Heterogeneity of contrast effect during intermittent second harmonic myocardial contrast echocardiography in healthy patients

Intermittent harmonic imaging with contrast is increasingly used to detect perfusion defects in patients with coronary disease. To achieve this, image homogeneity and the ability to visualize segments on the lateral and distal portions of the imaging field are important. The objective of this study was to evaluate whether the use of specific postprocessing algorithms, such as background subtraction with color coding and parametric display, allows for improved image homogeneity compared with conventional intermittent second harmonic imaging. For this purpose, 20 participants who were free of cardiac abnormalities and in whom myocardial perfusion should by definition be homogeneously distributed, underwent contrast echocardiography during the constant intravenous infusion of 1.0 ± 0.3 mL/min of perfluorocarbon-enhanced sonicated dextrose albumin. End-systolic ECG-triggered images were obtained from the apical 4-chamber view at pulsing intervals of 300-ms 1, 3, 5, and 8 cardiac cycles. For analysis, each set of images was aligned, averaged, background subtracted, and color coded. Pulsing intervals versus videointensity plots were then generated for each pixel in the images and fitted to an exponential function to produce parametric images of β (an index of microbubble velocity) and A (a measure of myocardial blood volume). The heterogeneity of the contrast effect was evaluated by computing the coefficients of variation in each image. Contrast heterogeneity was >20% with all 4 methods. However, it was greater in gray-scale second harmonic (39 ± 13%) and color-coded (47 ± 16%) images than in parametric images of β and A (24 ± 14 and 24 ± 8%, respectively; both P < .05 vs gray-scale second harmonic and color-coded images). With all 4 methods, basal- and apical-lateral segments contributed most to image heterogeneity, albeit significantly less so with parametric imaging. In conclusion, our data indicate that myocardial opacification is frequently heterogeneous in healthy participants, particularly when using gray-scale second harmonic and background-subtracted with color-coding imaging. Parametric imaging allows reduction, albeit incomplete, of the heterogeneity of the contrast effect and therefore improves image quality. (J Am Soc Echocardiogr 2002;15:1448-52.)     

Perfusion weighted color maps for enhanced visualization of myocardial infarction by MSCT: preliminary experience

Purpose The reliable detection of myocardial perfusion defects and myocardial infarction (MI) is of great interest in the comprehensive workup of coronary artery disease. The aim of this study was to optimize the ability of contrast-enhanced cardiac multislice spiral computed tomography (MSCT) for detecting hypoperfused myocardium as surrogate marker of MI using a newly developed post-processing technique. Methods First a model-based software tool for semi-automated detection of the long axis of the left ventricle and assignment of left-ventricular segments was developed using a region growing algorithm and a point distribution model. To visualize changes of the myocardial contrast enhancement pattern color coding was performed after spreading of the attenuation values. 15 patients (12 men, mean age 57 ± 15 years) with a history of MI underwent cardiac MSCT (16 × 0.75 mm, 120 kV, 550 mA s_eff., 100 ml Iopromide) and contrast enhanced delayed enhanced magnetic resonance imaging (DE-MRI) after administration of 0.2 mmol Gd-DTPA/kg/bodyweight as reference standard. Presence of infarction was assessed from MSCT, post-processed MSCT images and DE-MRI using a 17-segment model of the left ventricle. Results On DE-MRI MI was present in 78/255 myocardial segments. From conventional MSCT images MI was detected in 63/255 segments (5 false positive; sensitivity 74.4%; specificity: 97.1%), while on post-processed images MI was assigned to 74/255 segments (6 false positive; sensitivity 87.2%; specificity: 96.6%). Agreement between DE-MRI and conventional MSCT images for detecting MI was κ = 0.756. Using post-processed images agreement improved to κ = 0.850. Conclusion MSCT detection of hypoperfused myocardium as surrogate for MI can be improved using dedicated post processing algorithms.     

Dual energy CT for evaluation of polycystic kidneys: a multi reader study of interpretation time and diagnostic confidence

Purpose

To compare dual-energy CT (DECT) iodine overlay images with renal mass protocol CT in the evaluation of polycystic kidneys with respect to reading time, diagnostic confidence, and detection of renal lesions that are not definitively benign.

Methods

Following IRB approval, portal venous phase dual-source DECT scans performed between September 2013 and February 2016 from 55 patients (mean age 67 ± 15 years, 31 male, 24 female) with polycystic kidneys (4 or more cysts) were included. For each patient, two image sets were created: (1) DECT post-processed iodine overlay images and (2) simulated renal mass protocol CT images (virtual noncontrast and mixed images). Two radiologists independently retrospectively reviewed both sets at separate time points, evaluating for the presence of lesions that were not definitively benign (enhancing lesions or Bosniak IIF cysts), as well as reading times and Likert scale diagnostic confidence ratings (scaled 1–5) for the presence of non-benign lesions. Reading times were compared with a t test, diagnostic confidence with a McNemar test, and lesion number detection with Cohen’s kappa test.

Results

Iodine overlay images were read faster (mean 55 ± 26 s) than renal mass protocol (mean 105 ± 51 s) (p < 0.001). Readers assigned the highest diagnostic confidence rating in 64% using iodine overlay series, compared to 17% using renal mass protocol (p < 0.0001). The proportion of patients with recorded lesions was not significantly different between methods (p = 0.62).

Conclusions

DECT improves lesion assessment in polycystic kidneys by decreasing reading times and increasing diagnostic confidence, without affecting lesion detection rates.

     

Evaluation of 64Cu Labeled GX1: A Phage Display Peptide Probe for PET Imaging of Tumor Vasculature

Purpose  

Molecular imaging using positron emission tomography (PET) radiotracers targeted to tumor vasculature offers a noninvasive method for early detection of tumor angiogenesis and efficient monitoring of response to anti-tumor vasculature therapy. The previous in vitro results demonstrated that the GX1 peptide, identified by phage display technology, is a tumor vasculature endothelium-specific ligand. In this study, we evaluated a ⁶⁴Cu-labeled GX1 peptide as a potential radiotracer for microPET imaging of tumor vasculature in a U87MG tumor xenografted mouse model.     

正常移植肾血流的三维彩色多普勒成像特征

目的探讨正常移植肾血流的三维彩色多普勒成像特征。方法功能正常的同种异体移植肾患者22例；仪器为Acuson X／P 128彩色多普勒超声诊断仪(探头频率3.5MHz)和Tom Tec Echoscan 4．2三维彩色多普勒图像处理工作站，采用磁场空间定位自由扫查系统进行三维图像获取，脱机后进行移植肾血流的三维图像重建与显示。结果移植肾血流的三维彩色多普勒图像特征为，可以立体地显示整个肾脏的血管树结构及血管变异特征。结论三维彩色多普勒超声成像技术能够对肾脏血管进行完整、直观、立体地显示，是对二维超声切面成像的一个有意义的改进和提高。     

Application of color Doppler ultrasonography to ulcerative colitis

We used color Doppler ultrasonography (US) to evaluate bowel wall thickening in ulcerative colitis and to determine the value of this modality in this application. Twelve patients (6 men and 6 women) with ulcerative colitis underwent both gray-scale and color Doppler US. Bowel wall thickness and wall echotexture were recorded by gray-scale US, and the presence of intramural color Doppler flow and arterial signal were evaluated by color Doppler US. Color Doppler flow was graded as ‘weak’ or ‘abundant’, and resistive index was calculated; clinical severity of disease activity was also graded, and serum CRP level was measured. Variation in serum CRP levels and intramural color Doppler flow according to clinical severity, and the correlations between serum CRP levels and the number of blood flow signals were statistically significant. In 10 of the 12 patients, analysis of the Doppler waveform showed an arterial blood flow signal, and mean resistive index value was determined to be 0.550. We thus conclude that information provided by gray-scale and color Doppler US is useful in evaluating bowel wall thickening in ulcerative colitis.     

Sonographic findings in glomus tympanicum tumor

A glomus tympanicum tumor that is associated with a visible retrotympanic mass is the most frequent cause of pulsatile tinnitus. The preoperative diagnostic approach to this lesion includes a meticulous physical examination as well as high-resolution CT, magnetic resonance angiography, and digital angiography, which can also be used for preoperative embolization. We report the use of color transcranial Doppler sonography in the evaluation of glomus tympanicum tumor in a 67-year-old woman with a 3-year history of left tinnitus. An otoscopic examination revealed a reddish pulsatile mass behind an intact tympanic membrane. No lesions were visualized on gray-scale sonography. Contrast-enhanced color transcranial Doppler sonography showed a vascular ovoid mass that measured 2 x 1 x 1 cm; spectral analysis of the lesion revealed arterial flow with a low resistance index. Color transcranial Doppler sonography helped define the dimensions and vascular characteristics of the lesion.     

Splenic lymphangioma: US and CT diagnosis and clinical manifestations

BACKGROUND AND METHODS: We tried to determine the role and problems of gray-scale sonography (US), computed tomography (CT), and color Doppler sonography in the diagnosis of splenic lymphangioma on the basis of our experience with seven adult cases with this relatively rare tumor. RESULTS: (1) The whole spleen was replaced by a collection of cysts of different sizes with or without calcifications in six patients. In these patients, color Doppler sonography showed the intrasplenic arteries and veins running along the cyst walls. (2) The enlarged spleen occupied the whole upper abdomen and contained numerous small cysts in one patient. The patient was initially diagnosed as having a pancreatic tumor because of the location, but color Doppler sonography clearly demonstrated two vessels (artery and vein) running parallel from the center of the mass. This characteristic vascular structure led to the determination that the mass was the markedly enlarged spleen. (3) The splenic lesion was isolated in six patients but was associated with mesenteric and pleural lymphangioma in one symptomatic patient. CONCLUSIONS: (1) When US shows multiple cysts of different sizes in the spleen, the diagnosis of splenic lymphangioma is not difficult to make with US and CT alone. (2) Color Doppler sonography is a very useful tool to increase diagnostic confidence because it demonstrates the vasculature of the mass. (3) When examining patients with splenic lymphangioma, one should consider the possibility of multiorgan involvement.     

Quality of routine diagnostic abdominal images generated from a novel detector-based spectral CT scanner: a technical report on a phantom and clinical study

Purpose

To evaluate the image quality of routine diagnostic images generated from a novel detector-based spectral detector CT (SDCT) and compare it with CT images obtained from a conventional scanner with an energy-integrating detector (Brilliance iCT), Routine diagnostic (conventional/polyenergetic) images are non-material-specific images that resemble single-energy images obtained at the same radiation,

Methods

ACR guideline-based phantom evaluations were performed on both SDCT and iCT for CT adult body protocol. Retrospective analysis was performed on 50 abdominal CT scans from each scanner. Identical ROIs were placed at multiple locations in the abdomen and attenuation, noise, SNR, and CNR were measured. Subjective image quality analysis on a 5-point Likert scale was performed by 2 readers for enhancement, noise, and image quality.

Results

On phantom studies, SDCT images met the ACR requirements for CT number and deviation, CNR and effective radiation dose. In patients, the qualitative scores were significantly higher for the SDCT than the iCT, including enhancement (4.79 ± 0.38 vs. 4.60 ± 0.51, p = 0.005), noise (4.63 ± 0.42 vs. 4.29 ± 0.50, p = 0.000), and quality (4.85 ± 0.32, vs. 4.57 ± 0.50, p = 0.000). The SNR was higher in SDCT than iCT for liver (7.4 ± 4.2 vs. 7.2 ± 5.3, p = 0.662), spleen (8.6 ± 4.1 vs. 7.4 ± 3.5, p = 0.152), kidney (11.1 ± 6.3 vs. 8.7 ± 5.0, p = 0.033), pancreas (6.90 ± 3.45 vs 6.11 ± 2.64, p = 0.303), aorta (14.2 ± 6.2 vs. 11.0 ± 4.9, p = 0.007), but was slightly lower in lumbar-vertebra (7.7 ± 4.2 vs. 7.8 ± 4.5, p = 0.937). The CNR of the SDCT was also higher than iCT for all abdominal organs.

Conclusion

Image quality of routine diagnostic images from the SDCT is comparable to images of a conventional CT scanner with energy-integrating detectors, making it suitable for diagnostic purposes.

     

Contrast-enhanced ultrasonography with Sonazoid for evaluation of renal microcirculation

Purpose  The renal medullary microcirculation plays an important role in regulating sodium and water excretion, and its impairment is closely associated with various renal diseases. Contrast-enhanced ultrasonography (CEUS) using Sonazoid has not yet been reported as a method for evaluating the renal microcirculation; consequently, this study was carried out to reveal the characteristics of renal microcirculation using CEUS with Sonazoid. Methods  CEUS was performed on three healthy volunteers after they had fasted for at least 6 h. A GE LOGIQ7 ultrasound unit was used with a 2.0- to 5.5-MHz convex probe. Within approximately 1 min of intravenous injection of 0.0050 ml/kg Sonazoid, contrast images of the right kidney were acquired using a coded phase-inversion mode. Time-intensity curves were calculated for the cortex and medulla. Results  Peak contrast intensity was significantly higher in the cortex (−56.4 ± 1.9 dB) than in the medulla (−66.7 ± 1.7 dB; P < 0.005). Peak times were significantly earlier in the cortex (17.4 ± 3.7 ms) than in the medulla (28.8 ± 6.3 ms; P < 0.05). Conclusion  CEUS using Sonazoid enables differentiation between the cortical and medullary microcirculation and is useful in clarifying renal pathophysiology and pharmacology.     

彩色多普勒超声对子宫下段切口处早期胚胎着床的诊断价值

目的探讨子宫下段剖腹产切口处早期胚胎着床的灰阶超声及彩色多普勒超声的特征. 方法 28例子宫下段剖腹产切口处早期妊娠的患者均行超声检查,记录各病例的二维图像及收缩期峰值血流速度和血流阻力指数.结果子宫下段剖腹产切口处早期胚胎着床的二维图像具有特征性表现,部分病例彩色多普勒频谱表现为高速低阻特征.结论彩色多普勒超声是无创性诊断子宫下段切口处早期妊娠的可靠方法.     

Evaluation of ureterocele with Doppler sonography

Ureterocele is a common disorder characterized by cystic dilatation of the terminal submucosal portion of 1 or both ureters. Conventional imaging modalities for the diagnosis of ureterocele include intravenous urography and voiding cystourethrography; gray-scale sonography, augmented by color Doppler and spectral analysis studies, can be useful in diagnosing and managing this condition as well. We describe the diagnosis of ureterocele using transvaginal gray-scale and color Doppler sonography with spectral analysis in 2 women. Color Doppler sonography demonstrated urine flow into the bladder, and spectral analysis was used to measure the flow velocity. Together, these modalities can provide additional information about urinary flow dynamics, aid in implementing treatment for patients with ureterocele, and eliminate the need for invasive diagnostic procedures.     

Color Doppler sonographically guided transthoracic needle aspiration of lung and mediastinal masses.

OBJECTIVE: This study investigated the diagnostic value of color Doppler sonographically guided transthoracic needle aspiration in lung and mediastinal masses. METHODS: B-mode and colorDoppler sonographic images were obtained in 48 patients with mediastinal or peripheral pulmonary tumors. Color Doppler sonography was used to show the vascular structures before the transthoracic needle aspiration procedure. It was also used to locate the needle tip during the procedure by showing the twinkling sign. This maneuver was performed with motion of the inner stylet. Pathologic and microbiological examination of the aspirates was made. RESULTS: Vascular structures were detected in 37 cases on color Doppler images and in 10 cases on B-mode images. Similarly, the needle tip was observed in 39 cases on color Doppler images but in only 9 cases on B-mode images. No complications were observed except partial pneumothorax in 2 cases. The method had sensitivity of 90.0%, specificity of 87.5%, a positive predictive value of 97.2%, a negative predictive value of 63.6%, and diagnostic accuracy of 89.6%. CONCLUSIONS: Color Doppler sonographically guided transthoracic needle aspiration is a safe diagnostic method in malignant lung tumors, especially peripheral tumors, because of its ability to differentiate vascular structures within a tumor before the transthoracic needle aspiration procedure. It provides additional information about the location of the needle tip.     

Preoperative imaging of lower extremity varicose veins: color coded duplex sonography or venography.

We prospectively examined 137 limbs in 112 consecutive patients with clinical evidence of severe varicosis by color coded duplex sonography and ascending venography (including varicography in 48 limbs) to evaluate the diagnostic capabilities of color coded duplex sonography in the assessment of venous anatomy, variant varicosis, postthrombotic changes, and incompetence of the superficial and perforating venous system. Additionally, descending venography was performed in the first 52 limbs and compared to color coded duplex sonography in the diagnosis of deep and superficial venous reflux. Variant venous anatomy (21 cases) was missed in two limbs and misinterpreted in one limb by ascending venography compared to surgery. Color coded duplex sonography was inconclusive in two cases. Variant varicosis (59 cases) was missed in seven surgically proved cases by venography and in one case by color coded duplex sonography. Color coded duplex sonography was inconclusive in five cases. Ascending venography was slightly superior to color coded duplex sonography in the detection of postphlebitic changes. Good agreement was found between color coded duplex sonography and descending venography in the grading of superficial (k = 0.75) and deep venous reflux (k = 0.79). Excellent agreement was found between ascending venography in the grading of long (k = 0.96) and short (k = 0.94) saphenous vein reflux. More incompetent perforating veins were detected by ascending venography, (and varicography) than by color coded duplex sonography, but the latter technique allows direct preoperative marking of the skin, which is beneficial for the surgeon. We conclude that color coded duplex sonography is a valuable imaging tool before venous stripping and is capable of replacing invasive ascending and descending venography. Only patients with inconclusive color coded duplex sonographic results (e.g., complex variant venous anatomy) should proceed to venography.     

Green Tagging in Displaying Color Doppler Aliasing: A Comparison to Standard Color Mapping in Renal Artery Stenosis

To quantitatively assess the contrast-to-noise ratio (CNR) of green tagging and standard color flow images in displaying fast flow velocity, we retrospectively reviewed 20 cases of hemodynamically significant renal artery stenosis (RAS) detected by renal color Doppler ultrasound and confirmed with digital subtraction angiography. At the site of RAS, blood flow with high velocity that appeared as aliasing on color flow images was computationally analyzed with both green tagging and standard color mapping. To assess the difference in the CNR between normal background flow and the aliased signal as a function of visualizing aliasing between the two color mappings, we used GetColorpixels (Chongqing Medical University, Chongqing, China) to count the values in the color channels after segmenting color pixels from gray-scale pixels. We then calculated the CNR in each color channel—red, green, and blue (RGB)—in the aliasing region on green tagging and standard color mapping. The CNRs in the red, green and blue channels were 0.35 ± 0.44, 1.11 ± 0.41 and 0.51 ± 0.19, respectively, on standard color mapping, and 0.97 ± 0.80, 4.01 ± 1.36 and 0.64 ± 0.29, respectively, on green tagging. We used a single-factor analysis of variance and two-tailed t-test to assess the difference in CNR in each color channel between the two color mappings at the site of RAS. With these comparisons, there was no significant difference in the CNR in the red or blue channel between green tagging and standard color mapping (p > 0.05). However, there was a statistically significant difference in the CNR in the green channel between the two color mappings (p = 0.00019). Furthermore, the CNR measured in the green channel on the green tagging image was significantly higher than the CNRs in all other color channels on both color mapping images (p = 0.000). Hence, we conclude that green tagging has significantly higher visibility as a function of high-velocity flow than standard color mapping. The use of green tagging may improve the ability to detect RAS with color Doppler ultrasound.     

High-intensity focused ultrasound ablation assisted using color Doppler imaging for the treatment of hepatocellular carcinomas

Purpose

We evaluated the usefulness of color Doppler flow imaging to compensate for the inadequate resolution of the ultrasound (US) monitoring during high-intensity focused ultrasound (HIFU) for the treatment of hepatocellular carcinoma (HCC).

Materials and methods

US-guided HIFU ablation assisted using color Doppler flow imaging was performed in 11 patients with small HCC (<3 lesions, <3 cm in diameter). The HIFU system (Chongqing Haifu Tech) was used under US guidance. Color Doppler sonographic studies were performed using an HIFU 6150S US imaging unit system and a 2.7-MHz electronic convex probe.

Results

The color Doppler images were used because of the influence of multi-reflections and the emergence of hyperecho. In 1 of the 11 patients, multi-reflections were responsible for the poor visualization of the tumor. In 10 cases, the tumor was poorly visualized because of the emergence of a hyperecho. In these cases, the ability to identify the original tumor location on the monitor by referencing the color Doppler images of the portal vein and the hepatic vein was very useful. HIFU treatments were successfully performed in all 11 patients with the assistance of color Doppler imaging.

Conclusion

Color Doppler imaging is useful for the treatment of HCC using HIFU, compensating for the occasionally poor visualization provided by B-mode conventional US imaging.     

Differential diagnosis of hepatic cystic lesions with gray-scale and color Doppler sonography

PURPOSE: This study was conducted to evaluate the effectiveness of sonography, especially color Doppler sonography, in the differential diagnosis of cystic hepatic lesions. METHODS: Ninety-two pathologically or clinically proven hepatic cystic lesions (20 cystic malignancies, 24 abscesses, and 48 simple cysts) were evaluated with gray-scale and color Doppler sonography. The sonographic features were analyzed retrospectively. The percentage, sensitivity, specificity, and positive and negative predictive values of the sonographic features of each disease category were calculated. RESULTS: On gray-scale sonography, the simple cysts were easily distinguished from cystic malignancies and abscesses. While no significant differences were found between hepatic cystic malignancies and hepatic abscesses with respect to the number, shape, margin status, and presence of thick wall of the lesion, the presence of septation and mural nodules was significantly higher in the cystic malignancies than in abscesses. The sensitivity and specificity of color Doppler sonography in differentiating cystic malignancies from abscesses and simple cysts were 85% and 96%, respectively. CONCLUSIONS: Color Doppler sonography provides information about blood flow that supplements that gained on gray-scale sonography, and the presence of color signals in the solid portion of the cystic lesions carries a high diagnostic value in differentiating hepatic cystic malignancies from abscesses and simple cysts.     

Color Doppler imaging of the prostate: important adjunct to endorectal ultrasound of the prostate in the diagnosis of prostate cancer

The purpose of this article is to evaluate color Doppler imaging (CDI) as an adjunctive tool to gray-scale ultrasound (US) in the diagnosis of prostate cancer and to correlate CDI-positive lesions to cancer grade. We retrospectively analyzed 619 consecutive patients who underwent prostate US, CDI, and biopsy because of abnormal digital rectal examination results or prostate-specific antigen levels. All had directed (into a specific lesion) biopsies or directed biopsies along with systematic four-quadrant or sextant biopsies, or systematic biopsy alone. Color Doppler imaging was compared with gray-scale findings and histologic results. There were 222 (35.9%) biopsy-proven cancers (n = 197) or prostatic intraepithelial neoplasia (n = 25). Of these, 106 (47.7%) had color-flow abnormalities. Of these 106 patients, 26 (24.5%), or 11.7% of all cancer patients, had relatively normal gray-scale US findings but had focal CDI abnormalities as the method of identification. Overall, 76.9% of these were moderate to high Gleason grades and were considered clinically significant lesions. Color Doppler imaging can identify a large number (11.7%) of clinically significant prostate cancers that are poorly seen by gray-scale US. Positive lesions on CDI are of clinical importance because 76.9% are histologically, moderately, or poorly differentiated. We recommend that CDI be used in all diagnostic and biopsy-guided US examinations of the prostate.     

3-dimensional sonographic analysis based on color flow Doppler and gray scale image data: a preliminary report.

This paper presents preliminary results of a technique that permits acquisition and display of three-dimensional (3D) anatomy using data collected from color flow Doppler and gray scale image sonography. 3D sonographic image data were acquired as two-dimensional planar images with commercially available equipment. A translational stage permitted the transducer position and orientation to be determined. Color flow sonographic video image data were digitized into a PC-AT computer along with transducer position and orientation information. Color flow velocity and gray scale data were separated, 3D filtered, and thresholded. A surface rendering program was used to define the vessel blood-lumen interface. Planar slices of arbitrary orientation and volume rendered images were displayed interactively on a graphics workstation. The technique was demonstrated in a lamb kidney in vitro and for the carotid artery at the bifurcation in vivo. Our results demonstrate the potential of 3D sonography as a technique for visualization of anatomy. Color flow data offer direct access to the vascular system, facilitating 3D analysis and display. 3D sonography offers potential advantages over existing diagnostic studies in that it is noninvasive, requires no intravenous contrast material, offers arbitrary plane extraction and review after the patient has completed the examination, and permits vascular anatomy to be visualized clearly via rendered images.     

Image quality and diagnostic accuracy of complex-averaged high b value images in diffusion-weighted MRI of prostate cancer

Purpose

To evaluate the impact of complex-averaging on image quality (IQ) and diagnostic accuracy of acquired and calculated high b value (aHBV, cHBV) images in diffusion-weighted prostate MRI.

Materials and methods

This retrospective study included 84 patients who underwent multiparametric prostate MRI at 3 Tesla without endorectal coil. DWIs were acquired at three different b values which included two lower b values (b = 50,900 s/mm²) and one higher b value (aHBV at 2000 s/mm²). The acquired data were postprocessed to generate two different types of trace-weighted images—using conventional magnitude-averaging and complex-averaging. Using lower b values (b = 50,900 s/mm²) from both conventional and complex-averaged image sets, cHBV images (b = 2000 s/mm²) and ADC maps were derived. All image sets were reviewed by two radiologists in different reading sessions to assess image quality and PIRADS. The diagnostic accuracy of different image sets for the detection of prostate lesions was performed by correlating PIRADS and Gleason scores.

Results

Complex-averaging did not impact ADC values of the prostate lesions compared to magnitude-averaging (P = 0.08). Complex-averaging improved image quality of acquired high b value and calculated high b value images (P < 0.0001). Complex-averaging also improved the level of confidence (LOC) of the acquired high b value for both readers (P < 0.0001, P < 0.05), but only for reader A in calculated high b value (P < 0.0001). The image quality of calculated high b value images was not significantly different than acquired high b value images. The dataset combining complex-averaging and calculated high b value provided the highest diagnostic accuracy (but not statistically significant) for detection of the significant prostate lesion compared to the magnitude-averaged acquired high b value (79.55% vs. 72.73%; P = 0.317). The mean acquisition time for b = 2000 s/mm² sequence (aHBV) was 6 min 30 s (± 1 min 16 s) out of a total of 28 min 31 s (± 4 min 26 s) for the entire mp-MRI protocol (approximately 25% of total scan time).

Conclusion

Complex-averaging provides better image quality and level of confidence without significant impact on ADC values and diagnostic accuracy for detection of the significant prostate lesions . The calculated high b value images are also comparable to (and can substitute) the acquired high b value images which can help in reducing the imaging time.