Imaging appearances for recurrent nasopharyngeal carcinoma and post-salvage nasopharyngectomy

Nasopharyngeal carcinoma (NPC) is a head and neck neoplasm that occurs in endemic numbers among people of southern Chinese descent. External beam radiation to the nasopharyngeal bed and primary draining lymph node echelons is the mainstay of treatment with concurrent cisplatin-based chemotherapy for more advanced disease. Detection of residual and/or recurrent NPC has important clinical implications, as salvage protocols are available. The review aims to increase awareness of the imaging features of NPC recurrences at local and distant sites using computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET). Important changes in imaging seen in patients after nasopharyngectomy are also discussed.

The role of chest ultrasonography in the management of respiratory diseases: document II

Chest ultrasonography can be a useful diagnostic tool for respiratory physicians. It can be used to complete and widen the general objective examination also in emergency situations, at the patient's bedside. The aim of this document is to promote better knowledge and more widespread use of thoracic ultrasound among respiratory physicians in Italy.This document II is focused on advanced approaches to chest ultrasonography especially in diagnosing sonographic interstitial syndrome with physical hypotheses about the genesis of vertical artifacts, differential diagnosis of cardiogenic pulmonary edema and non-cardiogenic pulmonary edema, raising diagnostic suspicion of pulmonary embolism, ultrasound characterization of lung consolidations and the use of ultrasonography to guide procedural interventions in pulmonology.Finally, document II focuses on chest ultrasonography as useful diagnostic tool in neonatal and pediatric care.

Normal breast tissue stiffness measured by a new ultrasound technique: virtual touch tissue imaging quantification (VTIQ)

OBJECTIVE

To evaluate normal breast tissue stiffness with virtual touch tissue imaging quantification (VTIQ) using prospectively collected data.

MATERIALS AND METHODS

B-mode ultrasound and VTIQ were performed in 132 breasts in 97 women. Mean values of VTIQ for parenchyma and fatty tissue were compared between those measured in healthy breasts and in the surrounding of histologically proven benign and malignant breast lesions. Moreover we reviewed VTIQ values according to breast density measured by the American College of Radiology (ACR) categories. In addition we analyzed re-test reliability of VTIQ.

RESULTS

In 132 breasts the mean VTIQ values in parenchyma were significantly higher than in fatty tissue (3.23 m/s ± 0.74 versus 2.5 m/s ± 0.61; p<0.0001). In healthy breasts as well as in the surrounding of a benign or malignant lesions the VTIQ values of parenchyma were similar (p=0.12). In fatty tissue, small differences between mean VTIQ values of 2.25 m/s ± 0.51, 2.52 m/s ± 0.48 and 2.65 m/s ± 0.71 (p=0.01) in the respective groups were observed. The comparison of mean VTIQ values of parenchyma and fatty tissue in more and less dense breasts (ACR 1+2 versus ACR 3+4 breasts) also yielded no statistically significant difference. The re-test reliability of VTIQ assessed with three independent measurements was moderate (interclass-correlation of 0.52 (p<0.0001)).

CONCLUSION

VTIQ is a reliable method for measuring the stiffness of breast tissue. We propose standard values for healthy parenchyma and fatty tissues independent of the surrounding tissue or the ACR category.

Contrast-enhanced ultrasound in the preoperative, intraoperative and postoperative assessment of liver lesions

The use of contrast agents (CA) with liver ultrasound (US) has gained recently an established role for the diagnosis of various hepatic diseases due to their safety, high versatility and low costs (contrast-enhanced ultrasound: CEUS). The purpose of this review is to provide a state-of-the-art summary of the available evidence for their use in the characterization of focal liver lesions. A published work search was conducted for all preclinical and clinical studies involving CA on hepatic US imaging. CEUS increases the sensitivity for lesion detection and the specificity to differentiate between benign and malignant diseases due to the enhanced visualization of the tumor microcirculation. Results achieved seem at least equivalent to those of spiral computed tomography or magnetic resonance imaging. The association of CA with intraoperative ultrasound has changed the surgical approach in 25% of patients and guarantees complete ablations by a single session in most of them. CEUS provides detailed information about tumor vasculature, improves the preoperative characterization and therefore the therapeutic strategy, and can evaluate the intraoperative completeness of the ablation.

Reproducibility of brain spectroscopy at 7T using conventional localization and spectral editing techniques

PURPOSE

To evaluate the reproducibility of spectroscopic measurements from the anterior cingulate (AC) and the dorsolateral prefrontal cortex (DLPFC) regions at 7T using a 32-channel head coil.

MATERIALS AND METHODS

Spectra were acquired in four healthy subjects each scanned twice using a stimulated echo acquisition mode (STEAM) sequence, and a MEGA-PRESS-IVS sequence for gamma-aminobutyric acid (GABA) editing. STEAM spectra were quantified using LCModel, whereas MEGA-PRESS-IVS data were analyzed using peak integrals determined using in-house software. Mean coefficient of variation (CV) and mean absolute difference between visits were calculated.

RESULTS

For the AC STEAM dataset, the mean CV between visits was 6.2% for prominent metabolites such as N-acetylaspartate (NAA), total creatine (tCr), and total choline (tCho) and 6.3% for low signal-to-noise ratio (SNR) metabolites such as glutamate (Glu), glutamine (Gln), and GABA. The mean CV between visits for the DLPFC STEAM dataset was 8.5% for prominent metabolites and 21% for lower SNR metabolites. In the AC, the reproducibility measures for GABA were superior for STEAM compared to MEGA-PRESS-IVS (mean CV of 3.5% vs. 13.6%), but the opposite pattern was observed in the DLPFC region (mean CV of 16.2% vs. 13.4%).

CONCLUSION

7T MR spectroscopy of the AC and DLPFC using both short TE STEAM and MEGA-PRESS-IVS sequences provide excellent reproducibility of 12 metabolites, including GABA.

Spectral Doppler sonography: a noninvasive method for predicting dyspermia

OBJECTIVES

Sonography is a noninvasive, office-based diagnostic tool often used for evaluation of subfertile men. Previous studies have suggested that a resistive index (RI) greater than 0.6 is associated with impaired spermatogenesis. We sought to validate this threshold in a urologic patient population presenting for infertility evaluation.

METHODS

We retrospectively reviewed 99 consecutive patients seen for nonobstructive male infertility at our institution. Patient demographics, semen analysis parameters, hormone profiles, lipid profiles, and penile and scrotal sonographic measurements were recorded. The RI was calculated from measurements of the peak systolic velocity and end-diastolic velocity. Ninety-one patients fit the inclusion criteria and were subsequently divided into 2 groups based on RI: group 1 with RI values of 0.6 or less (n = 49) and group 2 with RI values greater than 0.6 (n = 42).

RESULTS

Variables that were significantly different between the groups included age, total sperm count, percent motile sperm, total motile sperm, follicle-stimulating hormone, high-density lipoprotein, and testis volume. On the other hand, body mass index, forward progression, World Health Organization score, total testosterone, free testosterone, estradiol, total cholesterol, low-density lipoprotein, and triglycerides were not significantly different between the groups. A receiver operating characteristic curve revealed an area under the curve of 0.64 (confidence interval, 0.52-0.75; P = .025). At the threshold of greater than 0.6, the RI had specificity of 63.27% and a 1.56 likelihood ratio to predict total motile sperm less than 20 × 10(6) at spermatogenesis.

CONCLUSIONS

An intratesticular RI greater than 0.6 is associated with impaired spermatogenesis. This finding supports the use of testicular spectral Doppler sonography as a noninvasive tool for evaluation of testicular function.

Advanced ultrasonography technologies to assess the effects of radiofrequency ablation on hepatocellular carcinoma

Background

Radiofrequency ablation (RFA) is a curative therapy for hepatocellular carcinoma (HCC). In RFA, ultrasonography (US) is most commonly used to guide tumor puncture, while its effects are assessed using dynamic computed tomography or magnetic resonance. The differences in modalities used for RFA and assessment of its effects complicate RFA. We developed a method for assessing the effects of RFA on HCC by combining contrast-enhanced (CE) US and real-time virtual sonography with three-dimensional US data.

Patients and methods

Before RFA, we performed a sweep scan of the target HCC nodule and the surrounding hepatic parenchyma to generate three-dimensional US data. After RFA, we synchronized multi-planar reconstruction images derived from stored three-dimensional US data with real-time US images on the same US monitor and performed CEUS and real-time virtual sonography. Using a marking function, we drew a sphere marker along the target HCC nodule contour on pre-treatment US- multi-planar reconstruction images so that the automatically synchronized sphere marker represented the original HCC nodule contour on post-treatment real-time CEUS images. Ablation was considered sufficient when an avascular area with a margin of several millimeters in all directions surrounded the sphere marker on CEUS.

Results

This method was feasible and useful for assessing therapeutic effects in 13 consecutive patients with HCC who underwent RFA. In 2 patients who underwent multiple sessions of RFA, HCC-nodule portions requiring additional RFA were easily identified on US images.

Conclusions

This method using advanced US technologies will facilitate assessment of the effects of RFA on HCC.

Gene delivery to periodontal tissue using Bubble liposomes and ultrasound

BACKGROUND AND OBJECTIVE

Periodontitis is the most common inflammatory disease caused by oral biofilm infection. For efficient periodontal treatment, it is important to enhance the outcome of existing regenerative therapies. The physical action of an ultrasound may be able to deliver a therapeutic gene or drugs into the local area of the periodontium being treated for periodontal regeneration. Previously, we developed "Bubble liposomes" as a useful carrier for gene or drug delivery, and reported that delivery efficiency was increased with high-frequency ultrasound in vitro and in vivo. Hence, the aim of the present study was to examine the possibility of delivering genes into gingival tissues using Bubble liposomes and ultrasound.

MATERIAL AND METHODS

We attempted to deliver naked plasmid DNA encoding luciferase or enhanced green fluorescent protein (EGFP) into the lower labial gingiva of Wistar rats using Bubble liposomes, with or without ultrasound exposure. Ultrasound parameters were optimized for intensity (0-4.0 W/cm(2) ) and exposure time (0-120 s) to establish the most efficient conditions for exposure. The efficacy and duration of gene expression in the gingiva were investigated using a luciferase assay and fluorescence microscopy.

RESULTS

The strongest relative luciferase activity was observed when rats were treated under the following ultrasound conditions: 2.0 W/cm(2) intensity and 30 s of exposure time. Relative luciferase activity, 1 d after gene delivery, was significantly higher in gingiva treated using Bubble liposomes and ultrasound than in gingiva of the other treatment groups. Histological analysis also showed that distinct EGFP-expressing cells were observed in transfected gingiva when rats were treated under optimized conditions.

CONCLUSION

From these results, the combination of Bubble liposomes and ultrasound provides an efficient technique for delivering plasmid DNA into the gingiva. This technique can be applied for the delivery of a variety of therapeutic molecules into target tissue, and may serve as a useful treatment strategy for periodontitis.

In vivo proton range verification: a review

Protons are an interesting modality for radiotherapy because of their well defined range and favourable depth dose characteristics. On the other hand, these same characteristics lead to added uncertainties in their delivery. This is particularly the case at the distal end of proton dose distributions, where the dose gradient can be extremely steep. In practice however, this gradient is rarely used to spare critical normal tissues due to such worries about its exact position in the patient. Reasons for this uncertainty are inaccuracies and non-uniqueness of the calibration from CT Hounsfield units to proton stopping powers, imaging artefacts (e.g. due to metal implants) and anatomical changes of the patient during treatment. In order to improve the precision of proton therapy therefore, it would be extremely desirable to verify proton range in vivo, either prior to, during, or after therapy. In this review, we describe and compare state-of-the art in vivo proton range verification methods currently being proposed, developed or clinically implemented.

Tracheo-bronchial angles in the human fetus -- an anatomical, digital, and statistical study

Background

Both the advancement of visual techniques and intensive progress in perinatal medicine result in performing airway management in the fetus and neonate affected by life-threatening malformations. This study aimed to examine the 3 tracheo-bronchial angles, including the right and left bronchial angles, and the interbronchial angle, in the fetus at various gestational ages.

Material/Methods

Using methods of anatomical dissection, digital image analysis with an adequate program (NIS-Elements BR 3.0, Nikon), and statistics, values of the two bronchial angles and their sum as the interbronchial angle were semi-automatically measured in 73 human fetuses at the age of 14–25 weeks, derived from spontaneous abortions and stillbirths.

Results

No male-female differences between the parameters studied were found. The 3 fetal tracheo-bronchial angles were found to be independent of age. The right bronchial angle ranged from 11.4° to 41.8°, and averaged 26.9±7.0° for the whole analyzed sample. The values of left bronchial angle varied from 24.8° to 64.8°, with the overall mean of 46.2±8.0°. As a consequence, the interbronchial angle totalled 36.2–96.6°, and averaged 73.1±12.7°.

Conclusions

The tracheo-bronchial angles change independently of sex and fetal age. The left bronchial angle is wider than the right one. Values of the 3 tracheo-bronchial angles are unpredictable since their regression curves of best fit with relation to fetal age cannot be modelled. Both of the 2 bronchial angles and the interbronchial angle are of great relevance in the location of inhaled foreign bodies, and in the diagnosis cardiac diseases and mediastinal abnormalities.

Risk factors and classifications of hilar cholangiocarcinoma

Cholangiocarcinoma is the second most common primary malignant tumor of the liver. Perihilar cholangiocarcinoma or Klatskin tumor represents more than 50% of all biliary tract cholangiocarcinomas. A wide range of risk factors have been identified among patients with Perihilar cholangiocarcinoma including advanced age, male gender, primary sclerosing cholangitis, choledochal cysts, cholelithiasis, cholecystitis, parasitic infection (Opisthorchis viverrini and Clonorchis sinensis), inflammatory bowel disease, alcoholic cirrhosis, nonalcoholic cirrhosis, chronic pancreatitis and metabolic syndrome. Various classifications have been used to describe the pathologic and radiologic appearance of cholangiocarcinoma. The three systems most commonly used to evaluate Perihilar cholangiocarcinoma are the Bismuth-Corlette (BC) system, the Memorial Sloan-Kettering Cancer Center and the TNM classification. The BC classification provides preoperative assessment of local spread. The Memorial Sloan-Kettering cancer center proposes a staging system according to three factors related to local tumor extent: the location and extent of bile duct involvement, the presence or absence of portal venous invasion, and the presence or absence of hepatic lobar atrophy. The TNM classification, besides the usual descriptors, tumor, node and metastases, provides additional information concerning the possibility for the residual tumor (R) and the histological grade (G). Recently, in 2011, a new consensus classification for the Perihilar cholangiocarcinoma had been published. The consensus was organised by the European Hepato-Pancreato-Biliary Association which identified the need for a new staging system for this type of tumors. The classification includes information concerning biliary or vascular (portal or arterial) involvement, lymph node status or metastases, but also other essential aspects related to the surgical risk, such as remnant hepatic volume or the possibility of underlying disease.

Sources of error in emergency ultrasonography

BACKGROUND

To evaluate the common sources of diagnostic errors in emergency ultrasonography.

METHODS

The authors performed a Medline search using PubMed (National Library of Medicine, Bethesda, Maryland) for original research and review publications examining the common sources of errors in diagnosis with specific reference to emergency ultrasonography. The search design utilized different association of the following terms : (1) emergency ultrasonography, (2) error, (3) malpractice and (4) medical negligence. This review was restricted to human studies and to English-language literature. Four authors reviewed all the titles and subsequent the abstract of 171 articles that appeared appropriate. Other articles were recognized by reviewing the reference lists of significant papers. Finally, the full text of 48 selected articles was reviewed.

RESULTS

Several studies indicate that the etiology of error in emergency ultrasonography is multi-factorial. Common sources of error in emergency ultrasonography are: lack of attention to the clinical history and examination, lack of communication with the patient, lack of knowledge of the technical equipment, use of inappropriate probes, inadequate optimization of the images, failure of perception, lack of knowledge of the possible differential diagnoses, over-estimation of one's own skill, failure to suggest further ultrasound examinations or other imaging techniques.

CONCLUSIONS

To reduce errors in interpretation of ultrasonographic findings, the sonographer needs to be aware of the limitations of ultrasonography in the emergency setting, and the similarities in the appearances of various physiological and pathological processes. Adequate clinical informations are essential. Diagnostic errors should be considered not as signs of failure, but as learning opportunities.

Fusion of intravenous contrast-enhanced C-arm CT and pretreatment imaging for ablation margin assessment of liver tumors: A preliminary study

The aim of this preliminary study was to evaluate the feasibility of assessing ablation margins after radiofrequency ablation (RFA) of liver tumors from fusion images of post-treatment C-arm computed tomography (CT) images fused to pretreatment images. Five patients with liver tumors underwent RFA. Intravenous contrast-enhanced C-arm CT images were obtained for all patients immediately after RFA, and multi-detector CT (MDCT) images were obtained 3-7 days later. The C-arm CT and MDCT images were fused to pretreatment images using a multimodality image fusion software. The minimum ablation margins were assessed in the C-arm CT and MDCT fusion images. Ablation margins after RFA of liver tumors can be measured using intravenous contrast-enhanced C-arm CT images fused with pretreatment images. This technique has the potential for use in the intra-procedural assessment of liver tumor ablation.

Transarterial chemoembolization in combination with local therapies for hepatocellular carcinoma: a meta-analysis

Background

In previous randomized trials, transarterial chemoembolization (TACE) has shown an improvement of survival rate in hepatocellular carcinoma (HCC) when combined with radiofrequency ablation (RFA), percutaneous ethanol injection (PEI) or other therapies. The aim of this meta-analysis was to evaluate the effectiveness of combination therapy of TACE with RFA, PEI, radiotherapy (RT), three-dimensional conformal radiation therapy (3D-CRT) or High-Intensity Focused Ultrasound (HIFU).

Methods

Randomized or nonrandomized studies comparing TACE combined with RFA, PEI, RT, 3D-CRT or HIFU with TACE alone for HCC were included. Meta-analysis was performed using a fix-effects model in RCTs and a random-effects model among the observational studies.

Results

10 randomized trials and 18 observational studies matched the selection criteria, including 2497 patients (682 in RCTs, 1815 in non-RCTs). Meta-analysis of RCTs showed that the combination of TACE and PEI ((RR)_1-year=1.10, 95%CI=0.99-1.22, p=0.073; (RR)_3-year=2.32, 95%CI=1.52-3.53, p<0.001), TACE+RT ((RR)_1-year=1.37, 95%CI=1.11-1.70, p=0.004; (RR)_3-year=2.32, 95%CI=1.44-3.75, p=0.001) were associated with higher survival rates. The results of observational studies were in good consistency with that of RCTs. Furthermore, TACE plus 3D-CRT ((RR)_1-year=1.22, 95%CI=1.06-1.41, p=0.005; (RR)_3-year=2.05, 95%CI=1.48-2.84, p<0.001) and TACE plus HIFU ((RR)_1-year=1.16, 95%CI=1.01-1.33, p=0.033; (RR)_3-year=1.66, 95%CI=1.12-2.45, p=0.011) have introduced marked survival benefit when pooling results from observational studies.

Conclusions

This meta-analysis demonstrated that TACE combined with local treatments, especially PEI, HIFU or 3D-CRT could improve the overall survival status than performing TACE alone. Importantly, these results need to be validated in further high-quality clinical trials.

Transarterial chemoembolization in combination with local therapies for hepatocellular carcinoma: a meta-analysis

BACKGROUND

In previous randomized trials, transarterial chemoembolization (TACE) has shown an improvement of survival rate in hepatocellular carcinoma (HCC) when combined with radiofrequency ablation (RFA), percutaneous ethanol injection (PEI) or other therapies. The aim of this meta-analysis was to evaluate the effectiveness of combination therapy of TACE with RFA, PEI, radiotherapy (RT), three-dimensional conformal radiation therapy (3D-CRT) or High-Intensity Focused Ultrasound (HIFU).

METHODS

Randomized or nonrandomized studies comparing TACE combined with RFA, PEI, RT, 3D-CRT or HIFU with TACE alone for HCC were included. Meta-analysis was performed using a fix-effects model in RCTs and a random-effects model among the observational studies.

RESULTS

10 randomized trials and 18 observational studies matched the selection criteria, including 2497 patients (682 in RCTs, 1815 in non-RCTs). Meta-analysis of RCTs showed that the combination of TACE and PEI ((RR)(1-)year=1.10, 95%CI=0.99-1.22, p=0.073; (RR)(3-)year=2.32, 95%CI=1.52-3.53, p<0.001), TACE+RT ((RR)(1-)year=1.37, 95%CI=1.11-1.70, p=0.004; (RR)(3-)year=2.32, 95%CI=1.44-3.75, p=0.001) were associated with higher survival rates. The results of observational studies were in good consistency with that of RCTs. Furthermore, TACE plus 3D-CRT ((RR)1 -year=1.22, 95%CI=1.06-1.41, p=0.005; (RR)(3-)year=2.05, 95%CI=1.48-2.84, p<0.001) and TACE plus HIFU ((RR)(1-)year=1.16, 95%CI=1.01-1.33, p=0.033; (RR)(3-)year=1.66, 95%CI=1.12-2.45, p=0.011) have introduced marked survival benefit when pooling results from observational studies.

CONCLUSIONS

This meta-analysis demonstrated that TACE combined with local treatments, especially PEI, HIFU or 3D-CRT could improve the overall survival status than performing TACE alone. Importantly, these results need to be validated in further high-quality clinical trials.

Endosonography-assisted diagnosis and therapy of gastrointestinal submucosal tumors

Submucosal tumors (SMTs) are usually discovered fortuitously during routine endoscopy, including various non-neoplastic and neoplastic conditions. Endoscopic ultrasound (EUS) is considered to be the best imaging procedure to characterize SMTs and to determine the need for further treatment. In this review, the following issues will be addressed: The role of EUS in diagnosis for SMTs, tissue diagnosis for SMTs and the influence of EUS on endoscopic resection techniques for SMTs.

Hybrid method of transurethral resection of ejaculatory ducts using holmium:yttriumaluminium garnet laser on complete ejaculatory duct obstruction

A 32-year old single man presented with azoospermia and low semen volume which was noted one and half a year ago. Transrectal ultrasonography and seminal vesiculography were performed to evaluate ejaculatory duct obstruction, and transurethral resection of the ejaculatory duct was performed using a hybrid technique of holmium:yttriumaluminium garnet laser with monopolar transurethral resection to overcome the narrow prostatic urethra. To our knowledge, this is the first report on the successful outcome of a hybrid technique applied for transurethral resection of the ejaculatory duct.

A case of mucinous cystic neoplasm of the liver: description of Sonazoid-enhanced ultrasound imaging and histopathologic findings

Mucinous cystic neoplasms (MCNs) of the hepatobiliary system are rare tumors that usually arise within the liver. We encountered a 63-year-old woman with a surgically proven MCN of the liver. We first performed contrast-enhanced ultrasound imaging, and the mass was found to have the appearance of a solid tumor, showing peripheral nodular enhancement in the arterial and portal phases with persistence of enhancement. The lesion remained enhanced in the post-vascular phase (Kupffer phase). Based on these findings, we incorrectly identified the tumor as a cavernous hemangioma, despite negative findings in computed tomography and magnetic resonance imaging. In our immunohistologic analysis using anti-CD68 antibody, the antibody-positive cells were identified as macrophages. Therefore, the Sonazoid microbubbles could have been retained within these macrophages, resulting in late enhancement. These findings appear to be of key importance in accurately diagnosing MCNs and clarifying their pathophysiology.

Dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors

OBJECTIVE

The purpose of this study is to investigate the dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors.

MATERIALS AND METHODS

We reviewed dynamic MRI findings and clinical features in 15 patients who had been treated for childhood malignant solid tumors and in whom hypervascular hepatic nodules were later found on surveillance imaging by either CT or ultrasound (or both). The benign nature of the lesion was based on histologic examination or clinical and radiologic follow-up (or both).

RESULTS

Time between initial diagnosis of malignancy and detection of the hepatic nodule ranged from 4.5 to 13.5 years with the majority of the malignancies being neuroblastoma treated by high-dose chemotherapy and hematopoietic stem cell transplantation. A total of 43 nodules were detected, often multiple and small. Most of the lesions were isointense or slightly hyperintense on T2-weighted imaging and isointense or slightly hypointense on T1-weighted imaging. All nodules had intense enhancement on the arterial phase and were isointense or slightly hyperintense on the delayed phase. A central scar was seen in four. Additionally, hepatic hemosiderosis was noted in four patients, in whom all the lesions were hyperintense on both T1- and T2-weighted imaging.

CONCLUSION

Benign hypervascular hepatic nodules in survivors of childhood malignancy occur years after high-dose chemotherapy and hematopoietic stem cell transplantation. Dynamic MRI findings including intense arterial enhancement and absence of washout in the delayed phase are of great value in the differential diagnosis of these hepatic nodules.

Contrast ultrasound in hepatocellular carcinoma at a tertiary liver center: First Indian experience

AIM: To assess the role of contrast enhanced ultrasonography in evaluation of hepatocellular carcinoma (HCC) at the first Indian tertiary liver center.

METHODS: Retrospective analysis of contrast enhanced ultrasound (CEUS) examinations over 24 mo for diagnosis, surveillance, characterization and follow up of 50 patients in the context of HCC was performed. The source and indication of referrals, change in referral rate, accuracy and usefulness of CEUS in a tertiary liver center equipped with a 64 slice dual energy computer tomography (CT) and 3 tesla magnetic resonance imaging (MRI) were studied. Sonovue (BR1, Bracco, Italy, a second generation contrast agent) was used for contrast US studies. Contrast enhanced CT/MRI or both were performed in all patients. The findings were taken as a baseline reference and correlation was done with respect to contrast US. Contrast enhanced MRI was performed using hepatocyte specific gadobenate dimeglumine (Gd-BOPTA). Iomeron (400 mg; w/v) was used for dynamic CT examinations.

RESULTS: About 20 (40%) of the examinations were referred from clinicians for characterization of a mass from previous imaging. About 15 (30%) were performed for surveillance in chronic liver disease; 5 (10%) examinations were performed for monitoring lesions after radiofrequency ablation (RFA); 3 (6%) were post trans-arterial chemo-embolization (TACE) assessments and 3 (6%) were patients with h/o iodinated contrast allergy. About 2 (4%) were performed on hemodynamically unstable patients in the intensive care with raised alpha fetoprotein and 2 (4%) patients were claustrophobic. The number of patients referred from clinicians steadily increased from 12 in the first 12 mo of the study to 38 in the last 12 mo. CEUS was able to diagnose 88% of positive cases of HCC as per reference standards. In the surveillance group, specificity was 53.3% vs 100% by CT/MRI. Post RFA and TACE specificity of lesion characterization by CEUS was 100% in single/large mass assessment, similar to CT/MRI. For non HCC lesions such as regenerative and dysplastic nodules, the specificity was 50% vs 90% by CT/MRI. The positive role of CEUS in imaging spectrum of HCC included a provisional urgent diagnosis of an incidentally detected mass. It further led to a decrease in time for further management. A confident diagnosis on CEUS was possible in cases of characterization of an indeterminate mass, in situations where the patient was unfit for CT/MRI, was allergic to iodinated contrast or had claustrophobia, etc. CEUS was also cost effective, radiation free and an easy modality for monitoring post RFA or TACE lesions.

CONCLUSION: CEUS is a valuable augmentation to the practice of ultrasonography, and an irreplaceable modality for confounding cases and interpretation of indeterminate lesions in imaging of HCC.

Malpractice claims related to musculoskeletal imaging. Incidence and anatomical location of lesions

PURPOSE

Failure to detect lesions of the musculoskeletal system is a frequent cause of malpractice claims against radiologists.

MATERIALS AND METHODS

We examined all the malpractice claims related to alleged errors in musculoskeletal imaging filed against Italian radiologists over a period of 14 years (1993-2006).

RESULTS

During the period considered, a total of 416 claims for alleged diagnostic errors relating to the musculoskeletal system were filed against radiologists; of these, 389 (93.5%) concerned failure to report fractures, and 15 (3.6%) failure to diagnose a tumour.

CONCLUSIONS

Incorrect interpretation of bone pathology is among the most common causes of litigation against radiologists; alone, it accounts for 36.4% of all malpractice claims filed during the observation period. Awareness of this risk should encourage extreme caution and diligence.

Polyphenols from the mangosteen (Garcinia mangostana) fruit for breast and prostate cancer

The mangosteen (Garcinia mangostana) is a tropical fruit native to Southeast Asia and has long been reported to contain multiple health promoting properties. This fruit is an abundant source of xanthones, a class of polyphenolic compounds with a distinctive tricyclic aromatic ring system and is largely responsible for its biological activities including anti-cancer activity. Herein we describe the anti-cancer activity and mechanisms of mangosteen polyphenolic xanthones including α-Mangostin against breast cancer and prostate cancer. So far, extracts and individual xanthones have been found to induce apoptosis and inhibit proliferation on cancer cells in vitro and in vivo. Based on the reported findings there is clear evidence that these polyphenols target multiple signaling pathways involved in cell cycle modulation and apoptosis. Further work is required to understand its potential for health promotion and potential drug discovery for prostate and breast cancer chemoprevention.

Cerebral air embolism following pigtail catheter insertion for pleural fluid drainage

Pigtail catheter drainage is a common procedure for the treatment of pleural effusion and pneumothorax. The most common complications of pigtail catheter insertion are pneumothorax, hemorrhage and chest pains. Cerebral air embolism is rare, but often fatal. In this paper, we report a case of cerebral air embolism in association with the insertion of a pigtail catheter for the drainage of a pleural effusion. A 67-year-old man is being presented with dyspnea, cough and right-side chest pains and was administered antibiotics for the treatment of pneumonia. The pneumonia failed to resolve and a loculated parapneumonic pleural effusion developed. A pigtail catheter was inserted in order to drain the pleural effusion, which resulted in cerebral air embolism. The patient was administered high-flow oxygen therapy and recovered without any neurologic complications.

Contrast-enhanced high-frequency ultrasound imaging of early stage liver metastasis in a preclinical mouse model

Monitoring angiogenesis is potentially an effective strategy for the early detection of cancer. In this study, early detection was achieved by evaluating blood vessel density in the liver using a three-dimensional contrast-enhanced high-frequency ultrasound (CE-HFUS) system and Sonazoid microbubbles. Three-dimensional CE-HFUS detected an increase in blood vessel density in the liver after intrasplenic injection of breast tumor cells into mice. The results were in agreement with immunohistochemical analysis of blood vessel density. Three-dimensional CE-HFUS using microbubbles is an attractive, novel approach for the early detection of liver metastases through quantification of new, pathological vascular growth (i.e. tumor angiogenesis).

Performance of multiparametric magnetic resonance imaging in the evaluation and management of clinically low-risk prostate cancer

OBJECTIVE

The purpose of this article is to review the multiparametric magnetic resonance imaging (mMRI) of the prostate and MR-guided prostate biopsy, and their role in the evaluation and management of men with low-risk prostate cancer.

METHODS

We performed a literature review based on the MEDLINE database search for publications on the role of mMRI (a) in detection and localization of prostate cancer, prediction of tumor aggressiveness and progression and (b) in guiding targeted prostate biopsy.

RESULTS

The mMRI, particularly diffusion-weighted imaging with T2-weighted imaging, is a useful tool for tumor localization in low-risk prostate cancer as it can detect lesions that are more likely missed on extended biopsy schemes and can identify clinically significant disease requiring definitive treatment. The MR-guided biopsy of the most suspicious lesions enables more accurate and safer approach to guide enrollment into the active surveillance program. However, the MR-guided biopsy is complex. The fusion of MRI data with transrectal ultrasound for the purpose of biopsy provides a more feasible technique with documented accurate sampling.

CONCLUSION

Although the mMRI is not routinely used for risk stratification and prognostic assessment in prostate cancer, it can provide valuable information to guide management of men with low-risk disease. Incorporation of mMRI into the workup and monitoring of patients with low-risk prostate cancer can help discriminate clinically significant disease from indolent disease. Targeted biopsy of MR-suspicious lesions enables accurate sampling of potentially aggressive tumors that may affect outcomes.

Clinical role of contrast-enhanced harmonic endoscopic ultrasound in differentiating solid lesions of the pancreas: a single-center experience in Korea

Background/Aims

The differential diagnosis of pancreatic solid lesions remains challenging. The aim of this study was to investigate the accuracy of contrast-enhanced harmonic endoscopic ultrasound (CEH-EUS) in differentiating pancreatic cancer from benign lesions.

Methods

We prospectively evaluated 37 patients with pancreatic solid lesions. After intravenous injection of a contrast agent (SonoVue), CEH-EUS was performed using a radial echoendoscope. Pancreatic solid lesions were classified into three vascular patterns (hyperintense, isointense, and hypointense) on the basis of CEH-EUS imaging, and these patterns were compared to the histological diagnosis.

Results

The lesions were hypervascular (n=6), isovascular (n=3), or hypovascular (n=28). Histological diagnosis was confirmed by EUS-FNA in 26 patients (22 adenocarcinomas, two focal pancreatitis, one pancreatic neuroendocrine tumor [NET], and one pancreatic tuberculosis); by surgery in 10 patients (four adenocarcinomas, three pancreatic NETs, two invasive intraductal papillary mucinous neoplasms, and one acinar cell carcinoma); and by both methods in one patient. Among pancreatic carcinomas, 28 out of 30 lesions (93%) had persistent hypovascular signals in the early and late phase, which indicates a sensitivity and diagnostic accuracy of 93% and 92%, respectively for the diagnosis of pancreatic cancer.

Conclusions

CEH-EUS was useful for characterization of pancreatic solid masses with high sensitivity and accuracy.

Stress-induced cardiomyopathy complicating a stroke caused by an air embolism

Systemic air embolism is a very rare (<0.1%) complication of computed tomography-guided transthoracic needle aspiration and can result in serious neurological and/or cardiac sequelae. Stroke and stress cardiomyopathy can have a variety of etiologies; however, an association of Takotsubo cardiomyopathy with cerebrovascular events precipitated by an air embolus has not been reported. We report a patient with stress-induced cardiomyopathy after an air embolus-induced stroke. The patient was managed with hyperbaric oxygenation and her cardiomyopathy was initially treated as per the acute coronary syndrome protocol until coronary angiography confirmed patent arteries. We review the pathophysiology and management recommendations for both events. Prompt recognition of air embolism-induced cerebrovascular events and stress cardiomyopathy by clinicians is imperative to the timely initiation of appropriate management and a successful treatment outcome.

Serum vascular endothelial growth factor-C levels: A possible diagnostic marker for lymph node metastasis in patients with primary non-small cell lung cancer

Accurate tumor staging is essential for selecting the appropriate treatment strategy for lung cancer. Computed tomography (CT), or positron emission tomography (PET), is the most commonly used non-invasive staging method of lymph node (LN) metastases (LNM), but this method remains unsatisfactory. The present study measured vascular endothelial growth factor (VEGF)-C levels in serum, tumor tissue and LNs to determine the correlation between serum VEGF-C and LNM, and also assessed the usefulness of serum VEGF-C as an additional diagnostic marker for identifying LNM. A total of 66 patients with non-small cell lung carcinoma (NSCLC) or benign tumors of the lung were included in this study, and circulating VEGF-C levels were assessed with enzyme-linked immunosorbent assays. RNA fractions extracted from the tumor tissues and LNs were subjected to quantitative polymerase chain reaction (qPCR) to assess the mRNA levels of VEGF-C. The VEGF-C levels in serum, tumor tissue and LNM were significantly higher compared with the control group (P<0.05). The VEGF-C levels of patients with LNM were significantly higher compared with those without LNM (P<0.05). The VEGF-C levels in the serum, tumor tissue and LNM were significantly correlated (P<0.05). With regard to the diagnosis of LNM using VEGF-C levels, the serum levels of VEGF-C reached a sensitivity of 65.0% and a specificity of 72.2% when a cutoff value of 655.65 pg/ml was applied. Serum VEGF-C levels may provide additional information for distinguishing between the absence and presence of LNM in patients with lung carcinoma. The evaluation of serum VEGF-C is complementary to accurate LN staging in NSCLC.

Usual and unusual neuroendocrine tumor metastases on (68)Ga-DOTANOC PET/CT: a pictorial review

Neuroendocrine tumors (NETs) are slow-growing indolent tumors that often present with metastatic disease at the outset. They commonly metastasize to lymph nodes, liver, bone, and lungs. However, metastasis to other rare sites may occur. It is important to have clear knowledge of unusual NET metastatic sites because their presence may lead to a more directed investigation. Also, it will be helpful in ruling out incidental second malignancies that might be encountered. The objective of this pictorial article was to provide an illustrative tutorial showing the clinical utility of Ga-labeled somatostatin analog [1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid]-1-NaI3-octreotide (Ga-DOTANOC) PET/CT for imaging usual and unusual metastatic sites in patients with NETs.

Reliability of a radiological grading system for dermal backflow in lymphoscintigraphy imaging

RATIONALE AND OBJECTIVES

Lymphoscintigraphy may be used for diagnosing secondary lymphedema. Dermal backflow, the presence of radiotracer in dermal lymphatics, is a key clinical feature. Although often reported as present or absent, a scale that assesses the severity of dermal backflow has been previously developed. The aim of this study was to determine the reliability of these two methods of assessment.

MATERIALS AND METHODS

Sixteen experienced nuclear medicine physicians assessed the quantity of dermal backflow of 57 lymphoscintigraphy scans using a 4-point descriptive scale that was dichotomized for secondary analysis. Each scan included images from four time points for women previously diagnosed with secondary lymphedema (n = 47) and controls (n = 5); five scans were presented twice to examine intraobserver reliability. This was further investigated as 13 physicians viewed the scans again on an Apple iPad2. The physicians rated their confidence in their scoring. Readers were blinded to clinical history.

RESULTS

Although both the 2- and 4-point scale had moderate interobserver reliability, the reliability of the 2-point scale was slightly higher (4-point: Fleiss κ = .418, standard error [SE] = .008); 2-point: Fleiss κ = .574, SE = .013). Low interobserver reliability was found when only control subjects were considered (Fleiss κ = 0.055, SE = 0.034). Intraobserver reliability of the five repeated images varied from poor to perfect (Cohen κ = .063 to 1.00), whereas moderate to substantial intraobserver reliability (Cohen's κ = .342 to .752) was found when comparing devices. The readers were highly confident of their scores.

CONCLUSIONS

Overall, moderate intraobserver and interobserver reliability was found for quantifying dermal backflow with both the 2- and 4-point scale.

Abdominal wall endometrioma: ultrasonographic features and correlation with clinical findings

BACKGROUND

The diagnosis of abdominal wall endometrioma (AWE) is often confused with other surgical conditions. Certain factors relating to knowledge of the clinical history of the disease make correct diagnosis and treatment difficult.

AIMS

To present the clinical findings and ultrasonographic (US) features of AWE with special emphasis on size-related features.

STUDY DESIGN

This study reviewed abdominal wall endometriomas during a 2-year period in the Radiology Department of Sifa University Hospital, Izmir.

METHODS

Eleven women (mean age 32.6 years) with 12 scar endometriomas (mean diameter 29.2 mm) were consecutively evaluated by US and Colour Doppler examination (CDUS) prior to surgery. Lesions were grouped into large (≥3 cm) and small nodules. Vascularisation was classified as location (central, peripheral and mixed) and severity (absent, moderately vascular and hypervascular). In each patient, the nature of pain (absent, cyclic: associated with menstruation and continuous), historical and clinical data were documented. Four patients underwent Magnetic Resonance Imaging and their findings were presented. Fisher's exact test, χ(2) test for categorical data and the unpaired T-test for continuous variables were used for statistical analysis.

RESULTS

In all the women, US of the AWE showed the presence of a solid hypoechoic mass (less echogenic than the surrounding hyperechoic fat) within the abdominal wall. There was a significant correlation between AWE sizes with repeated caesareans and the mean time between the last operation and admission to hospital (p<0.05). Large endometriomas showed increased central vascularity (p<0.05). Cyclic pain was more frequent in small lesions, whereas continuous pain was more commonly found in patients with larger lesions (p<0.05).

CONCLUSION

AWE is often misdiagnosed clinically because endometriosis may occur years after the caesarean section, the pain is often non-cyclic in nature, and there is not always a palpable tender mass. The sonographic and Doppler findings, along with proper correlation with clinical data, may substantially contribute to the correct diagnosis of endometrioma.

Unilocular anterior mandibular swelling

PURPOSE

To report a rare case of chondromyxoid fibroma, presenting as an unilocular anterior mandibular swelling, which is one of the least common tumours of bone comprising less than 1% of bone tumours and to review the differential diagnosis and literature for a better understanding of this disease as well as addressing the controversies in respect with its treatment.

MATERIALS AND METHODS

Previous reports about this lesion in literature were reviewed wherein data was recorded about the age, sex, race, location of pathology, presenting signs and symptoms, duration of pathology, size, radiographic findings, treatment and any recurrence on follow-up.

RESULTS

25 cases were studied and data compiled. Multisectional histopathological examination is advocated to differentiate it from osteosarcoma. Enucleation with or without curettage with long-term follow-up has been considered to be a satisfactory treatment modality.

CONCLUSION

The rarity of the lesion, limited data on the clinical presentation, histological dilemma and treatment options replete with controversies make it a tough predicament. A thorough understanding of the disease and treatment options is indispensable to treat such a case.

Pre-liver transplant biopsy in hepatocellular carcinoma: a potential criterion for exclusion from transplantation?

BACKGROUND

In cirrhotic patients with hepatocellular carcinoma (HCC), poor differentiation in pre-liver transplantation (LT) biopsy of the largest tumour is used as a criterion for exclusion from LT in some centres. The potential role of pre-LT biopsy at one centre was explored.

METHODS

A prospective database of patients undergoing orthotopic LT for radiologically diagnosed HCC at St James's University Hospital, Leeds during 2006-2011 was analysed.

RESULTS

A total of 60 predominantly male (85.0%) patients with viral hepatitis were identified. There were discrepancies between radiological and histopathological findings with respect to the number of tumours identified (in 27 patients, 45.0%) and their size (in 63 tumours, 64.3%). In four (6.7%) patients, the largest lesion, which would theoretically have been targeted for biopsy, was not the largest in the explant. Nine (31.0%) patients with multifocal HCC had tumours of differing grades. In two (6.9%) patients, the largest tumour was well differentiated, but smaller tumours in the explant were poorly differentiated. In one patient, the largest lesion was benign and smaller invasive tumours were confirmed histologically.

CONCLUSIONS

The need to optimize selection for LT in HCC remains. In the present series, the largest tumour was not always representative of overall tumour burden or biological aggression and its potential use to exclude patients from LT is questionable.

Human immunodeficiency virus-associated lung malignancies

This review of lung malignancies in human immunodeficiency virus (HIV) briefly highlights key epidemiologic and clinical features in the pulmonary involvement of AIDS-defining malignancies of Kaposi sarcoma and non-Hodgkin lymphoma. Then, focusing on non-AIDS defining lung cancer, the epidemiology and mechanisms, clinical presentation, pathology, treatment and outcomes, and prevention of HIV-associated lung cancer are discussed. Finally, the important knowledge gaps and future directions for research related to HIV-associated lung malignancies are highlighted.

Sonographic findings of nasopharyngeal carcinoma and its involvement in the parapharyngeal space

OBJECTIVES

The purpose of this study was to determine the sonographic performance in pathologically proven cases of nasopharyngeal carcinoma and its involvement in the parapharyngeal space.

METHODS

The study included 58 patients being treated for suspected nasopharyngeal carcinoma detected by routine nasopharyngoscopy who underwent pathologic biopsy. Sonography was performed immediately thereafter with a convex array transducer in both the B-mode and color mode. Forty-five of the 58 patients (90 parapharyngeal spaces) in whom nasopharyngeal carcinoma was proved by both sonography and pathologic biopsy underwent preradiotherapy magnetic resonance imaging (MRI). The sonographic findings were compared to the pathologic findings. The sonographic findings of parapharyngeal space involvement were correlated with the MRI findings.

RESULTS

The normal anatomy of the nasopharynx and parapharyngeal space, nasopharyngeal carcinoma, and its relationship with the parapharyngeal space were well shown on sonography. The sensitivity of sonography for detection of nasopharyngeal carcinoma was 97.8%, and the specificity was 41.7%. The sonographic findings of parapharyngeal space involvement had a high degree of agreement with MRI (κ = 0.757; P < .001).

CONCLUSIONS

These promising initial data indicate that sonography may be a useful tool for diagnosing nasopharyngeal carcinoma and defining the relationship between the tumor and the parapharyngeal space.

Application of contrast-enhanced ultrasound in the diagnosis of solid pancreatic lesions--a comparison of conventional ultrasound and contrast-enhanced CT

OBJECTIVE

To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) by comparison with conventional ultrasound (US) and contrast-enhanced CT (CECT) in solid pancreatic lesions.

METHOD

Ninety patients with solid pancreatic focal lesions were enrolled, including 36 cases of pancreatic carcinoma, 28 cases of pancreatitis, 6 cases of pancreatic neuroendocrine tumor, 12 cases of solid pseudopapillary tumor of the pancreas, 6 cases of pancreatic metastases, 1 case of cavernous hemolymphangioma and 1 case of lymphoma. US and CEUS were applied respectively for the diagnosis of a total of 90 cases of solid pancreatic lesions. The diagnostic results were scored on a 5-point scale. Results of CEUS were compared with CECT.

RESULTS

(1) 3-score cases (undetermined) diagnosed by CEUS were obviously fewer than that of US, while the number of 1-score (definitely benign) and 5-score (definitely malignant) cases diagnosed by CEUS was significantly more than that of US. There was a significant difference in the distribution of final scores using the two methods (p<0.001). The overall diagnostic accuracies of the 90 cases for CEUS and US were 83.33% and 44.44%, respectively, which indicated an obvious advantage for CEUS (p<0.001). (2) The diagnostic consistency among three ultrasound doctors: the kappa values calculated for US were 0.537, 0.444 and 0.525, compared with 0.748, 0.645 and 0.795 for CEUS. The interobserver agreement for CEUS was higher than that for US. (3) The sensitivity, specificity and accuracy of the diagnosis of pancreatic carcinoma with CEUS and CECT were 91.7% and 97.2%, 87.0% and 88.9%, and 88.9% and 92.2%, respectively, while for the diagnosis of pancreatitis, the corresponding indices were 82.1% and 67.9%, 91.9% and 100%, and 88.9% and 90%, respectively, showing no significant differences (p>0.05).

CONCLUSION

CEUS has obvious superiority over conventional US in the general diagnostic accuracy of solid pancreatic lesions and in the diagnostic consistency among doctors. The performances of CEUS are similar to that of CECT in the diagnosis of pancreatic carcinoma and focal pancreatitis.

Mitral annular caseous calcification: a rare variant of a common echocardiographic finding discovered with advanced imaging techniques

We present the case of a 90-year-old diabetic male and medically managed three-vessel coronary artery disease with evidence of an oval, nonmobile echo-density located on the posterior mitral valve annulus measuring two centimeters in diameter without significant impingement of the mitral valve on initial screening echocardiogram which was initially thought to be prominent mitral annular calcification which was later confirmed to be a rare case of caseoma as confirmed by both cardiac magnetic resonance (CMR) as well as coronary computed tomographic angiography (CCTA).

In vivo X-ray computed tomographic imaging of soft tissue with native, intravenous, or oral contrast

X-ray Computed Tomography (CT) is one of the most commonly utilized anatomical imaging modalities for both research and clinical purposes. CT combines high-resolution, three-dimensional data with relatively fast acquisition to provide a solid platform for non-invasive human or specimen imaging. The primary limitation of CT is its inability to distinguish many soft tissues based on native contrast. While bone has high contrast within a CT image due to its material density from calcium phosphate, soft tissue is less dense and many are homogenous in density. This presents a challenge in distinguishing one type of soft tissue from another. A couple exceptions include the lungs as well as fat, both of which have unique densities owing to the presence of air or bulk hydrocarbons, respectively. In order to facilitate X-ray CT imaging of other structures, a range of contrast agents have been developed to selectively identify and visualize the anatomical properties of individual tissues. Most agents incorporate atoms like iodine, gold, or barium because of their ability to absorb X-rays, and thus impart contrast to a given organ system. Here we review the strategies available to visualize lung, fat, brain, kidney, liver, spleen, vasculature, gastrointestinal tract, and liver tissues of living mice using either innate contrast, or commercial injectable or ingestible agents with selective perfusion. Further, we demonstrate how each of these approaches will facilitate the non-invasive, longitudinal, in vivo imaging of pre-clinical disease models at each anatomical site.

SHILO, a novel dual imaging approach for simultaneous HI-/LOw temporal (Low-/Hi-spatial) resolution imaging for vascular dynamic contrast enhanced cardiovascular magnetic resonance: numerical simulations and feasibility in the carotid arteries

BACKGROUND

Dynamic contrast enhanced (DCE) cardiovascular magnetic resonance (CMR) is increasingly used to quantify microvessels and permeability in atherosclerosis. Accurate quantification depends on reliable sampling of both vessel wall (VW) uptake and contrast agent dynamic in the blood plasma (the so called arterial input function, AIF). This poses specific challenges in terms of spatial/temporal resolution and matched dynamic MR signal range, which are suboptimal in current vascular DCE-CMR protocols. In this study we describe a novel dual-imaging approach, which allows acquiring simultaneously AIF and VW images using different spatial/temporal resolution and optimizes imaging parameters for the two compartments. We refer to this new acquisition as SHILO, Simultaneous HI-/LOw-temporal (low-/hi-spatial) resolution DCE-imaging.

METHODS

In SHILO, the acquisition of low spatial resolution single-shot AIF images is interleaved with segments of higher spatial resolution images of the VW. This allows sampling the AIF and VW with different spatial/temporal resolution and acquisition parameters, at independent spatial locations. We show the adequacy of this temporal sampling scheme by using numerical simulations. Following, we validate the MR signal of SHILO against a standard 2D spoiled gradient recalled echo (SPGR) acquisition with in vitro and in vivo experiments. Finally, we show feasibility of using SHILO imaging in subjects with carotid atherosclerosis.

RESULTS

Our simulations confirmed the superiority of the SHILO temporal sampling scheme over conventional strategies that sample AIF and tissue curves at the same time resolution. Both the median relative errors and standard deviation of absolute parameter values were lower for the SHILO than for conventional sampling schemes. We showed equivalency of the SHILO signal and conventional 2D SPGR imaging, using both in vitro phantom experiments (R2 =0.99) and in vivo acquisitions (R2 =0.95). Finally, we showed feasibility of using the newly developed SHILO sequence to acquire DCE-CMR data in subjects with carotid atherosclerosis to calculate plaque perfusion indices.

CONCLUSIONS

We successfully demonstrate the feasibility of using the newly developed SHILO dual-imaging technique for simultaneous AIF and VW imaging in DCE-CMR of atherosclerosis. Our initial results are promising and warrant further investigation of this technique in wider studies measuring kinetic parameters of plaque neovascularization with validation against gold standard techniques.

Feasibility of MR perfusion-weighted imaging by use of a time-spatial labeling inversion pulse

Perfusion-weighted imaging (PWI) by use of arterial spin labeling (ASL) has been introduced to the clinical setting. However, it is not widely available because it requires specialized pulse sequences. Imaging using a time-spatial labeling inversion pulse (time-SLIP), which is a magnetic resonance angiography (MRA) technique that is based on ASL, can be used in various situations. In this study, we examined the feasibility of time-SLIP PWI. Two types of time-SLIP sequences were evaluated: (1) a single inversion recovery (IR) pulse sequence, which is the same as that used in conventional time-SLIP MRA except for the timing of data acquisition, and (2) a dual IR pulse sequence, where a second, non-selective, IR pulse was added during the inflow time to suppress background signals. Subtraction processing is performed between the "on" and "off" settings of the first IR pulse (time-SLIP tag) to obtain PWI. The average signal intensity was measured in a uniform phantom as the residual of the background, and in five healthy subjects as the perfusion signal. The average signal-to-noise ratio (SNR) was also measured in the five subjects. All imaging was performed with a 1.5-T MR scanner. Images using the dual IR method showed lower background signals and higher perfusion signals compared with images using the single IR method. However, the SNR was lower in images with the dual IR method. These results demonstrate that a time-SLIP, which is an MRA method, can be used for obtaining cerebral PWI simply by adjusting the imaging parameters.