Imaging appearance of bone tumors of the maxillofacial region

This paper reviews the imaging appearance of benign and malignant bone tumors of the maxillofacial region. A benign bone tumor commonly appears as a well circumscribed lesion. The matrix of the tumor may be calcified or sclerotic. Malignancies often display aggressive characteristics such as cortical breakthrough, bone destruction, a permeative pattern and associated soft-tissue masses. Computed tomography scan is an excellent imaging modality for accurate localization of the lesion, characterization of the tumor matrix and detection of associated osseous changes such as bone remodeling, destruction or periosteal reaction. Magnetic resonance imaging is of limited value in the evaluation of maxillofacial bone tumors.

Abdominal crush injury in the Sichuan earthquake evaluated by multidetector computed tomography

AIM: To investigate the features of abdominal crush injuries resulting from an earthquake using multidetector computed tomography (MDCT).

METHODS: Fifty-one survivors with abdominal crush injuries due to the 2008 Sichuan earthquake underwent emergency non-enhanced scans with 16-row MDCT. Data were reviewed focusing on anatomic regions including lumbar vertebrae, abdominal wall soft tissue, retroperitoneum and intraperitoneal space; and types of traumatic lesions.

RESULTS: Fractures of lumbar vertebrae and abdominal wall soft tissue injuries were more common than retro- and intraperitoneal injuries (P < 0.05). With regard to the 49 lumbar vertebral fractures in 24 patients, these occurred predominantly in the transverse process (P < 0.05), and 66.67% of patients (16/24) had fractures of multiple vertebrae, predominantly two vertebrae in 62.5% of patients (10/16), mainly in L1-3 vertebrae in 81.63% of the vertebrae (40/49). Retroperitoneal injuries occurred more frequently than intraperitoneal injuries (P < 0.05), and renal and liver injuries were most often seen in the retroperitoneum and in the intraperitoneal space, respectively (all P < 0.05).

CONCLUSION: Transverse process fractures in two vertebrae among L1-3 vertebrae, injury of abdominal wall soft tissue, and renal injury might be features of earthquake-related crush abdominal injury.

Era of diagnostic and interventional ultrasound

It is an era of diagnostic and interventional ultrasound (US). Various new techniques such as three-dimensional US (3D US), interventional US, and contrast-enhanced US (CEUS) have been introduced into clinical practice. Dr. Xu and his colleagues have taken advantage of these techniques and carried out a series of relevant studies. Their use of 3D US in the liver, gallbladder, liver tumor volumetry, guidance for ablation, and 3D CEUS has widened the application of 3D US in the clinic. They found that prognosis in patients with hepatocellular carcinoma (HCC) after thermal ablation with curative intent was determined by treatment response to ablation, pretreatment serum AFP, and liver function reserve. Tumor response to treatment was the most predictive factor for long-term survival. They compared the use of percutaneous microwave ablation and radiofrequency ablation for the treatment of HCC and found that both are effective methods in treating HCCs. The local tumor control, complications related to treatment, and long-term survival were equivalent for the two modalities. They first compared the enhancement patterns of HCC and intrahepatic cholangiocarcinoma (ICC) and proposed the diagnostic clues for ICC, liver angiomyolipoma (AML), gallbladder cancer, renal carcinoma, and renal AML, which have greatly enhanced the role of CEUS in the clinic. They also evaluated the diagnostic performance of CEUS in characterizing complex cystic focal liver lesions and the agreement between two investigators with different experience levels; and found that CEUS is especially useful for the young investigator. They assessed the effect of anti-angiogenic gene therapy for HCC treated by microbubble-enhanced US exposure and concluded that gene therapy mediated by US exposure enhanced by a microbubble contrast agent may become a new treatment option for HCC.

Imaging features of a huge spermatic cord leiomyosarcoma: Review of the literature

Spermatic cord leiomyosarcomas (LMSs) are rare tumors which may cause significant morbidity and mortality if inadequately diagnosed or treated. We report a case of a paratesticular LMS in a 60-year-old man who presented with a right scrotal mass. The patient was evaluated by scrotal ultrasound and computed tomography of the abdomen and pelvis (including scans of the scrotum), which revealed a large extratesticular mass. The lesion proved to be malignant and the patient underwent radical orchiectomy with high cord ligation. To improve the assignment of this lesion, we further analyze the imaging features of LMS and correlate them with pathologic findings.

Applications of multi-nuclear magnetic resonance spectroscopy at 7T

AIM: To discuss the advantages of ultra-high field (7T) for ¹H and ¹³C magnetic resonance spectroscopy (MRS) studies of metabolism.

METHODS: Measurements of brain metabolites were made at both 3 and 7T using ¹H MRS. Measurements of glycogen and lipids in muscle were measured using ¹³C and ¹H MRS respectively.

RESULTS: In the brain, increased signal-to-noise ratio (SNR) and dispersion allows spectral separation of the amino-acids glutamate, glutamine and γ-aminobutyric acid (GABA), without the need for sophisticated editing sequences. Improved quantification of these metabolites is demonstrated at 7T relative to 3T. SNR was 36% higher, and measurement repeatability (% coefficients of variation) was 4%, 10% and 10% at 7T, vs 8%, 29% and 21% at 3T for glutamate, glutamine and GABA respectively. Measurements at 7T were used to compare metabolite levels in the anterior cingulate cortex (ACC) and insula. Creatine and glutamate levels were found to be significantly higher in the insula compared to the ACC (P < 0.05). In muscle, the increased SNR and spectral resolution at 7T enables interleaved studies of glycogen (¹³C) and intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) (¹H) following exercise and re-feeding. Glycogen levels were significantly decreased following exercise (-28% at 50% VO₂ max; -58% at 75% VO₂ max). Interestingly, levels of glycogen in the hamstrings followed those in the quadriceps, despite reduce exercise loading. No changes in IMCL and EMCL were found in the study.

CONCLUSION: The demonstrated improvements in brain and muscle MRS measurements at 7T will increase the potential for use in investigating human metabolism and changes due to pathologies.

Feng Chen's work on translational and clinical imaging

Dr. Feng Chen is a chief medical doctor and the vice chairman of the Department of Radiology in Zhong Da Hospital at Southeast University, Nanjing, China and a senior researcher in the Department of Radiology at the Catholic University of Leuven, Belgium. His main areas of interest are translational imaging research including stroke, tumor angiogenesis, assessment of therapeutic response in solid tumors, and magnetic resonance contrast media. Dr. Feng Chen has published 44 scientific papers in peer-reviewed international journals. He and his colleagues have developed an imaging platform which includes animal models, animal preparations and multiparametric magnetic resonance imaging (MRI) protocols for translational animal imaging research using clinical machines. His MRI findings on rodent stroke are considered to "serve as a model for future laboratory investigations of treatment of acute stroke and unify the approaches developed for clinical studies". He and his colleagues have introduced a novel liver tumor model in rodents, in which a series of studies concerning the antitumor activity of vascular disrupting agents have been successively conducted and assessed by in vivo MRI, especially by diffusion weighted imaging as an imaging biomarker. His goal is to provide valuable references for clinical practice and to contribute to the translation of animal imaging research into patient applications.

Clinical significance of magnetic resonance imaging findings in rectal cancer

Staging of rectal cancer is essential to help guide clinicians to decide upon the correct type of surgery and determine whether or not neoadjuvant therapy is indicated. Magnetic resonance imaging (MRI) is currently one of the most accurate modalities on which to base treatment decisions for patients with rectal cancer. MRI can accurately detect the mesorectal fascia, assess the invasion of the mesorectum or surrounding organs and predict the circumferential resection margin. Although nodal disease remains a difficult radiological diagnosis, new lymphographic agents and diffusion weighted imaging may allow identification of metastatic nodes by criteria other then size. In light of this, we have reviewed the literature on the accuracy of specific MRI findings for staging the local extent of primary rectal cancer. The aim of this review is to establish a correlation between MRI findings, prognosis, and available treatment options.

Ultrasonography of normal and abnormal appendix in children

Appendicitis is the most common acute surgical emergency of childhood. Since the original report by Puylaert in 1986, the use of ultrasonography in the diagnosis of appendicitis has been the subject of considerable study. Among the reported diagnostic criteria, the maximal outer diameter (MOD) of the appendix is accepted as the one of the most reliable criteria used to differentiate between a normal appendix and acute appendicitis. However, MOD measurement is subject to inaccuracies because luminal distention by non-compressible, non-inflammatory material such as fecal material, or increased maximal mural thickness due to reactive mucosal lymphoid hyperplasia, or a medical cause due to a generalized gastrointestinal disease, such as Crohn’s disease, can cause the measurement to exceed the upper limits of normality. The aim of this article is to introduce the spectrum of ultrasonographic findings in the normal and abnormal appendix and eventually to reduce unnecessary surgery in children.

Applications of new irradiation modalities in patients with lymphoma: Promises and uncertainties

New highly conformal irradiation modalities have emerged for treatment of Hodgkin lymphoma. Helical tomotherapy offers both intensity-modulated irradiation and accurate patient positioning and was shown to significantly decrease radiation doses to the critical organs. Here we review some of the most promising applications of helical tomotherapy in Hodgkin disease. By decreasing doses to the heart or the breast, helical tomotherapy might decrease the risk of long-term cardiac toxicity or secondary breast cancers, which are major concerns in patients receiving chest radiotherapy. Other strategies, such as debulking radiotherapy prior to stem cell transplantation or total lymphoid irradiation may be clinically relevant. However, helical tomotherapy may also increase the volume of tissues that receive lower doses, which has been implicated in the carcinogenesis process. Prospective assessments of these new irradiation modalities of helical tomotherapy are required to confirm the potential benefits of highly conformal therapies applied to hematological malignancies.

A promising diagnostic method: Terahertz pulsed imaging and spectroscopy

The terahertz band lies between the microwave and infrared regions of the electromagnetic spectrum. This radiation has very low photon energy and thus it does not pose any ionization hazard for biological tissues. It is strongly attenuated by water and very sensitive to water content. Unique absorption spectra due to intermolecular vibrations in this region have been found in different biological materials. These unique features make terahertz imaging very attractive for medical applications in order to provide complimentary information to existing imaging techniques. There has been an increasing interest in terahertz imaging and spectroscopy of biologically related applications within the last few years and more and more terahertz spectra are being reported. This paper introduces terahertz technology and provides a short review of recent advances in terahertz imaging and spectroscopy techniques, and a number of applications such as molecular spectroscopy, tissue characterization and skin imaging are discussed.

Estimation of intra-operator variability in perfusion parameter measurements using DCE-US

AIM: To investigate intra-operator variability of semi-quantitative perfusion parameters using dynamic contrast-enhanced ultrasonography (DCE-US), following bolus injections of SonoVue^®.

METHODS: The in vitro experiments were conducted using three in-house sets up based on pumping a fluid through a phantom placed in a water tank. In the in vivo experiments, B16F10 melanoma cells were xenografted to five nude mice. Both in vitro and in vivo, images were acquired following bolus injections of the ultrasound contrast agent SonoVue^® (Bracco, Milan, Italy) and using a Toshiba Aplio^® ultrasound scanner connected to a 2.9-5.8 MHz linear transducer (PZT, PLT 604AT probe) (Toshiba, Japan) allowing harmonic imaging (“Vascular Recognition Imaging”) involving linear raw data. A mathematical model based on the dye-dilution theory was developed by the Gustave Roussy Institute, Villejuif, France and used to evaluate seven perfusion parameters from time-intensity curves. Intra-operator variability analyses were based on determining perfusion parameter coefficients of variation (CV).

RESULTS: In vitro, different volumes of SonoVue^® were tested with the three phantoms: intra-operator variability was found to range from 2.33% to 23.72%. In vivo, experiments were performed on tumor tissues and perfusion parameters exhibited values ranging from 1.48% to 29.97%. In addition, the area under the curve (AUC) and the area under the wash-out (AUWO) were two of the parameters of great interest since throughout in vitro and in vivo experiments their variability was lower than 15.79%.

CONCLUSION: AUC and AUWO appear to be the most reliable parameters for assessing tumor perfusion using DCE-US as they exhibited the lowest CV values.

Paraparesis induced by extramedullary haematopoiesis

We describe a case of worsening paraparesis induced by spinal cord compression at T6-T7 levels associated with compensatory extramedullary haematopoiesis from a compound heterozygote for haemoglobin E and for β-thalassemia. An emergency T3-T9 laminectomy was performed with excision of the masses and complete rehabilitation of the patient.

MDCT in the diagnostic algorithm in patients with symptomatic atrial fibrillation

Atrial fibrillation (AF) is the most common supraventricular arrhythmia and a major cause of morbidity. Arrhythmogenic foci originating within the pulmonary veins (PVs) are an important cause of both paroxysmal and persistent AF. A variety of endovascular and surgical techniques have been used to electrically isolate the PV from the left atrium. Pulmonary venography for localization of the PV ostium can be difficult to perform during the ablation procedure. While the anatomy of the PV is patient-specific, non-invasive imaging techniques may provide useful diagnostic information prior to the intended intervention. In this context, multidetector computed tomography (MDCT) visualization of the left atrial and PV anatomy prior to left atrial ablation and PV isolation is becoming increasingly important. MDCT imaging provides pre-procedural information on the left atrial anatomy, including atrial size and venous attachments, and it may identify potential post-procedural complications, such as pulmonary vein stenosis or cardiac perforations. Here, we review the relevant literature and present the current “state-of-the-art” of left atrial anatomy, PV ostia as well as the clinical aspects of refractory AF, MDCT imaging protocols and procedural aspects of PV ablation.

Use of carbon dioxide as negative contrast agent for magnetic resonance cholangiopancreatography

AIM: To evaluate the effects of using CO₂ as negative contrast agent in decreasing the overlapping on the pancreaticobiliary system from intestinal fluids.

METHODS: We evaluated the magnetic resonance cholangiopancreatography (MRCP) images in 117 patients divided into two groups (group 1, without taking gas producing crystals to produce CO₂, n = 64; group 2, with CO₂, n = 53) in a 1.5T unit using MRCP sequence. Anatomic locations of intestinal fluids distribution, overlapping with common bile duct (CBD) and pancreatic duct (PD), were evaluated.

RESULTS: In the group with CO₂, the decrease in distribution of intestinal fluids was significant in the gastric antrum (P = 0.001) and duodenal bulb (P < 0.001), but not in the gastric fundus and body and in the second portion of the duodenum (P = 1.000, P = 0.171, and P = 0.584 respectively). In the group with CO₂, the decrease in overlapping with CBD was significant (P < 0.001), but the decrease in overlapping with PD was not (P = 0.106).

CONCLUSION: MRCP with carbon dioxide as negative contrast agent would decrease intestinal fluids in the gastric antrum and duodenal bulb, thereby decreasing overlapping with the CBD.

Miliary nodules due to secondary pulmonary hemosiderosis in rheumatic heart disease

Pulmonary hemosiderosis is defined as the clinical and functional consequence of iron overload of the lungs, which usually occurs due to recurrent intra-alveolar bleeding. It can manifest as miliary mottling and should be entertained in the differential diagnosis of patients presenting with miliary nodules on chest radiography, especially those with mitral stenosis. The management of secondary pulmonary hemosiderosis secondary to valvular heart disease includes valvuloplasty and/or valve replacement. The radiological opacities may disappear with successful treatment of the underlying valvular disease in many patients. However, they may persist with no physiological impairment to the patient. Here, we present a 32-year-old man with mitral stenosis who presented with fever and miliary shadows on chest radiography, which was ultimately diagnosed as secondary pulmonary hemosiderosis.

Content-based image retrieval applied to BI-RADS tissue classification in screening mammography

AIM

To present a content-based image retrieval (CBIR) system that supports the classification of breast tissue density and can be used in the processing chain to adapt parameters for lesion segmentation and classification.

METHODS

Breast density is characterized by image texture using singular value decomposition (SVD) and histograms. Pattern similarity is computed by a support vector machine (SVM) to separate the four BI-RADS tissue categories. The crucial number of remaining singular values is varied (SVD), and linear, radial, and polynomial kernels are investigated (SVM). The system is supported by a large reference database for training and evaluation. Experiments are based on 5-fold cross validation.

RESULTS

Adopted from DDSM, MIAS, LLNL, and RWTH datasets, the reference database is composed of over 10 000 various mammograms with unified and reliable ground truth. An average precision of 82.14% is obtained using 25 singular values (SVD), polynomial kernel and the one-against-one (SVM).

CONCLUSION

Breast density characterization using SVD allied with SVM for image retrieval enable the development of a CBIR system that can effectively aid radiologists in their diagnosis.

Breast and lung metastasis from pancreatic neuroendocrine carcinoma

Pancreatic neuroendocrine tumors (PNETs) are an uncommon malignancy, accounting for a small percentage of all pancreatic malignancies. Due to their insidious course, most PNETs present with metastatic disease. Although reports in the literature describe PNET metastasis to the liver, lung and brain, to date there are no reports of stage IV disease involving the breast. Moreover, the lack of consensus regarding classification and treatment of this entity leaves practitioners without standards of practice or a firm base from which to formulate prognosis. In this report, the case of a previously healthy 51-year-old woman with stage IV PNET is examined. After combined neoadjuvant therapy with 5-fluorouracil, carboplatin, etoposide and radiation, surgical resection revealed metastatic PNET to the breast and lung, with no microscopic evidence of residual disease within the pancreas. An extensive analysis of the presentation, diagnosis, imaging modalities, treatment options, and prognosis is included in the discussion. As demonstrated by our review, there is a need for further studies to delineate inconclusive evidence with respect to subtype classification, treatment and prognosis of PNETs.

Multiparametric MRI biomarkers for measuring vascular disrupting effect on cancer

Solid malignancies have to develop their own blood supply for their aggressive growth and metastasis; a process known as tumor angiogenesis. Angiogenesis is largely involved in tumor survival, progression and spread, which are known to be significantly attributed to treatment failures. Over the past decades, efforts have been made to understand the difference between normal and tumor vessels. It has been demonstrated that tumor vasculature is structurally immature with chaotic and leaky phenotypes, which provides opportunities for developing novel anticancer strategies. Targeting tumor vasculature is not only a unique therapeutic intervention to starve neoplastic cells, but also enhances the efficacy of conventional cancer treatments. Vascular disrupting agents (VDAs) have been developed to disrupt the already existing neovasculature in actively growing tumors, cause catastrophic vascular shutdown within short time, and induce secondary tumor necrosis. VDAs are cytostatic; they can only inhibit tumor growth, but not eradicate the tumor. This novel drug mechanism has urged us to develop multiparametric imaging biomarkers to monitor early hemodynamic alterations, cellular dysfunctions and metabolic impairments before tumor dimensional changes can be detected. In this article, we review the characteristics of tumor vessels, tubulin-destabilizing mechanisms of VDAs, and in vivo effects of the VDAs that have been mostly studied in preclinical studies and clinical trials. We also compare the different tumor models adopted in the preclinical studies on VDAs. Multiparametric imaging biomarkers, mainly diffusion-weighted imaging and dynamic contrast-enhanced imaging from magnetic resonance imaging, are evaluated for their potential as morphological and functional imaging biomarkers for monitoring therapeutic effects of VDAs.

CT patterns of nodal disease in pediatric chest tuberculosis

AIM: To highlight various patterns of nodal involvement and post treatment changes in pediatric chest tuberculosis based on contrast enhanced computed tomography (CECT) scans of chest.

METHODS: This was a retrospective study consisting of 91 patients aged less than 17 years, who attended pediatric OPD of All India Institute of Medical Sciences with clinically diagnosed tuberculosis or with chest radiographs suggestive of chest tuberculosis. These patients had an initial chest radiograph as well as CECT of the chest and follow up imaging after 6 mo, and in some cases 9 mo, of completion of anti-tubercular treatment (ATT). CECT of these patients was reviewed for the location and extent of nodal involvement along with determination of site, size, enhancement pattern and calcification.

RESULTS: Enlargement of mediastinal or hilar lymph nodes was found in 88/91 patients (96.7%), with the most common locations being paratracheal (84.1%), and subcarinal (76.1%). The most common pattern of enhancement was found to be inhomogenous. The nodes were conglomerate in 56.8% and discrete in 43.2%. In addition, perinodal fat was obscured in 84.1% of patients. In the post-treatment scan, there was 87.4% reduction in the size of the nodes. All nodes post-treatment were discrete and homogenous with perinodal fat present. Calcification was found both pre- and post-treatment, but there was an increase in incidence after treatment (41.7%). There was hence a reduction in size, change in enhancement pattern, and appearance of perinodal fat with treatment.

CONCLUSION: Tubercular nodes have varied appearance and enhancement pattern. Conglomeration and obscuration of perinodal fat suggest activity. In residual nodes decision to continue ATT requires clinical correlation.

Gallstone in jejunal limb with jejunocolonic fistula 10 years after Roux-en-Y choledochojejunostomy

Roux-en-Y choledochojejunostomy is a common biliary reconstruction procedure. The collection of gallstones in the jejunal limb is a rare complication. Here we present a case of a 61-year-old Chinese female who received Roux-en-Y choledochojejunostomy 10 years ago. Diagnosis of recurrent bile duct stones accompanying infection was made before operation. She also had an abdominal mass which was possibly an intussuscepted colon or a huge fecolith. At laparotomy, an oval stone (5 cm in diameter) and 3 smaller multifaceted stones (2 cm in diameter) were found in the jejunal limb. A fistula between this jejunum and colon was also found. Although the typical manifestations of diarrhea were present, the diagnosis of a biliary colonic fistula was missed before operation. Partial colectomy was performed with the fistulous opening repaired. A T-tube was left in the jejunal limb and the mesocolon aperture was enlarged and revised. Her postoperative convalescence was uneventful. We report this case hoping to sharpen our diagnostic acumen.

Missed incidental vertebral compression fractures on computed tomography imaging: More optimism justified

Missed incidental vertebral compression fractures on computed tomography (CT) imaging are a common problem. Although numerous publications are available on this topic, recent publications still show a high percentage of such missed fractures. The rate of such missed fractures in the authors department is much lower than that in the reported literature when routine multiplanar reconstructions are used for reporting CT scans. Therefore, a more optimistic view on this topic seems to be justified.

Transarterial chemoembolization with miriplatin-lipiodol emulsion for neuroendocrine metastases of the liver

Miriplatin, a cisplatin derivative with a high affinity for iodized oil, is a novel chemotherapeutic agent designed for use in the transarterial treatment of hepatocellular carcinoma. This case report describes our experience with transarterial chemoembolization (TACE) using miriplatin in 2 patients with neuroendocrine liver metastases. A 38-year-old man with multiple neuroendocrine liver metastases was treated by whole liver chemoembolization, and a 35-year-old woman with a single hepatic lesion was treated by superselective chemoembolization. No serious adverse events were noted during the interventional procedures, or during the observation period of 3 mo in either patient. Sufficient iodized oil uptake was observed in the hypervascular lesions on the unenhanced computed tomography (CT) at 7 d after the procedure. Contrast-enhanced CT obtained at 3 mo after chemoembolization revealed that all hepatic lesions were substantially reduced in size irrespective of tumor vascularity or degree of cystic degeneration, although iodized oil accumulation was only marginal for lesions with cystic degeneration. Thus, TACE with miriplatin can be a safe and effective therapeutic option for the treatment of neuroendocrine metastases of the liver.

Percutaneous cecostomy in the management of organic fecal incontinence in children

AIM: To assess the effectiveness and safety of imaging-guided percutaneous cecostomy in the management of pediatric patients with organic fecal incontinence.

METHODS: Twenty three cecostomies were performed on 21 children with organic fecal incontinence (13 males, 8 females), aged from 5 to 16 years (mean 9.5 years). Thirteen patients had neurogenic fecal incontinence and 8 patients had anorectal anomalies. Procedures were performed under general anesthesia and fluoroscopic guidance. Effectiveness and complication data were obtained for at least 1 year after the procedure.

RESULTS: Cecostomy was successful in 20 patients (primary technical success rate 95%). Cecostomy failed in one patient due to tube breakage (secondary technical success rate 100%). The tubes were in situ for an average of 18 mo (range 12-23 mo). Eighteen patients (87%) expressed satisfaction with the procedures. Resolution of soiling was achieved in all patients with neurogenic fecal incontinence (100%) and in 5 of 8 patients with anorectal anomalies (62.5%). Eleven patients (52%) experienced minor problems. No major complications were noted.

CONCLUSION: Percutaneous cecostomy improves the quality of life in children with organic fecal incontinence. A satisfactory outcome is more prevalent in patients with neurogenic fecal incontinence than anorectal anomalies.

Contrast-enhanced ultrasound in diagnosis and characterization of focal hepatic lesions

The extensive use of imaging techniques in differential diagnosis of abdominal conditions and screening of hepatocellular carcinoma in patients with chronic hepatic diseases, has led to an important increase in identification of focal liver lesions. The development of contrast-enhanced ultrasound (CEUS) opens a new window in the diagnosis and follow-up of these lesions. This technique offers obvious advantages over the computed tomography and magnetic resonance, without a decrease in its sensitivity and specificity. The new second generation contrast agents, due to their intravascular distribution, allow a continuous evaluation of the enhancement pattern, which is crucial in characterization of liver lesions. The dual blood supply in the liver shows three different phases, namely arterial, portal and late phases. The enhancement during portal and late phases can give important information about the lesion’s behavior. Each liver lesion has a different enhancement pattern that makes possible an accurate approach to their diagnosis. The role of emerging techniques as a contrast-enhanced three-dimensional US is also discussed. In this article, the advantages, indications and technique employed during CEUS and the different enhancement patterns of most benign and malignant focal liver lesions are discussed.

Takao Hiraki’s work on interventional radiology

Dr. Takao Hiraki is a scientist carrying out interventional radiology research in the Department of Radiology at Okayama University Medical School, Japan. He has conducted animal and human clinical studies on interventional radiology for various conditions. For example, he clarified the hepatic hemodynamic changes caused by hepatic venous occlusion. He also developed new devices, such as hydrogel coils for the occlusion of the aneurismal sac after an endovascular stent-graft of an aortic aneurysm to prevent endoleakage and small intestinal submucosa-covered stents for transjugular intrahepatic portosystemic shunts. Further, he performed a number of studies on the radiofrequency ablation of lung cancer, mediastinal lymph node metastasis, and computed tomography-fluoroscopy-guided lung biopsies. He intends to continue to dedicate his academic career to expand the role of interventional radiology in clinical medicine.

Perfusion characterization of liver metastases from endocrine tumors: Computed tomography perfusion

AIM: To assess prospectively parameters of computed tomography perfusion (CT p) for evaluation of vascularity of liver metastases from neuroendocrine tumors.

METHODS: This study was approved by the hospital’s institutional review board. All 18 patients provided informed consent. There were 30 liver metastases from neuroendocrine tumors. Patients were divided into three groups depending on the appearance of the liver metastases at the arterial phase of morphological CT (hyperdense, hypodense and necrotic). Sequential acquisition of the liver was performed before and for 2 min after intravenous injection of 0.5 mg/kg contrast medium, at 4 mL/s. Data were analyzed using deconvolution analysis to calculate blood flow (BF), blood volume (BV), mean transit time (MTT), hepatic arterial perfusion index (HAPI) and a bi-compartmental analysis was performed to obtain vascular permeability-surface area product (PS). Post-treatment analysis was performed by a radiologist and regions of interest were plotted on the metastases, normal liver, aorta and portal vein.

RESULTS: At the arterial phase of the morphological CT scan, the aspects of liver metastases were hyperdense (n = 21), hypodense (n = 7), and necrotic (n = 2). In cases of necrotic metastases, none of the CT p parameters were changed. Compared to normal liver, a significant difference in all CT p parameters was found in cases of hyperdense metastases, and only for HAPI and MTT in cases of hypodense metastases. No significant difference was found for MTT and HAPI between hypo- and hyperdense metastases. A significant decrease of PS, BV and BF was demonstrated in cases of patients with hypodense lesions PS (23 ± 11.6 mL/100 g per minute) compared to patients with hyperdense lesions; PS (13.5 ± 10.4 mL/100 g per minute), BF (93.7 ± 75.4 vs 196.0 ± 115.6 mL/100 g per minute) and BV (9.7 ± 5.9 vs 24.5 ± 10.9 mL/100 g).

CONCLUSION: CT p provides additional information compared to the morphological appearance of liver metastases.

Technological innovations in digital data management and changing roles of imaging specialists in Japan

Technical innovations in digital data management pose a threat to radiologists in that can we remain in the process of clinical decision making or be assigned to a secondary role in future clinical practice. The value added to the imaging studies by diagnostic radiologists, or imaging specialists, has never been questioned more seriously.

Multislice CT virtual intravascular endoscopy of aortic dissection: A pictorial essay

AIM: To present our experience of using 3D virtual intravascular endoscopy (VIE) to characterize and evaluate the intraluminal appearances of aortic dissection.

METHODS: Ten patients with known aortic dissection underwent dual-source computed tomography angiography and were included in the study. In addition to 2D axial and multiplanar reformatted images as well as 3D reconstructions, VIE images were created in each patient to demonstrate intraluminal views of the aorta and its branches, origin of artery branches and artery branch involvement by aortic dissection.

RESULTS: Stanford A dissection was found in 8 patients and B dissection in the remaining 2 patients. VIE images were successfully generated in all of the patients with excellent visualization of the normal anatomical structures, intimal flap and intimal entrance tear, communication between true and false lumens, as well as assessment of the extent of aortic dissection.

CONCLUSION: Our preliminary experience suggests that VIE could be used as a complementary tool to assist radiologists accurately evaluate aortic dissection so that better patient management can be achieved.

Pathophysiology of nephrogenic systemic fibrosis: A review of experimental data

Since the association between nephrogenic systemic fibrosis (NSF) and gadolinium contrast agents (Gd-CAs) was suggested in 2006, several experimental studies have been published to elucidate the role of these agents in the pathogenesis of NSF. Low stability Gd-CAs have a stimulant effect on human skin and fibroblasts in culture and modulate the production of collagen by these cells. Low stability agents have also induced NSF-like skin changes in a rat model with normal renal function after multiple repeat administrations. The role of the 5/6 subtotal nephrectomy rat model in investigating NSF remains under evaluation.

Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET

AIM: To study the peripheral dose (PD) from high-energy photon beams in radiotherapy using the metal oxide semiconductor field effect transistor (MOSFET) dose verification system.

METHODS: The radiation dose absorbed by the MOSFET detector was calculated taking into account the manufacturer’s Correction Factor, the Calibration Factor and the threshold voltage shift. PD measurements were carried out for three different field sizes (5 cm × 5 cm, 10 cm × 10 cm and 15 cm × 15 cm) and for various depths with the source to surface distance set at 100 cm. Dose measurements were realized on the central axis and then at distances (1 to 18 cm) parallel to the edge of the field, and were expressed as the percentage PD (% PD) with respect to the maximum dose (d_max). The accuracy of the results was evaluated with respect to a calibrated 0.3 cm³ ionization chamber. The reproducibility was expressed in terms of standard deviation (s) and coefficient of variation.

RESULTS: % PD is higher near the phantom surface and drops to a minimum at the depth of d_max, and then tends to become constant with depth. Internal scatter radiation is the predominant source of PD and the depth dependence is determined by the attenuation of the primary photons. Closer to the field edge, where internal scatter from the phantom dominates, the % PD increases with depth because the ratio of the scatter to primary increases with depth. A few centimeters away from the field, where collimator scatter and leakage dominate, the % PD decreases with depth, due to attenuation by the water. The % PD decreases almost exponentially with the increase of distance from the field edge. The decrease of the % PD is more than 60% and can reach up to 90% as the measurement point departs from the edge of the field. For a given distance, the % PD is significantly higher for larger field sizes, due to the increase of the scattering volume. Finally, the measured PD obtained with MOSFET is higher than that obtained with an ionization chamber with percentage differences being from 0.6% to 34.0%. However, when normalized to the central d_max this difference is less than 1%. The MOSFET system, in the early stage of its life, has a dose measurement reproducibility of within 1.8%, 2.7%, 8.9% and 13.6% for 22.8, 11.3, 3.5 and 1.3 cGy dose assessments, respectively. In the late stage of MOSFET life the corresponding values change to 1.5%, 4.8%, 11.1% and 29.9% for 21.8, 2.9, 1.6 and 1.0 cGy, respectively.

CONCLUSION: Comparative results acquired with the MOSFET and with an ionization chamber show fair agreement, supporting the suitability of this measurement for clinical in vivo dosimetry.

Radiofrequency ablation of hepatocellular carcinoma: Current status

Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment.

Multiple progressive focal nodular hyperplasia lesions of liver in a patient with hemosiderosis

Focal nodular hyperplasia (FNH) is the second most common benign lesion of the liver. It is a solitary lesion and usually does not enlarge. We present the magnetic resonance imaging findings of multiple progressive FNH lesions in a patient with hemosiderosis using Gadolinium-EOB-DTPA (Eovist) as a hepatobiliary contrast agent. The possible mechanisms underlying the occurrence and progression of FNH lesions and the potential value of Eovist in characterizing the lesions were discussed.

Spectrum of diagnostic errors in radiology

Diagnostic errors are important in all branches of medicine because they are an indication of poor patient care. Since the early 1970s, physicians have been subjected to an increasing number of medical malpractice claims. Radiology is one of the specialties most liable to claims of medical negligence. Most often, a plaintiff's complaint against a radiologist will focus on a failure to diagnose. The etiology of radiological error is multi-factorial. Errors fall into recurrent patterns. Errors arise from poor technique, failures of perception, lack of knowledge and misjudgments. The work of diagnostic radiology consists of the complete detection of all abnormalities in an imaging examination and their accurate diagnosis. Every radiologist should understand the sources of error in diagnostic radiology as well as the elements of negligence that form the basis of malpractice litigation. Error traps need to be uncovered and highlighted, in order to prevent repetition of the same mistakes. This article focuses on the spectrum of diagnostic errors in radiology, including a classification of the errors, and stresses the malpractice issues in mammography, chest radiology and obstetric sonography. Missed fractures in emergency and communication issues between radiologists and physicians are also discussed.

Incidental vertebral compression fractures in imaging studies: Lessons not learned by radiologists

AIM: To assess radiologists reporting rates of incidental vertebral compression fractures in imaging studies.

METHODS: We performed a review of the current literature on the prevalence and reporting rates of incidental vertebral compression fractures in radiologic examinations.

RESULTS: The bibliographic search revealed 12 studies: 7 studies using conventional radiology and 5 using multidetector computed tomography (MDCT). The loss of height cut-off to define a vertebral fracture varied from 15% to 25%. Fracture prevalence was high (mean 21.1%; range 9.5%-35%) in both radiographic and MDCT studies (mean 21.6% and 20.2%, respectively). Reporting rates were low with a mean value of 27.4% (range 0%-66.3%) and were significantly lower in MDCT than in radiographic studies (mean 8.1% vs 41.1%). Notably, recent studies showed lower reporting rates than older studies.

CONCLUSION: Many scientific studies have confirmed a high prevalence of vertebral compression fractures as incidental findings on imaging studies. However, the underreporting of these fractures, as determined in our study, may negatively affect patient care.

Mirizzi syndrome type Va: A rare coexistence of double cholecysto-biliary and cholecysto-enteric fistulae

Mirizzi syndrome is a rare cause of intermittent obstructive jaundice, where an impacted stone in the cystic duct or Hartmann’s pouch mechanically obstructs the common bile duct (CBD). We report a rare case of double cholecysto-biliary and cholecysto-enteric fistulae, in a 75-year-old female patient, presenting with a right upper quadrant abdominal pain and intermittent obstructive jaundice. Endoscopic retrograde cholangiopancreatography suggested Mirizzi syndrome. Operative findings included erosions of the lateral wall of the CBD and the second portion of the duodenum due to impacted gallstones. The defects were reconstructed primarily and a Kehr tube was inserted. The patient had an uneventful postoperative course and was discharged on the 14th postoperative day.

My road on interventional radiology

The author tells a story of how he has become an expert of interventional radiotherapy from a graduate of middle school. In his childhood, he wanted to become an astronomer. However, he was forced to go to the countryside as a school graduate. In 1974, he was enrolled as a “worker-peasant-soldier” student in Henan Medical College. After graduated from the college, he was assigned to the Radiology Department of the First Affiliated Hospital of Henan Medical College where he worked hard as an assistant doctor. Then, he was transferred to Nanfang Hospital (Guangzhou, China) where he achieved great successes and thus has become an expert of interventional radiology.

Arterial spin labeling in neuroimaging

Arterial spin labeling (ASL) is a magnetic resonance imaging technique for measuring tissue perfusion using a freely diffusible intrinsic tracer. As compared with other perfusion techniques, ASL offers several advantages and is now available for routine clinical practice in many institutions. Its noninvasive nature and ability to quantitatively measure tissue perfusion make ASL ideal for research and clinical studies. Recent technical advances have increased its sensitivity and also extended its potential applications. This review focuses on some basic knowledge of ASL perfusion, emerging techniques and clinical applications in neuroimaging.

Accessory spleen-like masses in oncology patients: Are they always benign?

AIM: To assess retrospectively the significance of accessory spleen-like mass (ASLM) in oncology patients undergoing positron emission tomography/computed tomography (PET/CT).

METHODS: The results of PET/CT of 913 patients (278 lymphoma; 635 solid tumors) were reviewed. The number, size, location and attenuation of all ASLMs, and spleen attenuation, were recorded. ASLM fluorodeoxyglucose uptake was graded as normal (less than or equal to that in the liver) or representative of malignancy (more than in the liver). Follow-up PET/CT in patients with ASLM was reviewed when available. ASLM size and attenuation for spleen and ASLM were compared by unpaired Student’s t test. The χ² and Fisher’s exact tests were used to compare ASLM frequency and uptake for lymphomatous and solid tumors, respectively.

RESULTS: ASLM frequency was 14.8%, with 152 ASLMs found in 135 patients. Mean attenuation was lower in ASLM compared with spleen by enhanced and non-enhanced CT (80.7 ± 20.4 HU vs 92.0 ± 14.4 HU, P < 0.0011 and 42.3 ± 9.0 HU vs 51.5 ± 6.3 HU, P < 0.0001, respectively). ASLM incidence was higher in lymphoma patients (56/278, 20.1%) than in those with solid tumors (56/278, 20.1% vs 79/635, 12.4%, P = 0.0036). Pathological uptake was found in four (7.1%) lymphoma patients but not in any patients with a solid tumor (P = 0.028) and it upstaged one patient with lymphoma. Follow-up PET/CT within 3-16 mo was available in 54% of patients with ASLM. Lesion regression was noted in all four pathological ASLMs on follow-up PET/CT after chemotherapy.

CONCLUSION: In patients with lymphoma, ASLM can represent malignancy, and thus further characterization with PET/CT might be warranted. Patients with neoplasia other than ASLM can be confidently diagnosed with accessory spleen.

Interventional treatment of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations (PAVM) are congenital vascular communications in the lungs. They act as right to left shunts so that the blood running through these malformations is not oxygenated or filtered. These patients are typically hypoxaemic with exercise intolerance and are at high risk of paradoxical emboli to the brain and other organs. These malformations are most commonly seen in hereditary haemorrhagic telangiectasia (HHT) (Mb. Osler-Weber-Rendu syndrome). Nowadays, the generally accepted treatment strategy of first choice is embolization of the afferent arteries to the arteriovenous malformations. It is a minimally invasive procedure and at the same time a lung preserving treatment with a very high technical success, high effectiveness and low morbidity and mortality. Embolization prevents cerebral stroke and abscess as well as pulmonary haemorrhage and further raises the functional level. Embolization is a well-established method of treating PAVM, with a significant effect on oxygenation of the blood. Screening for PAVM in patients at risk is recommended, especially in patients with HHT.

Hyperdense artery sign on computed tomography in acute ischemic stroke

Despite the advent and growing availability of magnetic resonance imaging, the imaging modality of choice in the acute care of stroke patients in many institutions remains computed tomography. The hyperdense artery sign is the earliest marker of acute ischemic stroke. In this short review, we discuss the pathology, incidence, clinical aspects, imaging findings, significance and future questions that need to be addressed concerning this important sign.

Arterio-biliary fistula as rare complication of chemoradiation therapy for intrahepatic cholangiocarcinoma

Significant hemobilia due to arterio-biliary fistula is a very rare complication of chemoradiation therapy (CRT) for unresectable intrahepatic cholangiocarcinoma (ICC). Here we report a case of arterio-biliary fistula after CRT for unresectable ICC demonstrated by angiographic examinations. This fistula was successfully treated by endovascular embolization. Hemobilia is a rare complication, but arterio-biliary fistula should be considered after CRT of ICC.

Imaging of benign and malignant cystic pancreatic lesions and a strategy for follow up

Cystic lesions in a variety of organs are being increasingly recognized as an incidental finding on cross-sectional imaging. These lesions can be benign, premalignant or malignant. When these cystic lesions are small it can be difficult to characterize them radiologically. However, with appropriate clinical history and knowledge of typical imaging features of cystic pancreatic lesions this can enable accurate diagnosis and thus guide appropriate treatment. In this review, we provide an overview of the most common types of cystic lesions and their appearance on computer tomography, magnetic resonance imaging and ultrasound. We will also discuss the follow up and management strategies of these cystic lesions.

Percutaneous imaging-guided interventions for acute biliary disorders in high surgical risk patients

AIM: To evaluate the efficacy of percutaneous imaging-guided biliary interventions in the management of acute biliary disorders in high surgical risk patients.

METHODS: One hundred and twenty two patients underwent 139 percutaneous imaging-guided biliary interventions during the period between January 2007 to December 2009. The patients included 73 women and 49 men with a mean age of 61 years (range 35-90 years).

Fifty nine patients had acute biliary obstruction, 26 patients had acute biliary infection and 37 patients had abnormal collections. The procedures were performed under computed tomography (CT)- (73 patients), sonographic- (41 patients), and fluoroscopic-guidance (25 patients). Success rates and complications were determined. The χ² test with Yates’ correction for continuity was applied to compare between these procedures. A P value < 0.05 was considered significant.

RESULTS: The success rates for draining acute biliary obstruction under CT- , fluoroscopy- or ultrasound-guidance were 93.3%, 62.5% and 46.1%, respectively with significant P values (P = 0.026 and 0.002, respectively). In acute biliary infection, successful drainage was achieved in 22 patients (84.6%). The success rates in patients drained under ultrasound- and CT-guidance were 46.1% and 88.8%, respectively and drainage under CT-guidance was significantly higher (P = 0.0293). In 13 patients with bilomas, percutaneous drainage was successful in 11 patients (84.6%). Ten out of 12 cases with hepatic abscesses were drained with a success rate of 83.3%. In addition, the success rate of drainage in 12 cases with pancreatic pseudocysts was 83.3%. The reported complications were two deaths, four major and seven minor complications.

CONCLUSION: Percutaneous imaging-guided biliary interventions help to promptly diagnose and effectively treat acute biliary disorders. They either cure the disorders or relieve sepsis and jaundice before operations.

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented.

Diagnosis of subepithelial tumors in the upper gastrointestinal tract by endoscopic ultrasonography

Endoscopic ultrasonography (EUS) is the most accurate procedure for detecting and diagnosing subepithelial tumors, due to its higher sensitivity and specificity than other imaging modalities. EUS can characterize lesions by providing information on echogenic origin, size, borders, homogeneity, and the presence of echogenic or anechoic foci. Linear echoendoscopes, and recently also electronic radial echoendoscopes, can be used with color Doppler or power Doppler to assess the vascular signals from subepithelial masses, and thus permit the differentiation of vascular structures from cysts, as well as the assessment of the tumor blood supply. However, the diagnostic accuracy of EUS imaging alone has been shown to be low in subepithelial lesions with 3rd and 4th layers. It is also difficult to differentiate exactly between benign and malignant tumors and to gain an accurate picture of histology using EUS. On the other hands, EUS guided fine needle aspiration (EUS-FNA) can provide samples for cytologic or histologic analysis. Hypoechoic lesions of the 3rd and the 4th EUS layers, more than in 1 cm diameter are recommended, and histologic confirmation using endoscopic submucosal resection or EUS-FNA should be obtained when possible. Therefore, EUS-FNA plays an important role in the clinical management of subepithelial tumors. Furthermore improvements in endoscopic technology are expected to be more useful modalities in differential diagnosis and discrimination between benign and malignant subepithelial tumors.

Chemoradiation as definitive treatment for primary squamous cell cancer of the rectum

In this report, we present a case of advanced squamous cell cancer located in the rectum of a 78-year-old woman treated with chemoradiation with curative intent. The patient showed a complete clinical response to chemoradiation; multiple biopsies were performed at the site of the previous mass 5 mo after the end of treatment and histological examination showed no residual tumour in the specimens. Surgical intervention was avoided and the patient was free of disease 12 mo after the diagnosis of cancer. Primary chemoradiation should be considered as the treatment of choice for this rare malignancy.

Primary esophageal lymphoma in immunocompetent patients: Two case reports and literature review

Primary lymphoma that involves the esophagus is very rare, with fewer than 30 cases reported in the English-language literature. Non-Hodgkin lymphoma accounts for most of the cases. Esophageal lymphomas have varied radiological appearances, which poses diagnostic difficulty. We report two cases of histopathologically confirmed primary diffuse large B-cell esophageal lymphoma and describe their radiological features, and briefly review the literature.

Magnetic resonance imaging for acute pancreatitis

Acute pancreatitis is characterized by acute chemical injury of the pancreatic parenchyma and peripancreatic tissue. The increased frequency of death in acute pancreatitis is directly correlated with the degree and progress of pancreatic necrosis. Moreover, the occurrence of some local complications in acute pancreatitis, such as pancreatic hemorrhage, peripancreatic abscess or large pseudocyst, and pseudoaneurysm, could influence the choice of treatment for these patients. Magnetic resonance imaging (MRI) can be used to help evaluate the presence and degree of pancreatic necrosis, and is crucial for identifying complications of acute pancreatitis and predicting prognosis. The purpose of this article is to describe MRI techniques for acute pancreatitis, to review the spectrum of pancreatic and peripancreatic patterns, as well as to survey various complications secondary to acute pancreatitis on MRI. The role of MRI in the initial evaluation and staging of acute pancreatitis is emphasized.

Interventional management of tracheobronchial strictures

Tracheobronchial balloon dilation and stent placement have been well used in the treatment of patients with benign and/or malignant diseases. Balloon dilation is the first option in the treatment of benign airway stenosis. Although balloon dilation is simple and fast, recurrence rate is high. Stent placement promptly relieves acute airway distress from malignant extraluminal and intraluminal airway obstruction. Temporary stent placement may be an alternative for benign airway strictures refractory to balloon dilation. This article reviews the indications, pre-procedure evaluation, technique, outcomes and complications of balloon dilation and stent placement with regard to benign and malignant tracheobronchial stenoses.

Magnetic resonance cholangiopancreatography image enhancement for automatic disease detection

AIM: To sufficiently improve magnetic resonance cholangiopancreatography (MRCP) quality to enable reliable computer-aided diagnosis (CAD).

METHODS: A set of image enhancement strategies that included filters (i.e. Gaussian, median, Wiener and Perona-Malik), wavelets (i.e. contourlet, ridgelet and a non-orthogonal noise compensation implementation), graph-cut approaches using lazy-snapping and Phase Unwrapping MAxflow, and binary thresholding using a fixed threshold and dynamic thresholding via histogram analysis were implemented to overcome the adverse characteristics of MRCP images such as acquisition noise, artifacts, partial volume effect and large inter- and intra-patient image intensity variations, all of which pose problems in application development. Subjective evaluation of several popular pre-processing techniques was undertaken to improve the quality of the 2D MRCP images and enhance the detection of the significant biliary structures within them, with the purpose of biliary disease detection.

RESULTS: The results varied as expected since each algorithm capitalized on different characteristics of the images. For denoising, the Perona-Malik and contourlet approaches were found to be the most suitable. In terms of extraction of the significant biliary structures and removal of background, the thresholding approaches performed well. The interactive scheme performed the best, especially by using the strengths of the graph-cut algorithm enhanced by user-friendly lazy-snapping for foreground and background marker selection.

CONCLUSION: Tests show promising results for some techniques, but not others, as viable image enhancement modules for automatic CAD systems for biliary and liver diseases.