12  ± 3.43%, D: 1.73 ± 0.14 μm²/ms, P_ADC, _f, _D < 0.05.

Conclusion

Our results suggest that diffusion parameters, especially the ADC, depend on the CIT of the kidney allograft. Potentially, this stands for functional changes in renal allografts. Diffusion-weighted imaging could be used for follow-up examinations. Thus, diffusion parameters may help guide therapy in patients with delayed graft function.     

Comparison of the aortic valve calcium content in the bicuspid and tricuspid stenotic aortic valve using non-enhanced 64-detector-row-computed tomography with prospective ECG-triggering

Purpose

The aim of our study was to compare the calcium content measured by non-enhanced multidetector-row-computed tomography (MDCT) between patients with significant stenosis of bicuspid (BAV) and tricuspid aortic valve (TAV). Another aim of our study was to assess the accuracy of the non-enhanced MDCT to distinguish BAV and TAV based on the calcified plaque morphology, and to compare the results with the transesophageal echocardiography.

Subjects and methods

A retrospective analysis of prospectively collected data was performed. Consecutive patients with symptomatic aortic stenosis (AS) admitted to hospital for evaluation before valve surgery underwent clinical evaluation, transthoracic and transesophageal echocardiography, and non-enhanced examination with the 64-detector-row CT using prospective ECG triggering with data acquisition in diastolic phase. The data acquisition started at 55% of the R–R interval. The patients were examined in the supine position in mild inspiration. Data were evaluated using dedicated software for calcium scoring, the volume of calcifications and calcium content were obtained.

Results

Thirty-seven patients (20 males, age 48–83 years) were enrolled. BAV was present in 13 patients, TAV in 24 patients. The calcium score in patients with severe AS (mean gradient >50 mmHg) was higher than in those with moderate AS (1123 ± 616 mg versus 634 ± 475, P = 0.011). Significant correlation between the calcium scores and transaortic gradients was found (r = 0.53, P = 0.002). The patients with BAV did not differ significantly from those with TAV in the AS severity (58 ± 13 versus 53 ± 20 mmHg), nor in the valve calcium score (1168 ± 717 versus 795 ± 530 mg, P = 0.093). The overall sensitivity to detect BAV in patients with calcified severe AS was 0.923 (12/13) and specificity 0.958 (23/24). The overall accuracy was 0.945 (35/37).

Conclusion

We observed higher calcium score in patients with severe AS than with moderate AS. However, no difference in aortic valve calcium score between BAV and TAV was found. Thus, in our sample, the aortic valve calcium score correlated with AS severity, not with aortic valve morphology. Based on the calcified plaque space relationship, the aortic BAV and TAV could be distinguished in most cases.     

Dual energy CT monitoring of the renal corticomedullary sodium gradient in swine

Objective

To evaluate the feasibility of dual-energy CT (DECT) for monitoring dynamic changes in the renal corticomedullary sodium gradient in swine.

Material and methods

This study was approved by our Institutional Animal Care and Use Committee. Four water-restricted pigs were CT-scanned at 80 and 140 kVp at baseline and at 5 min intervals for 30 min during saline or furosemide diuresis. The renal cortical and medullary CT numbers were recorded. A DECT basis material decomposition method was used to quantify renal cortical and medullary sodium concentrations and medulla-to-cortex sodium ratios at each time point based on the measured CT numbers. The sodium concentrations and medulla-to-cortex sodium ratios were compared between baseline and at 30 min diuresis using paired Student t-tests. The medulla-to-cortex sodium ratios were considered to reflect the corticomedullary sodium gradient.

Results

At baseline prior to saline diuresis, the mean medullary and cortical sodium concentrations were 103.8 ± 8.7 and 65.3 ± 1.7 mmol/l, respectively, corresponding to a medulla-to-cortex sodium ratio of 1.59. At 30 min of saline diuresis, the medullary and cortical sodium concentrations decreased to 72.3 ± 1.0 and 56.0 ± 1.4 mmol/l, respectively, corresponding to a significantly reduced medulla-to-cortex sodium ratio of 1.29 (P < 0.05). At baseline prior to furosemide diuresis, the mean medullary and cortical sodium concentrations were 110.5 ± 3.6 and 66.7 ± 4.1 mmol/l, respectively, corresponding to a medulla-to-cortex sodium ratio of 1.66. At 30 min of furosemide diuresis, the medullary and cortical sodium concentrations decreased to 68.5 ± 0.3 and 58.9 ± 4.0 mmol/l, respectively, corresponding to a significantly reduced medulla-to-cortex sodium ratio of 1.16 (P < 0.05). One of the 4 pigs developed acute tubular necrosis likely related to prolonged hypoxia during intubation prior to the furosemide diuresis experiment. The medulla-to-cortex sodium ratio for this pig, which was excluded from the mean medulla-to-cortex ratio above, was 1.07 at baseline and 1.15 at 30 min following the administration of furosemide.

Conclusion

DECT monitoring of dynamic changes in the renal corticomedullary sodium gradient after physiologic challenges is feasible in swine.     

A preliminary study of apparent diffusion coefficient in chemotherapy-induced liver damage

Objectives

To investigate changes in the hepatic apparent diffusion coefficient (ADC) in patients undergoing chemotherapy.

Methods

We enrolled 54 patients (25 women; mean age 57.0 ± 13.1 years, range 29–89 years) undergoing chemotherapy for tumor and 10 controls (7 women; mean age 55.1 ± 17.5 years, range 23–81 years). The patients were tested for serum alanine aminotransferase (ALT) activity (abnormal, normal) and fatty liver. Hepatic ADC values were compared among controls, patients and subgroups. Pearson correlation coefficient was used to assess the correlation between ADC and ALT activity.

Results

Hepatic ADC0,850 (×10⁻³ mm²/s) was lower for patients than controls (1.14 ± 0.18 vs. 1.28 ± 0.12, P = 0.02) and was lower for patients with than without fatty liver and controls (1.01 ± 0.06 vs. 1.18 ± 0.18 and 1.28 ± 0.12, respectively, all P < 0.01), with no significant difference between patients without fatty liver and controls (P = 0.07). ADC0,850 was lower for patients with abnormal ALT than normal ALT activity and controls (0.99 ± 0.06 vs. 1.17 ± 0.18 and 1.28 ± 0.12, respectively, all P < 0.05), with a significant difference also being seen between patients with normal ALT activity and controls (P = 0.04). Hepatic ADC0,850 was not correlated with ALT activity in patients (r = -0.24, P = 0.08).

Conclusions

Although ADC did not correlate with ALT values, it did distinguish patient likely to have chemotherapy-induced liver damage as indicated by abnormal ALT values or fatty liver. These mechanisms need to be disentangled.     

Ultrasonographic differentiation between Kikuchi's disease and lymphoma in patients with cervical lymphadenopathy

Purpose

Kikuchi's disease, or histiocytic necrotizing lymphadenitis, is a self-limited necrotizing lymphadenitis. Clinically, it resembles lymphoma. We want to compare the sonographic features between Kikuchi's disease and lymphoma in patients with cervical lymphadenopathy.

Materials and methods

The study protocol was approved by the institutional review board. Two hundred and twenty six cervical lymph nodes (137 nodes from 21 Kikuchi's disease patients and 89 nodes from 20 malignant lymphoma patients) were examined. The demographic and ultrasonographic characteristics of lymph nodes were collected and analyzed.

Results

The Kikuchi's disease patients (mean age, 24.2 years; range, 8–57 years) were younger than those with lymphoma (mean age, 54 years; range, 13–81 years). There was no difference in laterality of nodes (p = 0.19). The nodal distribution demonstrated most enlarged neck lymph nodes located at level II, III and V. The ranges of short-axis and long-axis length were 6.5 ± 2.3 mm (mean ± SD) versus 13.4 ± 5.1 mm and 13.4 ± 5.0 mm versus 21.2 ± 9.2 mm for Kikuchi's disease versus lymphoma (p < 0.01), respectively. The S/R ratio of Kikuchi's disease nodes was 0.5 ± 0.2 compared to 0.7 ± 0.2 in lymphoma nodes (p < 0.01). Eighty-seven of 137 nodes (63.5%) of Kikuchi's disease, and eight of 89 nodes (9%) of malignant lymphoma had signs of cortical widening (p < 0.01). Seventy-six nodes (55.5%) of Kikuchi's disease and twenty-eight nodes (31.5%) of malignant lymphoma were matted (p < 0.01). Forty-five of 89 nodes among lymphoma and twenty-four among 137 of Kikuchi's disease had features of micronodular reticular echotexture (p < 0.01). All nodes exhibited hypoechogenicity except one lymphomatous node demonstrated isoechogenicity, and there was no difference in sharpness of border and presence of echogenic hilum between the two diseases (p > 0.05).

Conclusion

Analysis of basic ultrasonographic characteristics (size, shape, rims, matting and echotexture) helps differentiate cervical lymph nodes in patients with Kikuchi's disease and lymphoma. Cervical lymphadenopathies in patients with Kikuchi's disease have smaller size, less round, less micronodular reticular echotexture, and more signs of matting and cortical widening than those with lymphoma examined under ultrasound.     

Atypical myocardial delayed enhancement after surgical ventricle restoration

Objective

To retrospectively evaluate delayed enhancement after surgical ventricle restoration (SVR).

Materials and methods

Thirty patients with post-ischemic akinetic dilatation underwent cine and gadobenate dimeglumine-enhanced MRI before and 2–6 months after SVR. End-diastolic volume (EDV) normalized to body surface area (EDV index, EDVI), end-systolic volume index (ESVI), and ejection fraction (EF) of the left ventricle were obtained. Delayed enhancement involving subendocardial myocardium was considered typical (TDE) while enhancement apparently not involving subendocardium in its typical location was considered atypical (ADE). Wilcoxon signed-rank, Mann–Whitney U, and χ² tests were used.

Results

All 30 patients showed TDE prior to surgery but 16 of them (53%) showed ADE after SVR. Before SVR, EDVI (ml/m²) was 171 ± 101 in patients with ADE and 127 ± 41 in patients with TDE, ESVI (ml/m²) was 130 ± 105 and 94 ± 36, EF was 25 ± 6% and 24 ± 9%, respectively, without significant differences (P > 0.347). After SVR, EDVI (ml/m²) was 99 ± 24 and 89 ± 28 (P = 0.275), ESVI (ml/m²) 66 ± 24 and 65 ± 30, respectively, without significant differences (P > 0.275) while EF was 37 ± 12% and 29 ± 13%, respectively, with a near-significant difference (P = 0.077). The increase in EF before/after SVR was significant only for patients with ADE (P = 0.006). Of 20 patients in whom a patch had been used for SVR, 14 showed ADE and 6 TDE; of 10 patients without patch, 2 and 8, respectively (P = 0.010).

Conclusion

ADE was found in about half of SVR patients and was associated with the use of patch and EF improvement.     

Coronary artery plaques: cardiac CT with model-based and adaptive-statistical iterative reconstruction technique

Objectives

To compare image quality of coronary artery plaque visualization at CT angiography with images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model based iterative reconstruction (MBIR) techniques.

Methods

The coronary arteries of three ex vivo human hearts were imaged by CT and reconstructed with FBP, ASIR and MBIR. Coronary cross-sectional images were co-registered between the different reconstruction techniques and assessed for qualitative and quantitative image quality parameters. Readers were blinded to the reconstruction algorithm.

Results

A total of 375 triplets of coronary cross-sectional images were co-registered. Using MBIR, 26% of the images were rated as having excellent overall image quality, which was significantly better as compared to ASIR and FBP (4% and 13%, respectively, all p < 0.001). Qualitative assessment of image noise demonstrated a noise reduction by using ASIR as compared to FBP (p < 0.01) and further noise reduction by using MBIR (p < 0.001). The contrast-to-noise-ratio (CNR) using MBIR was better as compared to ASIR and FBP (44 ± 19, 29 ± 15, 26 ± 9, respectively; all p < 0.001).

Conclusions

Using MBIR improved image quality, reduced image noise and increased CNR as compared to the other available reconstruction techniques. This may further improve the visualization of coronary artery plaque and allow radiation reduction.     

Correlation between tumor size and surveillance of lymph node metastasis for IB and IIA cervical cancer by magnetic resonance images

Purpose

To assess the feasibility of preoperative MRI based measurement of tumor size with regard to lymph node (LN) metastasis in early uterine cervical cancer.

Material and Methods

A retrospective review of patients with FIGO stage IB–IIA cervical cancer who underwent lymphadenectomy was performed. Diagnostic accuracy of MRI in detecting LN metastasis and rate of LN recurrence in terms of tumor size (≤4 cm versus >4 cm) were analyzed. ROC curve analysis was used to determine LN size for differentiating LN metastasis in terms of tumor size. P < 0.05 was considered statistically significant.

Results

Of the 200 patients, 45 (22.3%) had LN metastasis. There was no statistical difference between patients-based and region-specific analysis. The patients with tumor size with >4 cm revealed higher diagnostic accuracy of MRI in detecting LN metastasis (85.4% versus 50.6%, P = 0.023) and rate of LN recurrence (20.0% versus 6.4%, P = 0.031) in than those with size with ≤4 cm, the differences were statistically significant. Discriminant analysis of LN size for the differentiation of metastasis from non-metastasis resulted in cut-off values (11.8 mm; size with >4 cm versus 8.3 mm; size with ≤4 cm) and diagnostic accuracy (84.0% of size with >4 cm versus 72.0% of size with ≤4 cm).

Conclusion

MRI has limited sensitivity, but high specificity in predicting surveillance of LN metastasis in the preoperative early cervical cancer, especially useful tool for patients with tumor size with >4 cm.     

The effect of nuchal cord on nuchal fold thickness measured in the second trimester

Purpose

To find out whether nuchal cord causes an effect on the nuchal skin fold thickness (NFT) measurements, or not.

Patients and methods

A total of 242 fetuses with normal outcomes that had undergone detailed second trimester US scan between 18 and 24 weeks of gestation were included in the study. NFT measurements were made on axial cranial US images passing through the cerebellum and cavum septi pellucidum. To detect nuchal cord, color Doppler imaging was performed on the axial views of the fetal neck. To investigate the differences in NFT measurements of the fetuses with or without nuchal cord, statistical analysis was performed using Mann–Whitney test. P < 0.05 was considered statistically significant.

Results

The study group was divided into two groups: nuchal cord (+) (n: 26) and nuchal cord (−) (n: 216) fetuses. Mean NFT measurements were 4.66 ± 0.64 mm and 4.36 ± 0.79 mm for nuchal cord (+) and nuchal cord (−) fetuses, respectively. Median NFT measurement for nuchal cord (+) fetuses was 4.6 mm, whereas it was 4.4 mm for nuchal cord (−) fetuses. Statistically significant difference was denoted between two groups, in terms of NFT measurements (P = 0.049).

Conclusion

NFT measurements of fetuses with nuchal cord are higher than the NFT measurements of fetuses without nuchal cord. One can conclude that the nuchal cord (+) fetuses with no other anomalies but increased NFT should be re-scanned to see if the increased NFT resolves in the absence of nuchal cord.     

Investigation of renal lesions by diffusion-weighted magnetic resonance imaging applying intravoxel incoherent motion-derived parameters--initial experience

Purpose

Usefulness of biexponentially fitted signal attenuation at different b-values for differentiating the histological characteristics of renal tumors.

Materials and methods

A total of 26 patients with 28 renal masses (histologically proven: 20 clear cell renal cell carcinomas [ccRCC], three transitional cell carcinomas, two oncocytomas, and one papillary RCC) and 30 volunteers with healthy kidneys were examined at 1.5 Tesla using an echo-planar DWI sequence. Using the IVIM model, we calculated the perfusion fraction f and the diffusion coefficient D. Furthermore, the ADC was obtained. These tumor parameters were compared to healthy renal tissue nonparametrically, and a receiver operating characteristic (ROC) analysis was performed.

Results

Healthy renal parenchyma showed higher ADC and D values (p < 0.001) than ccRCC (ADC 1.95 ± 0.10 [SD] μm²/ms, f 18.32 ± 2.52%, and D 1.88 ± 0.11 μm²/ms versus ADC 1.45 ± 0.38 μm²/ms, f 18.59 ± 6.16%, and D 1.34 ± 0.38 μm²/ms). When detecting malignancies the area under the curve for D was higher than for ADC. The f values for ccRCC were higher (p < 0.001) than for non-ccRCC (ADC 1.52 ± 0.47 μm²/ms, f 8.44 ± 1.24%, and D 1.30 ± 0.18 μm²/ms). Both f and D correlated with ccRCC grading.

Conclusion

IVIM imaging is able to provide reliable diffusion values in the human kidney and may enhance the accuracy of tumor diagnosis. The D value was the best parameter to distinguish renal tumors from healthy renal tissue. The f value is promising for determining the histological subgroups.     

Ultrasound-guided diffuse optical tomography (DOT) of invasive breast carcinoma: Does tumour total haemoglobin concentration contribute to the prediction of axillary lymph node status?

Objectives

To prospectively study the ultrasound-guided near-infrared diffuse optical tomography (DOT) findings of the total haemoglobin concentration (THC) detected in invasive breast carcinomas and its contribution to the prediction of axillary lymph node (LN) status.

Methods

A total of 195 invasive breast carcinomas were prospectively studied with DOT before surgery. Lumpectomy or mastectomy with full axillary nodal dissection was performed. Tumour size and THC level were correlated with LN status by a logistic regression analysis.

Results

One hundred twenty-four patients (63.59%) was LN(−) and 71 (36.41%) was LN(+). The average THC was significantly higher in the LN(+) group than in the LN(−) group (252.94 ± 69.19 μmol/L versus 203.86 ± 83.13 μmol/L, P = 0.01). A multivariate analysis showed an independent relationship between the probability of axillary metastasis, elevated THC level (P = 0.01), and tumour size (P = 0.001). The odds ratio with THC ≥ 140 μmol/L was 13.651 (1.781–104.560), whereas that of tumour size with a 1 cm increment was only 1.777 (1.283–2.246).

Conclusions

The THC level and the tumour size are independent and preoperative predictors of axillary nodal status; these variables may improve the diagnosis of patients with lymph node metastasis.     

Virtual non-contrast in second-generation, dual-energy computed tomography: reliability of attenuation values

Purpose

To evaluate the reliability of attenuation values in virtual non-contrast images (VNC) reconstructed from contrast-enhanced, dual-energy scans performed on a second-generation dual-energy CT scanner, compared to single-energy, non-contrast images (TNC).

Materials and methods

Sixteen phantoms containing a mixture of contrast agent and water at different attenuations (0–1400 HU) were investigated on a Definition Flash-CT scanner using a single-energy scan at 120 kV and a DE-CT protocol (100 kV/SN140 kV). For clinical assessment, 86 patients who received a dual-phase CT, containing an unenhanced single-energy scan at 120 kV and a contrast enhanced (110 ml Iomeron 400 mg/ml; 4 ml/s) DE-CT (100 kV/SN140 kV) in an arterial (n = 43) or a venous phase, were retrospectively analyzed. Mean attenuation was measured within regions of interest of the phantoms and in different tissue types of the patients within the corresponding VNC and TNC images. Paired t-tests and Pearson correlation were used for statistical analysis.

Results

For all phantoms, mean attenuation in VNC was 5.3 ± 18.4 HU, with respect to water. In 86 patients overall, 2637 regions were measured in TNC and VNC images, with a mean difference between TNC and VNC of −3.6 ± 8.3 HU. In 91.5% (n = 2412) of all cases, absolute differences between TNC and VNC were under 15 HU, and, in 75.3% (n = 1986), differences were under 10 HU.

Conclusions

Second-generation dual-energy CT based VNC images provide attenuation values close to those of TNC. To avoid possible outliers multiple measurements are recommended especially for measurements in the spleen, the mesenteric fat, and the aorta.