Sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach in the lumbar region

Objectives

The use of ultrasound to guide peripheral nerve blocks is now a well-established technique in regional anaesthesia. However, despite reports of ultrasound guided epidural access via the paramedian approach, there are limited data on the use of ultrasound for central neuraxial blocks, which may be due to a poor understanding of spinal sonoanatomy. The aim of this study was to define the sonoanatomy of the lumbar spine relevant for central neuraxial blocks via the paramedian approach.

Methods

The sonoanatomy of the lumbar spine relevant for central neuraxial blocks via the paramedian approach was defined using a “water-based spine phantom”, young volunteers and anatomical slices rendered from the Visible Human Project data set.

Results

The water-based spine phantom was a simple model to study the sonoanatomy of the osseous elements of the lumbar spine. Each osseous element of the lumbar spine, in the spine phantom, produced a “signature pattern” on the paramedian sagittal scans, which was comparable to its sonographic appearance in vivo. In the volunteers, despite the narrow acoustic window, the ultrasound visibility of the neuraxial structures at the L3/L4 and L4/L5 lumbar intervertebral spaces was good, and we were able to delineate the sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach.

Conclusion

Using a simple water-based spine phantom, volunteer scans and anatomical slices from the Visible Human Project (cadaver) we have described the sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach in the lumbar region.Ultrasound is frequently used to guide central venous cannulation [1] and peripheral nerve blocks [2,3]. However, published data suggest that it is rarely used for imaging the spine or for central neuraxial blocks (CNBs; epidural and spinal injections) [4], which is surprising considering that there are data suggesting that an ultrasound examination prior to epidural access (pre-puncture scan, preview scan or scout scan) improves technical [5-7] and clinical [7,8] outcomes and also the learning curve of obstetric epidural anaesthesia [9]. Despite these encouraging results, we believe that there are very few anaesthetists who currently perform a preview scan prior to epidural catheterisation [5,7] or real-time ultrasound-guided (USG) CNBs [6,10]. This is quite interesting considering that emergency physicians are able to interpret ultrasound images of the spine [11] and are performing lumbar puncture using ultrasound in the accident and emergency department [11,12]. Reasons for this paucity of data or a lack of interest in USG CNBs in regional anaesthesia are not clear, but the authors believe it may be due to a lack of understanding of spinal sonoanatomy. The aim of this study was to describe the sonoanatomy relevant for USG CNBs via the paramedian approach in the lumbar region.     

Quantitative MRI measurements of the Achilles tendon in spondyloarthritis using ultrashort echo times

Objectives

Tendon involvement is common in spondyloarthritis. The MRI signal from the Achilles tendon has been used to quantify mechanical tendinopathy; however, conventional MRI is limited by the short T₂ of normal tendon. Short and ultrashort echo time (UTE) MRI have the potential to better measure signal intensity reflecting changes in T₂ or gadolinium enhancement. Furthermore, UTE images could be used for normalisation to reduce variability. The aim of this work was to investigate such techniques in patients with spondyloarthritis (SpA).

Methods

The Achilles tendons of 14 healthy volunteers and 24 patients with symptomatic spondyloarthritis were studied. Combined UTE (TE=0.07 ms) and gradient echo (TE=4.9 ms) images were acquired before and after intravenous gadolinium together with pre-contrast gradient echo images (TE=2 ms). The signal intensity from a region of interest in the Achilles tendon above the calcaneus was measured. The relative enhancement at echo times of 0.07 ms (RE_0.1) and 4.9 ms (RE₅) were calculated. The ratios of the signal intensities from both 4.9 ms and 2 ms gradient echo images to the signal intensity from the UTE image were calculated (RTE₅ and RTE₂ respectively).

Results

Interobserver intraclass correlation coefficients were excellent (≥0.97). The contrast-to-noise ratio was higher for enhancement on UTE images than on gradient echo images. RE_0.1, RTE₅ and RTE₂ were significantly higher in SpA patients than controls.

Conclusion

Signal intensity ratios using UTE images allow quantitative measurements to be made which are sensitive to tendon T₂ or contrast enhancement and which are increased in spondyloarthritis. They therefore have the potential for use as measures of tendon disease in spondyloarthritis.A cardinal manifestation of seronegative spondyloarthritis (SpA) is inflammation at tendons or ligaments near their insertions, which is well described at many disease sites [1]; the Achilles tendon is the largest such structure in the body. SpA is associated with various MRI findings, including changes within and around the tendon near its insertion, and erosion and oedema of the adjacent bone [2].Conventional MRI has been used to study the Achilles tendon in patients with mechanical tendinopathy and scoring systems have been devised that correlate with surgical outcome [3]. Techniques for quantifying Achilles tendinopathy in these patients based on signal intensity have been shown to correlate with pain and functional impairment [4]. However, measurements of signal intensity from conventional MRI are limited by the short T₂ of the normal Achilles tendon (1–2 ms) [5-7], which limits the detection of subtle increases in T₂ or contrast enhancement [8]. Short echo time (STE) gradient echo images can detect small increases in T₂ which may occur in mild or early tendinopathy [9]. Ultrashort echo time (UTE) techniques reduce the time between excitation and acquisition still further, to under 100 μs, directly visualising the tendon and enabling the demonstration of contrast enhancement despite the short T₂ relaxation times of the normal tendon.Single measurements of signal intensity are prone to variation (e.g. due to radiofrequency coil inhomogeneities, coil loading and variation between patients). Unenhanced UTE images are insensitive to changes in T₂ due to their short effective echo times and can therefore be used to normalise contrast-enhanced or STE images to give a ratio that is strongly dependent on only contrast enhancement or T₂*.The aim of this work was to investigate such quantitative measurements from the Achilles tendon and to apply them in patients with symptomatic SpA.     

Multiplanar 3D ultrasound imaging to assess the anatomy of the upper airway and measure the subglottic and tracheal diameters in adults

Objective:

To evaluate the feasibility of using three-dimensional (3D) ultrasound to assess the anatomy of the airway.

Methods:

11 young volunteers were recruited for 3D ultrasound and MRI of the airway. 3D ultrasound data were obtained from the level of the true vocal cords, cricoid cartilage and upper trachea. Multiplanar 3D ultrasound images were rendered and compared visually with corresponding MRI and cadaver anatomical sections. The anteroposterior (AP) and transverse diameter of the subglottic space and transverse diameter of the upper trachea were also measured in the 3D ultrasound and MR images and compared.

Results:

The airway anatomy was clearly delineated in the multiplanar 3D ultrasound images. It was also possible to identify the cricothyroid junction, and a simple method to measure the AP diameter of the subglottic space using this landmark is described. We were also able to accurately measure the transverse diameter of the upper trachea, but the transverse diameter of the subglottic space was overestimated using ultrasound. There was a strong correlation for the AP diameter measurement (r=0.94, p<0.05) and moderate correlation for the transverse diameter measurement (r=0.82, p=0.002) of the subglottic space, and a strong correlation for the transverse diameter measurement (r=0.91, p<0.05) of the upper trachea, in the ultrasound and MR images.

Conclusion:

The anatomy of the adult airway can be assessed using 3D ultrasound. It can also be used to accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.

Advances in knowledge:

This is the first report to describe the use of 3D ultrasound to evaluate the anatomy of the upper airway and accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.Ultrasound imaging of the airway has been described [1–6], but the majority of the published data involve the use of two-dimensional (2D) ultrasound, which allows examination of the airway in only the transverse or sagittal axis [2,7,8]. There is also a paucity of data correlating the sonoanatomy of the airway [2,7] with an alternative imaging modality [2]. Three-dimensional (3D) ultrasound imaging is currently available and provides simultaneous images of an area of interest (volume) in multiple orthogonal (perpendicular) planes [9]. Preliminary experience with 3D ultrasound suggests that the spatial anatomical information obtained is more detailed [9] than with 2D ultrasound, and the same may apply for imaging of the airway. Currently, there are no published data on 3D ultrasound imaging of the airway. The aim of this pilot study was to evaluate the feasibility of using 3D ultrasound to delineate the anatomy of the upper airway and correlate the sonoanatomy with cadaver anatomical sections and volunteer MR images of the airway. A secondary objective was to measure the subglottic and tracheal diameters in the multiplanar 3D ultrasound images.     

Factors influencing the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography: correlation with biopsy and radical prostatectomy specimens

Objectives

This study was designed to identify factors that influenced the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography (CETRUS).

Methods

139 patients suspected of prostate cancer were evaluated with CETRUS followed by systematic and targeted transrectal ultrasound-guided biopsies. The degree of enhancement of the lesions was objectively measured using peak intensity with time–intensity curve analysis software. Ultrasound findings were correlated with clinical characteristics as well as biopsy and radical prostatectomy findings.

Results

Prostate cancers were detected in 230 biopsy sites from 91 patients. The mean peak intensity value of prostate cancer was significantly higher than that of the benign lesions (9.82±3.73 vs 7.51±2.97; p<0.001), and the peak intensity value of the cancer foci varied across the prostate. The mixed model analysis revealed that the location and Gleason score of tumour foci were the influencing factors of the peak intensity value, and the former had a stronger influence upon peak intensity than the latter (p=0.000 and 0.040, respectively). However, age, prostate volume or serum prostate-specific antigen of the patient had no significant influence on the peak intensity value (p>0.05). Furthermore, the peak intensity value of tumours larger than 5 mm diameter was significantly higher than tumours of 5 mm or smaller diameter (9.28±2.46 vs 6.69±2.65; p<0.001).

Conclusions

The prostate cancer lesions with a higher Gleason score and larger tumour size which were located in the lateral peripheral zone (PZ) were more likely to show a marked enhancement. Lesions with lower peak intensity that are located in the medial PZ should also be treated as suspicious.Prostate cancer is the most commonly diagnosed cancer in males, accounting for 28% of new cancer diagnoses in males and 11% of cancer-related deaths, with an expected 32 050 prostate cancer-specific mortalities in 2010 [1]. The imaging of prostate cancer is central to early detection and staging. However, it is generally acknowledged that detection and localisation of prostate tumours using greyscale ultrasound is poor, because suspicious hypoechoic areas represent cancer in only 9–53% of cases [2-3]. Furthermore, up to 30% of prostate cancers are isoechoic [4-5]. Conventional prostate ultrasound has little advantage over digital rectal examination for detecting malignant areas. Consequently, new strategies for prostate cancer detection are required. Contrast-enhanced ultrasound (CEUS) is a real-time imaging technique with the capability of visualising perfusion patterns [6-8]. This imaging technology has revealed promising perspectives in the diagnosis of prostate cancer owing to its ability to improve the visualisation of tumour vascularity. Several studies have reported that CEUS-targeted biopsy detected more cancer than systematic biopsy by identifying the area with greatest enhancement of the prostate [9-12]. In a recent study reported by Tang et al [13], the haemodynamic parameters such as time to enhancement (AT), time to peak intensity (TTP) and peak intensity (PI) were compared between 44 prostate cancer lesions and 47 benign ones. However, the peak enhancement intensity was found to be the optimal discriminatory parameter. Based on these previous findings, the degree of enhancement of the tumour foci plays a significant role in cancer detection on CEUS imaging.Although CEUS detected more cases of cancer than baseline imaging, the cancer detection rate still remains far from satisfactory [14-15]. Halpern et al [14] compared areas of increased enhancement in the prostate at CEUS with pathological examination and found that only 8 of 31 cancer foci were detected at baseline greyscale imaging, and contrast-enhanced imaging allowed identification of 13 of the 31 cancers (42% sensitivity). In their research, more than half of all cancers failed to show an abnormal enhancement, which indicated that the prostate cancer foci were not always shown as marked enhancement. Mitterberger et al [11] stated that the cancer with increased enhancement found by means of targeted biopsy had a higher mean Gleason score than the ones found by random biopsies, which suggested that the Gleason score of the prostate cancer could influence the degree of enhancement of the tumour to a certain extent. However, to our knowledge, factors influencing the degree of enhancement of the tumour have not yet been systematically investigated. In the present study, we evaluated the peak intensity of prostate cancers during the administration of the ultrasound contrast agent, and aimed to identify factors that influenced the degree of enhancement of prostate cancer on CEUS imaging. We hypothesised that identifying factors influencing the tumour peak intensity value could be useful for differential diagnosis of benign and malignant lesions in the CEUS examination, which would allow for a more accurate determination of the target sites during the subsequent biopsy procedure.     

Accuracy of contrast-enhanced ultrasound in the detection of bladder cancer

Objective

To assess the accuracy contrast-enhanced ultrasound (CEUS) in bladder cancer detection using transurethral biopsy in conventional cystoscopy as the reference standard and to determine whether CEUS improves the bladder cancer detection rate of baseline ultrasound.

Methods

43 patients with suspected bladder cancer underwent conventional cystoscopy with transurethral biopsy of the suspicious lesions. 64 bladder cancers were confirmed in 33 out of 43 patients. Baseline ultrasound and CEUS were performed the day before surgery and the accuracy of both techniques for bladder cancer detection and number of detected tumours were analysed and compared with the final diagnosis.

Results

CEUS was significantly more accurate than ultrasound in determining presence or absence of bladder cancer: 88.37% vs 72.09%. Seven of eight uncertain baseline ultrasound results were correctly diagnosed using CEUS. CEUS sensitivity was also better than that of baseline ultrasound per number of tumours: 65.62% vs 60.93%. CEUS sensitivity for bladder cancer detection was very high for tumours larger than 5 mm (94.7%) but very low for tumours <5 mm (20%) and also had a very low negative predictive value (28.57%) in tumours <5 mm.

Conclusion

CEUS provided higher accuracy than baseline ultrasound for bladder cancer detection, being especially useful in non-conclusive baseline ultrasound studies.Carcinoma of the urinary bladder is the most common malignancy of the urinary tract that must be ruled out in patients with haematuria with negative upper urinary tract findings [1]. Cystoscopy remains the most sensitive method of detecting bladder cancer, but has several limitations: it is an invasive procedure; it is uncomfortable in some patients and it requires sedation or anaesthesia. Conventional ultrasound (US) is one of the imaging techniques used to screen for bladder cancer, but with variable accuracy. The best results are obtained using the latest equipment and new imaging tools such as three-dimensional (3D) ultrasound [2-5]. Angiogenesis is essential to allow growth of malignancies, and the detection of tumoural neovascularisation is one of the keys of imaging modalities to achieve a definite diagnosis. CT and MRI are accurate techniques for bladder cancer detection when they are performed with the injection of intravascular contrast agents. Detection relies on the identification of bladder cancer neovascularisation and recent studies have shown high accuracy with both techniques [6,7]. The introduction of microbubble contrast agents and the development of contrast-specific software have increased the value of ultrasound in the field of oncology [8,9]. Ultrasound contrast agents are strictly intravascular and are very sensitive in revealing tumour microvascularisation, helping in the detection and characterisation of malignancies [10-13]. Recently, the behaviour of bladder cancer has been described after the administration of ultrasound contrast agent, and its diagnosis relies on the detection of hypervascular wall bladder thickening [14].The aim of our study was to retrospectively assess the value of contrast-enhanced ultrasound (CEUS) in bladder cancer detection in a selected high-risk group of patients using transurethral biopsy in conventional cystoscopy as the reference standard and to determine whether CEUS improves the bladder cancer detection rate of baseline ultrasound.     

Early assessment of chronic kidney dysfunction using contrast-enhanced ultrasound: a pilot study

Objective:

We performed a prospective study to evaluate the value of contrast-enhanced (CE) ultrasound in quantitative evaluation of renal cortex perfusion in patients with chronic kidney dysfunction (CKD Stage I–II).

Methods:

The present study was approved by the institutional ethics committee. The study focused on 41 consecutive patients (males, 32; females, 9; mean age, 55.0 ± 5.0 years) with clinical suspicion of CKD (Stages I–II). For both kidneys, CE ultrasound was performed after intravenous bolus injection of 1.0 ml SonoVue® (Bracco Imaging S.p.A., Milan, Italy). Time–intensity curves (TICs) and quantitative indexes were created with Qlab software (Philips, Bothell, WA). 45 healthy volunteers were included as control group. All statistical analyses were performed with SPSS® v. 15.0 software package (SPSS, Chicago, IL). A difference was considered statistically significant with p < 0.05.

Results:

Patients with CKD (Stages I–II) had no obvious change in the shape of TICs. Among all quantitative indexes, the changes of area under the curve (AUC), derived peak intensity (DPI) and slope rate of elevation curve (A) were statistically significant (p < 0.05). DPI <12 dB, A >2 and AUC >1300 dB s had high utility in the evaluation of CKD, with 81%, 73% and 78% specificities and 76%, 73% and 77% sensitivities.

Conclusion:

CE ultrasound might be valuable in the early evaluation of CKD. AUC, A and DPI might be valuable quantitative indexes.

Advances in knowledge:

Quantitative CE ultrasound analysis can be used for the standardized and early evaluation of renal dysfunction.Throughout the world, chronic kidney dysfunction (CKD) is a growing health concern because of its increasing prevalence and incidence rate.¹ Since CKD primarily involves perfusion changes in the renal cortex, assessment of tissue perfusion is an important component for the evaluation of CKD.² Early and detailed visualizations of perfusion changes of the renal cortex yield information about organ viability and function, which would be crucial to make diagnosis and to initiate early drug therapy.³Different non-invasive imaging modalities, such as multidetector CT,⁴ positron emission tomography,⁵ MRI⁶ and single-photon emission CT with ^99mTc-diethylenetriamine pentaacetic acid⁷ are used in the quantifications of tissue perfusions. However, high costs, reduced availability, long examination periods, patients'' exposure to radiation or nuclear tracers limited clinical applications of these techniques.^4–7 Greyscale renal ultrasound combined with colour Doppler flow imaging (CDFI) had become the main non-invasive imaging methods for evaluating the renal anatomy and blood flow.⁸ However, CDFI parameters such as the resistance index (RI) and peak systolic velocity (PSV) provided only indirect macrovasculature parameters, which could not directly assess renal cortex perfusion and were of limited diagnostic use in the CKD.⁹ To date, there was no reliable, accurate and convenient method to determine renal blood perfusion in vivo, thereby leading to difficulty in early and accurate diagnosis of CKD.In recent years, low mechanical index (MI) real-time contrast-enhanced (CE) ultrasound has been proposed as an alternative imaging technique in this area.¹⁰ Because microbubbles are blood-pool agents, when injected intravenously, they remain entirely intravascular, mix uniformly with blood in the circulation and possess the same intravascular rheology as red blood cells.¹¹ The advantages of CE ultrasound include the absence of ionizing radiation or nephrotoxicity, and the widespread availability. When CE ultrasound is performed immediately after a non-conclusive ultrasound study, only a short time was needed to arrive at a final diagnosis.¹² CE ultrasound has been recently used as a new imaging technique for quantifying tissue perfusion changes in the liver,¹³ heart¹⁴ and kidney.¹⁵ The large blood supply of the kidney was a good base for contrast studies, as >90% of kidney blood flow supplied the renal cortex by the renal arterioles and capillaries.¹⁶ Since CE ultrasound microbubbles remain strictly inside the vessels, they can be viewed as blood-pool markers enabling functional imaging of the kidney.¹⁷ The increase in echo signal intensity after microbubble injection may be quantified by dedicated software packages to produce time–intensity curves (TICs). Enhancement-based representations had been used to assess unilateral kidney dysfunction such as in renal artery stenosis by a simple analysis of the tracer concentration curve.¹⁸ These features made low MI CE ultrasound a promising technique in evaluation of renal cortex perfusion.The purpose of this initial study was to evaluate the feasibility of CE ultrasound to assess renal cortex tissue perfusion in the early stages of CKD (Stages I–II) by means of TICs. The diagnostic efficacy gained by quantitative CE ultrasound was compared with that of renal arterial PSV and RI measured by CDFI.     

Application of contrast-enhanced ultrasonography in the diagnosis of skeletal muscle crush injury in rabbits

Objective:

To explore the diagnostic value of quantitative contrast-enhanced (CE) ultrasonography for crush injury in the hind limb muscles of rabbits.

Methods:

A total of 120 New Zealand white rabbits were randomized to receive compression on the left hind limb for either 2 h (n = 56) or 4 h (n = 56) to induce muscle crush injury. Another eight animals were not injured and served as normal controls. CE ultrasonography parameters such as peak intensity (PI), ascending slop, descending slop and area under curve (AUC) were measured at 0.5, 2, 6 and 24 h and 3, 7 and 14 days after decompression.

Results:

Compared with the uninjured muscles, reperfusion of the injured muscles showed early and high enhancement in CE ultrasonography images. The time-intensity curve showed a trend of rapid lift and gradual drop. The PI and AUC values differed significantly among the three groups and were positively correlated with serum and tissue biomarkers. Rabbits of the 4-h compression group showed significantly higher PI and AUC values, and serum and tissue parameters than the 2-h compression group at each time points.

Conclusion:

CE ultrasonography can effectively detect muscle crush injury and monitor dynamic changes of the injured muscles in rabbits. PI and AUC are promising diagnostic parameters for this disease.

Advances in knowledge:

CE ultrasonography might play an important role in the pre-hospital and bedside settings for the diagnosis of muscle crush injury.Muscle crush injury usually occurs during earthquakes, collapse of buildings and heavy whip beatings, and often induces crush syndrome if not treated promptly. Crush injury is estimated to account for 3–20% of all injuries during natural disasters, and the lower limbs are the most frequently affected.¹ Limb crush injury and its complications are life threatening and the most frequent cause of disability and death after earthquakes.²The mortality rate in patients with crush syndrome can be as high as 21%, which is the most dangerous complication of all injuries during disasters.³ Crush syndrome can cause acute kidney injury and acute osteofascial compartment syndrome (AOCS), which are the most life-threatening complications. AOCS has a 47% mortality, and unrecognized AOCS can leave a patient with non-viable limbs requiring amputation.⁴ Severe muscle crush injury can also result in multiple organ dysfunction syndrome, acute respiratory distress syndrome, disseminated intravascular coagulation and severe arrhythmia.⁵ Early diagnosis of muscle crush injury and correct assessment of its severity are critical for good prognosis of patients. However, bedside and pre-hospital diagnosis of crush injury still lacks effective methods.Typical muscle crush injury and related AOCS are usually diagnosed with clinical symptoms, but the sensitivity of this method is very low.^6,7 Impaired microcirculation is the initial pathological change of crushed muscles.⁴ A variety of imaging methods have been used to examine reperfusion of the extremities and therefore detect the presence of muscle crush injury, such as CT, MRI and ultrasonography.^8–11 However, the equipment of CT and MRI is large and inconvenient for bedside or pre-hospital settings or in situ care at the trauma scene. On the contrary, ultrasonography devices can be light, portable and convenient for bedside or traumatic scenes. Ultrasonography also has no radiation. Conventional ultrasonography has been used to determine limb muscle crush injury, rhabdomyolysis and AOCS during the 2008 Sichuan earthquake in China.¹² However, the sensitivity of conventional ultrasonography is low for the diagnosis of extremity crush injury, and its detecting ability of microvascular perfusion is also very poor.¹³Gas-filled microbubbles can significantly augment the back scattered signals and do not leak out of the blood vessel and therefore are used as a contrast agent for Doppler ultrasonography to trace the bloodstream. Contrast-enhanced (CE) ultrasonography has been successfully used to measure microcirculation of the skeletal muscles, such as measurement of muscle perfusion after exercise, and evaluation of muscle perfusion in inflammatory myopathy or peripheral arterial disease.^14–16 However, application of CE ultrasonography in the assessment of microcirculation perfusion in muscle crush injury has rarely been reported.¹⁷In this study, microcirculation of extremities that underwent crush injury were evaluated using CE ultrasonography to investigate the values of CE ultrasonography in diagnosing limb crush injury.     

Brachial plexus assessment with three-dimensional isotropic resolution fast spin echo MRI: comparison with conventional MRI at 3.0 T

Objective

The purpose of our study was to determine whether a three-dimensional (3D) isotropic resolution fast spin echo sequence (FSE-cube) has similar image quality and diagnostic performance to a routine MRI protocol for brachial plexus evaluation in volunteers and symptomatic patients at 3.0 T. Institutional review board approval and written informed consent were guaranteed.

Methods

In this prospective study FSE-cube was added to the standard brachial plexus examination protocol in eight patients (mean age, 50.2 years) with brachial plexus pathologies and in six volunteers (mean age, 54 years). Nerve visibility, tissue contrast, edge sharpness, image blurring, motion artefact and acquisition time were calculated for FSE-cube sequences and for the standard protocol on a standardised five-point scale. The visibility of brachial plexus nerve and surrounding tissues at four levels (roots, interscalene area, costoclavicular space and axillary level) was assessed.

Results

Image quality and nerve visibility did not significantly differ between FSE-cube and the standard protocol (p>0.05). Acquisition time was statistically and clinically significantly shorter with FSE-cube (p<0.05). Pathological findings were seen equally well with FSE-cube and the standard protocol.

Conclusion

3D FSE-cube provided similar image quality in a shorter acquisition time and enabled excellent visualisation of brachial plexus anatomy and pathology in any orientation, regardless of the original scanning plane.Brachial plexus examination remains difficult because of its particular orientation and it is conventionally realised using sequential multiplanar two-dimensional (2D) sequences with various contrasts such as T₁, T₂ and T₂ short tau inversion–recovery (STIR) sequences for fat saturation contrast [1-5]. As a consequence, the acquisition plane is never exactly the right plane to better visualise and analyse the brachial plexus. Three-dimensional (3D) acquisitions allow one either to reconstruct images perpendicular to the plexus or, in double obliquity, to slice through the cords and trunks of the plexus. 3D acquisitions implemented to image the plexus are highly T₂ weighted, like constructive interference in the steady state (CISS)3D, fast imaging with steady-state precession (TrueFISP 3D) or 3D STIR sequences [5-7]. 3D sequences allow a good depiction of compressive nerve root and nerve root avulsions [5]. It has recently been demonstrated that 3D STIR acquisitions are useful for the initial screening of patients with tumoural aetiologies of the brachial plexus. Moreover, they are a valuable adjunct in the detection of space-occupying lesions, yielding better depiction of nerve site compression and providing a better understanding of the pathophysiology [5]. Moreover, 3D STIR sequences can be used as a high-resolution mask to be fused with fraction of anisotropy maps calculated from diffusion tensor imaging data of the plexus [5].A recently introduced technique, 3D fast recovery fast spin echo (FRFSE)-cube, uses variable flip angle refocusing, autocalibrating 2D accelerated parallel imaging and non-linear view ordering to produce high-resolution volumetric image sets [8]. The image data, with approximately 0.7 mm isotropic resolution, can be reformatted in any plane, regardless of the prescribed plane during the image acquisition. The cube technique has been shown in various applications and specifically compared with 2D fast spin echo (FSE) for imaging of the knee, ankle, brain and uterus at 1.5 T [8-13]. Advantages of 3D cube sequences include high image quality and good 3D reconstructions in a shorter acquisition time [8,11]. The improved acquisition efficiency of cube sequences allowing data to be reformatted in arbitrary planes is ideal for complex anatomy such as that found at the brachial plexus level.The purpose of our study was to compare 3D FSE-cube with a standard protocol for brachial plexus imaging using a 3 T system.     

Ipsilateral atrophy of paraspinal and psoas muscle in unilateral back pain patients with monosegmental degenerative disc disease

Objectives

The aim of this study was to assess the cross-sectional area (CSA) of both paraspinal and psoas muscles in patients with unilateral back pain using MRI and to correlate it with outcome measures.

Methods

40 patients, all with informed consent, with a minimum of 3 months of unilateral back pain with or without sciatica and one-level disc disease on MRI of the lumbosacral spine were included. Patients were evaluated with self-report measures regarding pain (visual analogue score) and disability (Oswestry disability index). The CSA of multifidus, erector spinae, quadratus lumborum and psoas was measured at the disc level of pathology and the two adjacent disc levels, bilaterally. Comparison of CSAs of muscles between the affected vs symptomless side was carried out with Student''s t-test and correlations were conducted with Spearman''s test.

Results

The maximum relative muscle atrophy (% decrease in CSA on symptomatic side) independent of the level was 13.1% for multifidus, 21.8% for erector spinae, 24.8% for quadratus lumborum and 17.1% for psoas. There was significant difference (p<0.05) between sides (symptomatic and asymptomatic) in CSA of multifidus, erector spinae, quadratus lumborum and psoas. However, no statistically significant correlation was found between the duration of symptoms (average 15.5 months), patient''s pain (average VAS 5.3) or disability (average ODI 25.2) and the relative muscle atrophy.

Conclusion

In patients with long-standing unilateral back pain due to monosegmental degenerative disc disease, selective multifidus, erector spinae, quadratus lumborum and psoas atrophy develops on the symptomatic side. Radiologists and clinicians should evaluate spinal muscle atrophy of patients with persistent unilateral back pain.Paraspinal and trunk muscles play an important role in the kinetics and balance of the lumbar spine. They are considered as dynamic stabilisers applying their working force by providing stability to the spine–pelvis complex and motion to the spinal units. In addition, psoas is a significant hip flexor. Any decrease in the cross-sectional diameter (CSA) of these muscles could lead to loss of proper biomechanics and may be accompanied by the appearance of back pain [1-5]. Some authors have proposed that pain leads to a sedentary lifestyle and, furthermore, this creates extra muscle atrophy and pain, thus beginning a vicious cycle [6,7].In athletes with regular physical training, an increase in CSA of the paraspinal and trunk muscles has been demonstrated that reflects the improvement of muscle force and endurance [8]. In contrast, prolonged bed rest results in selective atrophy of the multifidus muscle whereas trunk muscles increase their CSA. The latter is probably the effect of shortening of muscle fibres or overactivity during bed rest [9].Many studies on paraspinal musculature have focused on the multifidus muscle because of its unique and segmental innervation [10]. A multifidus bundle''s unisegmental innervation always arises purely from the root exiting below the spinous process from which the fascicles originate, whereas in the other paraspinal muscles innervation is multisegmental. Several studies have demonstrated atrophy of multifidus following trauma, disc herniation or spinal nerve lesion by electromyographic, histological or radiographic measurements [1,11,12]. None of these studies focused on monosegmental degenerative disc disease.This study aims to examine the CSA of all muscles around the lumbar spine in patients with persistent unilateral back pain caused by monosegmental degenerative disc disease and correlate this with their symptoms and period of pain.     

Diffusion tensor imaging in evaluation of thigh muscles in patients with polymyositis and dermatomyositis

Objective:

To explore the diffusion tensor imaging (DTI) characteristics of thigh muscles in patients with polymyositis (PM) and dermatomyositis (DM).

Methods:

12 patients with known PM/DM and 10 healthy volunteers were enrolled in this study. Both DTI and conventional MR sequences were performed on both thighs of all subjects. Apparent diffusion coefficient (ADC), fractional anisotropy (FA) and three eigenvalues were compared between the PM/DM group and the healthy group. One-way analysis of variance and Student''s t-test were used for statistical analyses with a significance of p < 0.05.

Results:

In the healthy group, the vastus intermedius muscle showed the highest ADC value and the gracilis (GA) muscle showed the lowest ADC value. These results were statistically significant when compared with other muscles (p < 0.05). The GA, semi-tendinosus and semi-membranosus muscles showed higher FA values than the other three thigh muscles (p < 0.05). The mean ADC value and three eigenvalues of oedematous muscles in the PM/DM group were higher on average and showed a statistically significant difference when compared with unaffected (non-oedematous muscles in patients) and normal muscles (p < 0.05). There was no statistical difference in the mean FA value between oedematous and normal muscles. The mean ADC, FA and three eigenvalues in unaffected muscles (in patients) showed no statistical differences from those in normal muscles (p > 0.05).

Conclusion:

DTI can be used to quantitatively evaluate the anisotropic diffusion characteristics of muscles in patients with PM/DM.

Advances in knowledge:

A new application of DTI is proposed for inflammatory myopathies. The results show that ADC and the three eigenvalues were significantly different between diseased and normal muscles, a finding of potential value in both diagnosis and treatment monitoring of myopathies.Polymyositis (PM) and dermatomyositis (DM) are two common idiopathic inflammatory myopathies. In the past, the diagnosis of PM/DM depended primarily on clinical features, enzyme levels within the blood, electromyogram and muscle biopsies.^1–3 Recently, MRI has been proven to be valuable in evaluating patients with PM/DM.^4–6 Using traditional sequences, MRI is able to detect muscle oedema and fat infiltration/fatty replacement in muscles, with high spatial resolution and superior soft-tissue contrast compared with other imaging modalities.^7–9However, conventional MR techniques, such as T₂ weighted imaging and short tau inversion recovery, are limited to providing qualitative information, as opposed to quantitative information, which is important for the early detection of inflammatory changes in these diseases. The findings of PM/DM on traditional MRI images are non-specific, making it difficult to distinguish PM/DM from other myopathies on MRI. In addition, the muscular microstructure needs to be evaluated for staging and therapy monitoring in clinical practice.Diffusion tensor imaging (DTI) is an advanced functional MRI technique that has been used to evaluate the anisotropic diffusion characteristics of tissues, such as fibre bundles of white matter and peripheral nerves. Skeletal muscle fibres are cylindrical and well ordered along a specific direction, with the longitudinal axis significantly longer than the transverse axis. Therefore, the diffusion of water molecules in the muscle fibres is faster along the longitudinal axis than along the transverse axis because of the restrictions from the muscle cell membrane (sarcolemma) laterally. Based on these theories, DTI has also been successfully applied in the evaluation of skeletal muscles with quantitative measurements of muscular microstructure and physical function.^10,11In PM/DM, muscle degeneration and inflammatory cell infiltration in the muscle fibres are typical pathological changes that could affect the diffusion of water molecules within muscles. In this study, we aimed to investigate the anisotropic diffusion characteristics of thigh muscles in patients with PM/DM using DTI and to compare it with DTI in healthy volunteers.     

Feasibility study on energy prediction of microwave ablation upon uterine adenomyosis and leiomyomas by MRI

Objective:

To evaluate the feasibility of energy prediction of percutaneous microwave ablation (PMWA) upon uterine leiomyomas and adenomyosis by MRI.

Methods:

63 patients (49 patients with 49 uterine leiomyomas and 14 patients with adenomyosis) who underwent ultrasound-guided PMWA treatment were studied during the period from June 2011 to December 2012. Before PMWA, contrast-enhanced MRI (ceMRI) was performed for all of the patients. Based on the signal intensity (SI) of T₂ weighted MRI, uterine leiomyomas were classified as hypointense, isointense and hyperintense. During ablation, the output energy of the microwave was set at 50 W, and T11a microwave antennas were used. ceMRI was performed within 7 days after PMWA treatment. Non-perfused volume and energy required per unit volume were analysed statistically.

Results:

When unit volume of lesions was ablated, uterine adenomyosis needed more energy than did uterine leiomyomas, and hyperintense uterine leiomyomas needed more energy than did hypointense pattern.

Conclusions:

MRI SI of uterine leiomyomas and uterine adenomyosis can be used to predict PMWA energy.

Advances in knowledge:

The conclusions indicate that MRI SI can be used to perform pre-treatment planning, which will make the treatment more precise.Uterine leiomyomas and adenomyosis are benign lesions that occur most commonly in females of childbearing age. Although many females with uterine leiomyomas and adenomyosis are asymptomatic, as many as 20–65% of them have symptoms^1,2 such as abnormal uterine bleeding, dysmenorrhoea, pelvic pressure, low abdominal pain and infertility. These symptoms often lead to reduced quality of life, as well as loss of work and increased medical costs.³ Hysterectomy has been the main mode of therapy for leiomyomas and adenomyosis. However, medical technology advancements have made less invasive treatment options available, such as uterine artery embolization (UAE),^4–6 high-intensity focused ultrasound (HIFU),^7–9 radiofrequency (RF)¹⁰ and percutaneous microwave ablation (PMWA).^11,12 PMWA is a minimally invasive technique for the treatment of uterine leiomyomas and adenomyosis by inducing tissue necrosis through heat. Previous reports^11,12 have indicated that PMWA provides a feasible, safe and reliable alternative for the treatment of uterine leiomyomas and adenomyosis. However, until now, the energy required per unit volume (EPV) of PMWA in uterine lesions has been unclear, which has limited the widespread use of PMWA therapy. In this study, we sought to investigate the relationship between the MRI signal intensity (SI) of uterine lesions and the EPV of PMWA to better predict PMWA energy before treatment and to make the PMWA procedures standardized.     

Ultrasound-guided combined intermediate and deep cervical plexus nerve block for regional anaesthesia in oral and maxillofacial surgery

Objectives:

We examined the application of an ultrasound-guided combined intermediate and deep cervical plexus nerve block for regional anaesthesia in patients undergoing oral and maxillofacial surgery.

Methods:

A total of 19 patients receiving ultrasound-guided combined intermediate and deep cervical plexus anaesthesia followed by neck surgery were examined prospectively. The sternocleidomastoid and the levator of the scapula muscles as well as the cervical transverse processes were used as easily depicted ultrasound landmarks for the injection of local anaesthetics. Under ultrasound guidance, a needle was advanced in the fascial band between the sternocleidomastoid and the levator of the scapula muscles and 15 ml of ropivacaine 0.75% was injected. Afterwards, the needle was advanced between the levator of the scapula and the hyperechoic contour of the cervical transverse processes and a further 15 ml of ropivacaine 0.75% was injected. The sensory block of the cervical nerve plexus, the analgesic efficacy of the block within 24 h after injection and potential block-related complications were assessed.

Results:

All patients showed a complete cervical plexus nerve block. No patient required analgesics within the first 24 h after anaesthesia. Two cases of blood aspiration were recorded. No further cervical plexus block-related complications were observed.

Conclusions:

Ultrasound-guided combined intermediate and deep cervical plexus block is a feasible, effective and safe method for oral and maxillofacial surgical procedures.     

Brachytherapy for tongue cancer in the very elderly is an alternative to external beam radiation

Background

The result of curative treatment for very elderly patients with tongue carcinoma has not been reported to date. We retrospectively reviewed the results of brachytherapy in 125 the patients aged over 75 years.

Methods

The results of brachytherapy in 125 patients, 75 years old or older, with Stage I or II squamous cell carcinoma of the oral tongue were reviewed. The 125 cases consisted of 31 Stage I and 94 Stage II cases; 67 patients were under 80 years old and 58 were over 80 years old. All patients were treated using low-dose-rate brachytherapy (¹⁹⁸Au/²²²Rn: 59 cases; ¹⁹²Ir: 38 cases; ²²⁶Ra/¹³⁷Cs: 28 cases).

Results

None of the patients stopped treatment during the course of brachytherapy. The 3 year and 5 year control rates of the primary lesions were both 86%. Post-brachytherapy neck node metastasis was diagnosed in 43 cases and radical neck dissection was performed for 24 cases (21 of the 24 cases were under 80 years old). As a result, the 7 year disease-specific survival (DSS) rate for patients aged under 80 years old was 70% and 41% for those over 80 years old (p = 0.03).

Conclusion

The brachytherapy for elderly patients with tongue cancer was safe, and the control of the primary lesion was almost the same as in younger patients. However, modalities available to treat neck node metastasis are limited. More conservative surgical approaches combined with post-operative irradiation may be advocated for neck node metastasis for elderly patients with tongue cancer.Tongue cancer predominantly occurs in older people, and patients with tongue cancer often have physical and/or psychological complications. Because of such comorbidities, most older patients are not considered candidates for curative surgery. Radiotherapy is now one of the most powerful modalities for the treatment of cancer, and several published studies have demonstrated the feasibility of radiotherapy with curative intent for every type of head and neck cancer [1,2]. Because the use of conventional external beam radiotherapy for head and neck cancer has been reported to cause severe collateral effects, several special techniques have particular relevance to the treatment of the head and neck cancer in the elderly [1,3,4]. Brachytherapy is another modality that may be of relevance to the treatment of elderly patients with tongue cancer.We have already reported our experience of the treatment of tongue cancer with brachytherapy alone or in combination with external beam radiotherapy [5-7]. However, since then no data have been reported concerning the outcome of very elderly patients with squamous cell carcinoma of the head and neck treated by brachytherapy. The aim of this study was to investigate the appropriateness of feasible curative treatment by low-dose-rate brachytherapy for early tongue cancer in patients aged over 75 years. This study was approved by the research ethics board committee.     

Treatment and prognosis of angiosarcoma of the scalp and face: a retrospective analysis of 48 patients

Objective

The objective of this study was to retrospectively analyse the treatment results of clinically localised angiosarcoma of the scalp and face.

Methods

The records of 48 patients who were treated between 1987 and 2009 were reviewed. single modality or a combination of surgery, radiotherapy, chemotherapy and immunotherapy were administered. The median follow-up of all 48 patients was 13.7 months (range 2.5–105.9 months).

Results

At the time of analysis, 45 of 48 patients (93.8%) had disease recurrences, and the lung was the most frequent site for recurrence (37 patients). In multivariate analysis, performance status (PS) and number of tumours were significant predictors of lung-metastasis-free (LMF) rate. For patients with multifocal tumours, chemotherapy use significantly decreased the LMF rate (p=0.0072). The 2-year actuarial overall survival (OS), progression-free survival and local control rates in all 48 patients were 22.1%, 10.7% and 46.3%, respectively. In multivariate analysis, PS, number of tumours, surgery and radiotherapy were significant prognostic factors for OS. Patients treated with both surgery and radiotherapy (2-year OS: 45.8%) had a significantly more favourable OS (p<0.0001) than patients treated with either surgery or radiotherapy (2-year OS: 11.1%) and patients treated with neither surgery nor radiotherapy (2-year OS: 0%).

Conclusions

Our results indicated that PS and number of tumours were significant predictors for developing lung metastases. Our results also indicated that PS, number of tumours, surgery use and radiotherapy use were independent prognostic factors for OS. Multimodal treatments including surgery and radiotherapy were effective in improving OS for patients with these tumours.

Advances in knowledge

Multimodal treatments including surgery and radiotherapy are effective in improving overall survival for patients with angiosarcoma of the scalp and face.Angiosarcomas are rare malignant vascular tumours, which account for approximately 2% of all soft tissue sarcomas. Cutaneous angiosarcomas can occur as lesions in any part of the body, but most frequently arise on the scalp and face of elderly people [1,2]. Several investigators have suggested that angiosarcomas of the scalp and face form a distinctive subgroup due to their extremely poor prognosis, with 5-year survival of only 10–15% [1-3]. This highly aggressive tumour spreads widely through the skin, recurs locally and metastasises early. It is well known that this tumour frequently metastasises to the lung, often inducing repeated pneumothorax and/or haemothorax as a result of rupture of enlarged cystic tumours arising in the peripheral lung field [4,5].Although previous reports have emphasised the poor prognosis of this disease, effective treatment strategies have yet to be elucidated. Surgery was the mainstay of treatment, but the high frequency of local recurrence of this strategy is discouraging [1,2]. Radiotherapy was generally performed in cases of widely spread and unresectable tumours, but the outcomes were also unsatisfactory [1,3]. Therefore, several authors advocated a combination of surgery and radiotherapy for these tumours [3,6,7]. Recently, chemotherapy and immunotherapy using recombinant interleukin-2 (rIL-2) have been studied as potential treatments [8,9]. However, the optimal treatment for these tumours has not been clearly established.In the current study, we retrospectively analysed the results of different treatment modalities for clinically localised angiosarcoma of the scalp and face, and investigated the optimal management for these tumours.     

Graves' ophthalmopathy: the role of diffusion-weighted imaging in detecting involvement of extraocular muscles in early period of disease

Objective:

To evaluate involvement of the extraocular muscle (EOM) using diffusion-weighted imaging (DWI), to determine whether there is correlation with conventional orbital MRI and apparent diffusion coefficient (ADC) values in patients with Graves'' ophthalmopathy (GO).

Methods:

35 patients known clinically with GO and 21 healthy controls were studied. Patients were assessed with clinical activity scores. All subjects underwent conventional MRI and DWI study. Involvement of the EOM was evaluated. The patients were classified as involved or uninvolved on orbital MRI and their ADC values in DWI compared.

Results:

There was significant difference in the mean ADC value of all the EOMs in patients vs controls. The ADC values of all the EOMs were higher in patients. There were significant differences in ADC values between uninvolved muscles on conventional MRI and controls for the MR, SR and LR. There was no significant difference in ADC value between the two groups when considering the IR. ADC values of medial, lateral and superior rectus muscles were increased.

Conclusion:

Increased ADC values of the EOM in patients with GO suggest that EOM damage begins at a very early stage before being detected on routine orbital MRI. The routine MRI with DWI sequence will be a useful adjunct in the selection of a group of patients most likely to benefit from early treatment.

Advances in knowledge:

This study can help to evaluate the involvement of GO in early period with MRI added DWI.Graves'' ophthalmopathy (GO) is a disorder frequently associated with autoimmune thyroid diseases that involve the retro-ocular space. This disease leads to oedema and swelling resulting in proptosis and diplopia.^1,2 It is clinically relevant in 40–50% of patients with Graves'' disease and in 2–5% of patients with immune thyroiditis.³GO is usually bilateral, but it can be asymmetric or unilateral in 15% of patients.³ The exact pathogenesis of GO remains unclear. Whatever the mechanism, ultimately, the connective tissues are extensively remodelled with the enlargement of the extraocular muscles (EOMs) and orbital adipose tissues.^4,5 Patients with GO usually present symmetric, multiple EOM enlargement in both orbits, although asymmetric muscle involvement can occur. However, true unilateral orbital involvement is uncommon, occurring in only 6–10% of patients.⁶ The muscles most frequently affected are the medial and inferior rectus muscles.⁶Orbital conventional MRI is required to avoid unnecessary decompression surgery in unclear or asymmetric proptosis, in suspected optic neuropathy. MRI can detect not only the presence or absence of swollen tissue but also objectively quantify the activity of inflammation.⁷ Diffusion-weighted imaging (DWI) provides qualitative and quantitative functional information concerning the microscopic movements of water at the cellular level. It allows a non-invasive characterization of microstructural changes. DWI has become a valuable imaging method in the evaluation of certain diseases such as head and neck, liver or kidney lesions.Recently, there has been one study on evaluation of GO using MRI with DWI in literature.⁸ The goal of our study was to assess whether differences between involvement on conventional orbital MRI and apparent diffusion coefficient (ADC) values for each EOM in patients with GO compared with those in healthy controls, and to investigate effectiveness of ADC values in diagnosis of involvement of EOM.     

Averaging improves strain images of the biceps brachii using quasi-static ultrasound elastography

Objective:

Quasi-static ultrasound elastography is a technique for measuring tissue deformation (strain) under externally applied loading and can be used to identify the presence of abnormalities. The objective of this study was to demonstrate the efficacy of averaging strain images from repeated compression cycles in mitigating user-induced error using quasi-static ultrasound elastography.

Methods:

Freehand compressions were performed with an ultrasound transducer on the biceps brachii of nine participants (five males and four females), as well as with a custom automated compression system. Sets of strain images from the freehand techniques were averaged to create single representative images and compared against strain images from the automated compressions using both qualitative and quantitative metrics.

Results:

Significant improvements in intra-operator repeatability and interoperator reproducibility can be achieved by averaging strain images from four to eight repeated compressions. The resulting strain images did not lose significant image data compared with strain images from single automated compressions.

Conclusion:

Averaging is introduced as a feasible and appropriate technique to improve strain image quality without sacrificing important image data.

Advances in knowledge:

Simple averaging of multiple freehand elastography measures can achieve a similar degree of accuracy, repeatability and reproducibility as that of more awkward and expensive automated methods. The resulting elastograms can be used to obtain a more accurate and complete diagnosis without additional cost to the doctor or the patient.Damage to the skeletal muscle tissue, such as contusions, tears and strains, accounts for approximately 90% of all sport-related injuries.¹ Although MRI is currently the gold standard for diagnostic imaging of soft tissue, ultrasound is recognized as a viable alternative for soft-tissue imaging, owing to its portability, affordability and ability to capture sequences of images in real time.^2,3 Quasi-static elastography (QSE) takes advantage of the unique ability of ultrasound to capture image sequences to track tissue deformation and has emerged as a potential diagnostic tool to monitor musculoskeletal pathologies.⁴QSE operates on the principle that when tissue is externally compressed, the resulting deformation depends on the mechanical properties of the tissue.⁵ Accordingly, this technique tries to recover information about the mechanical properties from the information about tissue deformation. Ultrasound elastography has been shown to detect lesions in the breast tissue and fibrosis in the liver tissue^6–9 and to measure intravascular elasticity,^10,11 as well as an ability to estimate strain in tendons.^12–14 QSE could also potentially be used to identify regions of damaged or abnormal tissue in skeletal muscles, but there are few studies exploring these applications.⁴The primary limitation of QSE is its dependence on consistent and steady ultrasound images to create quality strain images. Image steadiness is particularly important with musculoskeletal tissues owing to their anisotropic and inhomogeneous structure. Variability in image collection, inherent to the nature of freehand manipulation of the ultrasound transducer, results in changes in the imaging window and unsteady application of force during a single compression, as well as variations in the rate, magnitude and direction of loading between trials. These inconsistencies may lead to large errors in the resulting strain images, directly affecting the accuracy and repeatability of strain measurements. For example, transducer misalignment alone has been shown to result in strain measurement errors as high as 23%.¹⁵ To mitigate variation between examinations and measurement error, a number of studies have developed scanning systems that assist the operator while examining the tissue of interest. These automated and assisted systems have employed various mechanical compression and feedback techniques to successfully reduce extraneous transducer motion and improve the resulting strain images.^16–18 However, these enhancements do come at the cost of added training and expensive, often cumbersome equipment.Rather than attempting to eliminate the aforementioned sources of measurement error themselves, it may be possible to minimize the imprecision of the strain images through a simple averaging procedure, wherein multiple ultrasound compression scans are performed, and the resulting strain images averaged to create a single representative image.Although averaging is expected to improve repeatability in the strain images, currently, there is no literature employing such averaging techniques to musculoskeletal elastography. Instead, multiple compressions are performed, and the result of a single scan is selected from amongst the set to be further analysed.^13,14,19 Several questions about the approach of averaging need to be addressed, including (1) can it achieve similar strain image repeatability as automated scans? (2) Does it require too many scans to achieve acceptable repeatability? (3) Will averaging actually remove important data in the image that are unique to the patient and are needed to properly characterize the tissue health?In this article, we determine whether averaging strain images from repeated scans of the biceps brachii reduces the effects of variability in ultrasound images. Specifically, we tested three hypotheses: (1) the final images created by averaging strain images over multiple manual scans are both qualitatively and quantitatively similar to strain images resulting from automated compression procedures; (2) averaging over multiple scans increases the repeatability of the resulting strain images compared with that of single automated compressions; and (3) the averaged strain images from a single subject will be more reproducible between operators than strain images from a single freehand scan.     

Contrast-enhanced ultrasound of intrahepatic cholangiocarcinoma: correlation with pathological examination

Objective

To investigate the correlation between enhancement patterns of intrahepatic cholangiocarcinoma (ICC) on contrast-enhanced ultrasound (CEUS) and pathological findings.

Methods

The CEUS enhancement patterns of 40 pathologically proven ICC lesions were retrospectively analysed. Pathologically, the degree of tumour cell and fibrosis distribution in the lesion was semi-quantitatively evaluated.

Results

4 enhancement patterns were observed in the arterial phase for 32 mass-forming ICCs: peripheral rim-like hyperenhancement (n=19); heterogeneous hyperenhancement (n=6); homogeneous hyperenhancement (n=3); and heterogeneous hypo-enhancement (n=4). Among the four enhancement patterns, the differences in tumour cell distribution were statistically significant (p<0.05). The hyperenhancing area on CEUS corresponded to more tumour cells for mass-forming ICCs. Heterogeneous hyperenhancement (n=2) and heterogeneous hypo-enhancement (n=2) were observed in the arterial phase for four periductal infiltrating ICCs. In this subtype, fibrosis was more commonly found in the lesions. Heterogeneous hyperenhancement (n=1) and homogeneous hyperenhancement (n=3) were observed in the arterial phase for four intraductal growing ICCs. This subtype tended to have abundant tumour cells.

Conclusion

The CEUS findings of ICC relate to the degree of carcinoma cell proliferation at pathological examination. Hyperenhancing areas in the tumour always indicated increased density of cancer cells.Intrahepatic cholangiocarcinoma (ICC) originates in the small bile duct and is grouped according to the International Classification of Diseases code, with hepatocellular carcinoma (HCC) being the primary liver tumour. It is the second most common primary liver tumour and is highly malignant. Although ICC is a relatively rare tumour, interest in this disease is rising because incidence and mortality rates for ICC are increasing steadily worldwide [1-5].ICC is notoriously difficult to diagnose and is usually fatal, owing to its late clinical presentation and the lack of effective non-surgical therapeutic modalities. It tends to present with non-specific symptoms such as malaise, weight loss and abdominal pain. Most patients have unresectable disease at presentation and die within 12 months from the effects of cancer cachexia and a subsequent rapid decline in performance status.According to growth characteristics, ICC is subcategorised into mass-forming, periductal infiltrating or intraductal-growing types by the Liver Cancer Study Group of Japan [6]. These subtypes show different biological behaviours and have different clinical outcomes. Mass-forming ICC spreads between hepatocyte plates and expands via the hepatic sinusoidal spaces. It often invades the adjacent peripheral branches of the portal vein. Periductal-infiltrating ICC tends to spread along the bile duct wall via the nerve and perineural tissue of Glisson''s capsule towards the porta hepatis. Intraductal-growing ICCs are usually small or polypoid and do not invade deeply into the submucosal layer, often spreading superficially along the mucosa surface. Characterisation of the tumours in terms of their growth pattern is necessary for optimal treatment planning and prognosis assessing. The prognosis for mass-forming and periductal-infiltrating cholangiocarcinoma is generally unfavourable, but is much better for the intraductal-growing type after surgical resection, and long-term patient survival can be expected [7,8].Contrast-enhanced ultrasound (CEUS) has been increasingly applied in liver imaging. By administration of ultrasound contrast agents, CEUS can display dynamic blood flow perfusion and microcirculation of liver lesions [9], similar to CT and MRI. In previous studies, CEUS had a similar diagnostic accuracy for ICC to CT and was suggested as an alternative diagnostic option when CT examination was not available for patients with iodine allergy or impaired renal function [10]. It was confirmed that CT and/or MRI findings of ICC were correlated with pathological findings; that is, the hyperenhancing areas always indicated a large number of tumour cells and the areas of delayed enhancement corresponded to fibrotic stroma at pathological examination. In addition, different morphological subtypes tended to exhibit distinct enhancement characteristics on CT [7,8,11-13]. On CEUS, besides the specific feature of peripheral rim-like hyperenhancement, diverse imaging findings of ICC were reported [9,10,14-17]. These different CEUS appearances may reflect the differences in pathological subtypes or components of ICC. The aim of this study was to investigate the correlation between the enhancement pattern of ICC on CEUS and pathological findings. This information may be useful for diagnosis, treatment planning and prognostic evaluation of ICC.     

MRI of the anatomical structures of the knee: the proton density-weighted fast spin-echo sequence vs the proton density-weighted fast-recovery fast spin-echo sequence

Objective

The purpose of this study was to compare the proton-density (PD)-weighted fast spin-echo (FSE) and fast-recovery FSE (FRFSE) sequences for the evaluation of the anatomical structures of the knee.

Method

24 healthy volunteers who underwent MRI by both sagittal PD-weighted FSE and FRFSE sequences were evaluated. The signal-to-noise ratio, contrast-to-noise ratio (CNR) and anatomical detail visualisation were compared for the two techniques.

Results

The mean CNRs and reader ratings for both readers were significantly higher for the PD-weighted FRFSE images than for the PD-weighted FSE images in the cartilages/the femorotibial joint effusion and the cruciate ligaments/the effusion around the cruciate ligaments; however, the mean CNRs and reader ratings for both readers were significantly higher for the PD-weighted FSE sequences than for the PD-weighted FRFSE sequences in the cartilages/the menisci and the cruciate ligaments.

Conclusions

The main advantages of the PD-weighted FRFSE sequence are the increase in contrast between fluid and non-fluid tissues and the time saved by using the procedure. However, in the absence of joint effusion, the PD-weighted FRFSE sequence generates a poorer contrast between the cartilage and meniscus, the cruciate ligaments and fat of the intercondylar fossa.MRI of the knee is traditionally done with multiple two-dimensional (2D) multislice acquisitions. Fast spin-echo (FSE) is commonly used to provide proton-density (PD) or T₂ weighted images in a reasonable scanning time. These images are useful to look for internal derangements such as meniscal tears [1,2], ligamentous injury [3] or cartilage damage [4,5].2D FSE has limitations in examinations of the knee. The voxels are not isotropic, with relatively thick slices compared with the in-plane resolution, leading to partial volume artefacts. In addition, because of the anisotropic nature of the voxels, these images do not lend themselves to reformations. Magnetisation transfer due to slice selection can decrease the signal in cartilage or muscle [6]. Finally, slice gaps do not permit accurate quantification of structures such as cartilage volume.Using isotropic three-dimensional (3D) T₂ or PD-weighted techniques may solve these problems and potentially optimise visualisation of knee abnormalities [7,8]. Isotropic voxels would allow reformations with different slice thicknesses in any imaging plane, reducing the imaging time by eliminating the need to acquire sequences in multiple imaging planes. The 3D FSE techniques were developed by several investigators. Mugler [9] and Park et al [10] first described a 3D FSE sequence with variable flip angles and long echo trains and established the technique for brain imaging. Subsequently, a new fast-recovery 3D FSE sequence with a longer echo train acquisition [3D XETA (eXtended Echo Train Acquisition)] was developed by Busse et al [11] for knee imaging and was evaluated by Gold et al [7] to optimise the echo time (TE) and echo train length (ETL) as well as to improve scanning efficiency. This sequence allowed acquisition of T₂ or PD-weighted 3D FSE images with isotropic resolution within an acceptable data acquisition time with minimal blurring for clinical knee MRI at 1.5 T.Certainly, the 3D FSE sequence is an excellent technique for evaluation of the knee, especially in terms of avoiding the partial volume artefacts and magnetisation transfer effects. However, it is difficult to completely replace the 2D FSE sequence with the 3D one. Because the 3D FSE sequence requires long acquisition times, there is an increased opportunity for patient motion. Owing to this constraint, shorter 2D sequences are often preferred, although they do not permit the free 3D multiplanar reformatting without loss of image quality in the three major anatomical planes that 3D sequences provide.2D fast-recovery FSE (FRFSE) was developed to increase the fluid signal in short repetition time (TR) imaging [12]. This sequence, similar to driven-equilibrium imaging [12-15], tips magnetisation back to the z-axis after each TR. Otherwise, this sequence has limitations similar to 2D FSE with respect to anisotropic voxels and magnetisation transfer effects [7]. This technique can be used either for T₂ weighted imaging (long TEs) with relatively short TRs or for T₁ like imaging (short TEs) with an artificially increased signal intensity of free water. However, no investigator has explored the performance of the 2D PD-weighted FRFSE sequence for the evaluation of the knee.The purpose of this study was to compare the 2D PD-weighted FSE sequence with the 2D PD-weighted FRFSE sequence for the evaluation of the knee. For technical assessment and visualisation of anatomical structures, a volunteer study was conducted. Technical assessment included a comparison of the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) of relevant anatomical structures. Furthermore, the visualisation of anatomical details of both sequences was compared.