Positron emission tomography and magnetic resonance imaging combined with computed tomography in tumor volume delineation: A case report

BACKGROUND Accurate delineation of the target area for patients with hypopharyngeal cancer is the key to achieving an ideal radiotherapy effect.Since computed tomography(CT)alone can no longer meet the treatment needs,fusing CT images with magnetic resonance imaging(MRI)or positron emission tomography(PET)images can overcome the disadvantages of CT.Herein,we present a clinical case of hypopharyngeal cancer to delineate the tumor volume using combined MRI-CT and PET-CT fusion images to examine if they could accurately cover the tumor volume.CASE SUMMARY A 67-year-old male patient with hypopharyngeal carcinoma could not tolerate chemotherapy and surgery due to complicated health issues such as diabetic nephropathy and other underlying diseases.After multidisciplinary consultations,clinicians eventually agreed to undergo radiotherapy to control the progression of his tumor.He was examined by CT,MRI,and 18-fluorodeoxyglucose-PET for treatment planning,and CT images were fused with PET and MRI images while delineating tumor volume.CONCLUSION The image fusion of MRI-CT and PET-CT has both advantages and disadvantages.Compared with CT images alone,the combination of MRI-CT and PET-CT fusion images can precisely cover the gross tumor volume in hypopharyngeal carcinoma and avoid overestimation or incomplete coverage of tumor volume.

Computed tomography, magnetic resonance imaging, and Fdeoxyglucose positron emission computed tomography/computed tomography findings of alveolar soft part sarcoma with calcification in the thigh: A case report

BACKGROUND Alveolar soft part sarcoma(ASPS)is an extremely rare malignant sarcoma,accounting for less than 1%of all soft-tissue sarcomas.However,limited information is available on multimodal imaging[computed tomography(CT),magnetic resonance imaging(MRI),and positron emission computed tomography/computed tomography(PET/CT)]of ASPS.CASE SUMMARY This study reports a case of a 35-year-old female patient with ASPS of the left thigh with lung metastasis.The patient presented with a 1-year history of a palpable mass in the lower extremity,which exhibited rapid growth for 3 wk.CT,MRI,and F-deoxyglucose PET/CT examinations were performed.CT showed a slightly hypodense or isodense mass with patchy calcifications.On MRI examination,the mass manifested hyperintensity on T1-weighted,T2-weighted,and diffusion-weighted images with some signal voids.PET/CT images demonstrated an intensely hypermetabolic mass in the left thigh and hypermetabolic nodules in lungs.CONCLUSION ASPS should be considered as a possible diagnosis when a slow-growing mass is detected in the soft tissue of the extremities,with hyperintensity and numerous signal voids on T1-weighted,T2-weighted,and diffusion-weighted images and intense F-deoxyglucose uptake on PET/CT.ASPS can have calcifications on CT.

Clinical significance of prostate 18F-labelled fluorodeoxyglucose uptake on positron emission tomography/computed tomography:A five-year review

AIM To determine the significance and need for investigation of incidental prostatic uptake in men undergoing ^(18)F-labelled fluorodeoxyglucose(^(18)F-FDG) positron emission tomography/computed tomography(PET/CT) for other indications.METHODS Hospital databases were searched over a 5-year period for patients undergoing both PET/CT and prostate magnetic resonance imaging(MRI). For the initial analysis, the prostate was divided into six sectors and suspicious or malignant sectors were identified using MRI and histopathology reports respectively. Maximum and mean ^(18)F-FDG standardised uptake values were measured in each sector by an investigator blinded to the MRI and histopathology findings. Two agematched controls were selected per case. Results were analysed using a paired t-test and one-way ANOVA. For the second analysis, PET/CT reports were searched for prostatic uptake reported incidentally and these patients were followed up. RESULTS Over a 5-year period, 15 patients underwent both PET/CT and MRI and had biopsy-proven prostate cancer.Malignant prostatic sectors had a trend to higher ^(18)F-FDG uptake than benign sectors, however this was neither clinically nor statistically significant(3.13 ±0.58 vs 2.86 ± 0.68, P > 0.05). ^(18)F-FDG uptake showed no correlation with the presence or histopathological grade of tumour. ^(18)F-FDG uptake in cases with prostate cancer was comparable to that from age-matched controls. Forty-six(1.6%) of 2846 PET/CTs over a 5-year period reported incidental prostatic uptake. Of these, 18(0.6%) were investigated by PSA, 9(0.3%)were referred to urology, with 3(0.1%) undergoing MRI and/or biopsy. No cases of prostate cancer were diagnosed in patients with incidental ^(18)F-FDG uptake in our institute over a 5-year period.CONCLUSION ^(18)F-FDG uptake overlaps significantly between malignant and benign prostatic conditions. Subsequent patient management was not affected by the reporting of incidental focal prostatic uptake in this cohort.

Utility of positron emission tomography-magnetic resonance imaging in musculoskeletal imaging

Differentiation between neoplastic and nonneoplastic conditions magnetic resonance imaging(MRI) has established itself as one of the key clinical tools in evaluation of musculoskeletal pathology. However, MRI still has several key limitations which require supplemental information from additional modalities to complete evaluation of various disorders. This has led to the development hybrid positron emission tomography(PET)-MRI which is rapidly evolving to address key clinical questions by using the morphological strengths of MRI and functional information of PET imaging. In this article, we aim to review physical principles and techniques of PET-MRI and discuss clinical utility of functional information obtained from PET imaging and structural information obtained from MRI imaging for the evaluation of musculoskeletal pathology. More specifically, this review highlights the role of PET-MRI in musculoskeletal oncology including initial diagnosis and staging, treatment planning and posttreatment follow-up. Also we will review utility of PET-MRI in evaluating musculoskeletal infections(especially in the immunocompromised and diabetics) and inflammatory condition. Additionally, common pitfalls of PET-MRI will be addressed.

Liver metastases:Contrast-enhanced ultrasound compared with computed tomography and magnetic resonance

The development of ultrasound contrast agents with excellent tolerance and safety profiles has notably improved liver evaluation with ultrasound(US)for several applications,especially for the detection of metastases.In particular,contrast enhanced ultrasonography(CEUS)allows the display of the parenchymal microvasculature,enabling the study and visualization of the enhancement patterns of liver lesions in real time and in a continuous manner in all vascular phases,which is similar to contrast-enhanced computed tomography(CT)and contrast-enhanced magnetic resonance imaging.Clinical studies have reported that the use of a contrast agent enables the visualization of more metastases with significantly improved sensitivity and specificity compared to baseline-US.Furthermore,studies have shown that CEUS yields sensitivities comparable to CT.In this review,we describe the state of the art of CEUS for detecting colorectal liver metastases,the imaging features,the literature reports of metastases in CEUS as well as its technique,its clinical role and its potential applications.Additionally,the updated international consensus panel guidelines are reported in this review with the inherent limitations of this technique and best practice experiences.

Fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging of uterine leiomyosarcomas： 2 cases report

Uterine leiomyosarcoma is an uncommon malignant neoplasm of smooth muscle origination and is associated with a poor prognosis. We report two cases of uterine leiomyosarcoma that presented with pulmonary metastases.2-deoxy-2-（18F）fluorodeoxyglucose （FDG） positron emission tomography （PET）/computed tomography （CT） was performed to identify the primary carcinoma and found the focus located in the uterus. The follow-up magnetic resonance imaging （MRI） confirmed the diagnosis was uterine leiomyosarcoma.

Combination of 18F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging is an optimal way to evaluate rheumatoid arthritis in rats dynamically

Background Rheumatoid arthritis （RA） is a chronic,systemic autoimmune inflammatory disorder.Many methods have been used to observe the progress of RA.The purpose of this study was to observe the progress of RA in rats with 18F-fluorodeoxyglucose （FDG） positron emission tomography/computed tomography （PET/CT）,magnetic resonance （MR） imaging and arthritis score,and analyze the relationships among different methods in evaluation of RA.Methods Sixteen healthy Sprague Dawley （SD） rats about 8-week old were randomly assigned to a RA group and a control group.Bovine type Ⅱ emulsified incomplete Freud＇s adjuvant was used to induce arthritis in the RA group.Arthritis score of the rats in two groups were recorded,and 18F-FDG PET/CT,MR imaging were performed both on the corresponding rats every 3 days.All the rats were sacrificed at week 5,and histopathological examination was performed on rat knees stained with haematoxylin and eosin.Results The arthritis score and the standard uptake value （SUV） of knee joints in RA rats increased with the progression of arthritis gradually.Both peaks of arthritis score and SUV appeared at 21 days after the first immune injection,then the arthritis score and SUV of knee joints decreased slowly.The arthritis scores of knee joints in RA rats were positively correlated with their SUV changes.The MR images were confirmed by the histopathological studies.Conclusion PET/CT can detect the earliest molecular metabolism changes of RA,and MR imaging can follow up the dynamical anatomical changes of RA,all of which indicated that PET/CT and MR imaging may be applied as useful tools to monitor the progress of RA.

Role of advanced magnetic resonance imaging in the assessment of malignancies of the mediastinum

In the new era of functional magnetic resonance imaging(MRI), the utility of chest MRI is increasing exponentially due to several advances, including absence of ionizing radiation, excellent tissue contrast and high capability for lesion characterization and treatment monitoring. The application of several of these diagnostic weapons in a multiparametric fashion enables to better characterize thymic epithelial tumors and other mediastinal tumoral lesions, accurate assessment of the invasion of adjacent structures and detection of pathologic lymph nodes and metastasis. Also, "do not touch lesions" could be identified with the associated impact in the management of those patients. One of the hotspots of the multiparametric chest MR is its ability to detect with acuity early response to treatment in patients with mediastinal malignant neoplasms. This has been related with higher rates of overall survival and progression free survival.Therefore, in this review we will analyze the current functional imaging techniques available(18 F-Fluorodeoxiglucose positron emission tomography/computed tomography, diffusion-weighted imaging, dynamic contrast-enhanced MRI, diffusion tensor imaging and MR spectroscopy) for the evaluation of mediastinal lesions, with a focus in their correct acquisition and post-processing. Also, to review the clinical applications of these techniques in the diagnostic approach of benign and malignant conditions of the mediastinum.

Colorectal cancer: Parametric evaluation of morphological,functional and molecular tomographic imaging

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

^(18)F-FDG PET/CT in differentiating malignant from benign origins of obstructive jaundice

BACKGROUND： The various origins of obstructive jaundice make the diagnosis of the disease difficult. This study was undertaken to evaluate the role of 18F-FDG PET/CT in differentiating malignant from benign origins of obstructive jaundice and to quantify the added value of 18F-FDG PET/CT over conventional imaging（enhanced CT and/or MRI）.METHODS： Eighty-five patients with obstructive jaundice who underwent 18F-FDG PET/CT within 2 weeks after enhanced CT and/or MRI were reviewed retrospectively. All 18F-FDG PET/CT images were independently evaluated by 2 nuclear medicine physicians who were unaware of other imaging data; differences were resolved by consensus of the physicians. All conventional imaging interpretations, according to the medical records, were reviewed by 2 radiologists to determine the potential value. Final diagnoses were based on histological or surgical findings.RESULTS： Sixty-six patients were diagnosed with malignancies, and 19 patients with benign lesions. The maximum standardized uptake values for malignant and benign lesions causing biliary obstruction were 8.2±4.4 and 4.0±5.0, respectively（P〈0.05）. The sensitivity, specificity, and overall accuracy for differentiating malignant from benign origins with 18F-FDG PET/CT were 86.4%（57/66）, 73.7%（14/19）, and 83.5%（71/85）, respectively. 18F-FDG PET/CT in conjunction with conventional imaging changed the sensitivity, specificity, and overall accuracy of conventional imaging alone from 75.8%（50/66） to 95.5%（63/66）（P〈0.05）, 68.4%（13/19） to 57.9%（11/19）（P〉0.05）, and 74.1%（63/85） to 87.1%（74/85）（P〈0.05）, respectively.CONCLUSIONS： 18F-FDG PET/CT is of great value in differentiating malignant from benign origins of obstructive jaundice and is a useful adjuvant to conventional imaging. 18F-FDG PET/CT should be recommended for further etiological clarification.

Multimodal imaging in the diagnosis of bone giant cell tumors:A retrospective study

BACKGROUND Giant cell tumor of bone is a locally aggressive and rarely metastasizing tumor,and also a potential malignant tumor that may develop into a primary malignant giant cell tumor.AIM To evaluate the role of multimodal imaging in the diagnosis of giant cell tumors of bone.METHODS The data of 32 patients with giant cell tumor of bone confirmed by core-needle biopsy or surgical pathology at our hospital between March 2018 and March 2023 were retrospectively selected.All the patients with giant cell tumors of the bone were examined by X-ray,computed tomography(CT)and magnetic resonance imaging(MRI),and 7 of them were examined by positron emission tomography(PET)-CT.RESULTS X-ray imaging can provide overall information on giant cell tumor lesions.CT and MRI can reveal the characteristics of the internal structure of the tumor as well as the adjacent relationships of the tumor,and these methods have unique advantages for diagnosing tumors and determining the scope of surgery.PET-CT can detect small lesions and is highly valuable for identifying benign and malignant tumors to aid in the early diagnosis of metastasis.CONCLUSION Multimodal imaging plays an important role in the diagnosis of giant cell tumor of bone and can provide a reference for the treatment of giant cell tumors.

Role of advanced imaging techniques in the evaluation of oncological therapies in patients with colorectal liver metastases

In patients with colorectal liver metastasis(CRLMs)unsuitable for surgery,oncological treatments,such as chemotherapy and targeted agents,can be performed.Cross-sectional imaging[computed tomography(CT),magnetic resonance imaging(MRI),18-fluorodexoyglucose positron emission tomography with CT/MRI]evaluates the response of CRLMs to therapy,using post-treatment lesion shrinkage as a qualitative imaging parameter.This point is critical because the risk of toxicity induced by oncological treatments is not always balanced by an effective response to them.Consequently,there is a pressing need to define biomarkers that can predict treatment responses and estimate the likelihood of drug resistance in individual patients.Advanced quantitative imaging(diffusionweighted imaging,perfusion imaging,molecular imaging)allows the in vivo evaluation of specific biological tissue features described as quantitative parameters.Furthermore,radiomics can represent large amounts of numerical and statistical information buried inside cross-sectional images as quantitative parameters.As a result,parametric analysis(PA)translates the numerical data contained in the voxels of each image into quantitative parameters representative of peculiar neoplastic features such as perfusion,structural heterogeneity,cellularity,oxygenation,and glucose consumption.PA could be a potentially useful imaging marker for predicting CRLMs treatment response.This review describes the role of PA applied to cross-sectional imaging in predicting the response to oncological therapies in patients with CRLMs.

Imaging features of retinal hemangioblastoma:A case report

BACKGROUND Hemangioblastoma typically occurs in the cerebellum,spinal cord,and central nervous system.However,in rare cases,it could occur in the retina or optic nerve.The prevalence of retinal hemangioblastoma is 1 in 73080,and it occurs either alone or as the manifestation of von Hippel Lindau(VHL)disease.Here,we reported a rare case with the imaging features of retinal hemangioblastoma without VHL syndrome,along with the relevant literature review.CASE SUMMARY A 53-year-old man had progressive swelling,pain and blurred vision in the left eye without obvious inducement for 15 d.Ultrasonography revealed a possible optic nerve head melanoma.Computed tomography(CT)showed punctate calcification on the posterior wall of the left eye ring and small patchy soft tissue density in the posterior part of the eyeball.Magnetic resonance imaging showed slightly hyperintense signal on T1-weighted images and slightly hypointense-toisointense signal on T2-weighted images at the medial and posterior edges of the left eyeball,a significant enhancement was observed in the contrast-enhanced scans.Positron emission tomography/CT fusion images showed that the glucose metabolism of the lesion was normal.Pathology was consistent with hemangioblastoma.CONCLUSION Early identification of retinal hemangioblastoma based on imaging features is of great value for its personalized treatment.

Current imaging strategies for the evaluation of uterine cervical cancer

Uterine cervical cancer still remains an important socioeconomic issue because it largely affects women of reproductive age.Prognosis is highly depended on extent of the disease at diagnosis and,therefore,accurate staging is crucial for optimal management.Cervical cancer is clinically staged,according to International Federation of Gynecology and Obstetrics guidelines,but,currently,there is increased use of cross sectional imaging modalities [computed tomography(CT),magnetic resonance imaging(MRI),positron emission tomography-CT(PET-CT)] for the study of important prognostic factors like tumor size,parametrial invasion,endocervical extension,pelvic side wall or adjacent/distal organs involvement and lymph node status.Imaging indications also include cervical cancer follow-up,evaluation of tumor response to treatment and selection of suitable candidates for less radical surgeries like radical trachelectomy for fertility preservation.The preferred imaging method for local cervical cancer evaluation is MRI;CT is equally effective for evaluation of extrauterine spread of the disease.PETCT shows high diagnostic performance for the detection of tumor relapse and metastatic lymph nodes.The aim of this review is to familiarize radiologists with the MRI appearance of cervical carcinoma and to discuss the indications of cross sectional imaging during the course of the disease in patients with cervical carcinoma.

Autoimmune pancreatitis in the context of IgG4-related disease:Review of imaging findings

Current understanding of autoimmune pancreatitis(AIP) recognizes a histopathological subtype of the disease to fall within the spectrum of IgG4-related disease.Along with clinical,laboratory,and histopathological data,imaging plays an important role in the diagnosis and management of AIP,and more broadly,within the spectrum of IgG4-related disease.In addition to the defined role of imaging in consensus diagnostic protocols,an array of imaging modalities can provide complementary data to address specific clinical concerns.These include contrast-enhanced computed tomography(CT) and magnetic resonance(MR) imaging for pancreatic parenchymal lesion localization and characterization,endoscopic retrograde and magnetic resonance cholangiopancreatography(ERCP and MRCP) to assess for duct involvement,and more recently,positron emission tomography(PET) imaging to assess for extra-pancreatic sites of involvement.While the imaging appearance of AIP varies widely,certain imaging features are more likely to represent AIP than alternate diagnoses,such as pancreatic cancer.While nonspecific,imaging findings which favor a diagnosis of AIP rather than pancreatic cancer include:delayed enhancement of affected pancreas,mild dilatation of the main pancreatic duct over a long segment,the "capsule" and "penetrating duct" signs,and responsiveness to corticosteroid therapy.Systemic,extra-pancreatic sites of involvement are also often seen in AIP and IgG4-related disease,and typically respond to corticosteroid therapy.Imaging by CT,MR,and PET also play a role in the diagnosis and monitoring after treatment of involved sites.

Imaging diagnosis of pancreatic cancer:A state-of-the-art review

Pancreatic cancer(PC)remains one of the deadliest cancers worldwide,and has a poor,five-year survival rate of 5%.Although complete surgical resection is the only curative therapy for pancreatic cancer,less than20%of newly-diagnosed patients undergo surgical resection with a curative intent.Due to the lack of early symptoms and the tendency of pancreatic adenocarcinoma to invade adjacent structures or to metastasize at an early stage,many patients with pancreatic cancer already have advanced disease at the time of their diagnosis and,therefore,there is a high mortality rate.To improve the patient survival rate,early detection of PC is critical.The diagnosis of PC relies on computed tomography(CT)and/or magnetic resonance imaging(MRI)with magnetic resonance cholangiopancreatography(MRCP),or biopsy or fine-needle aspiration using endoscopic ultrasound(EUS).Although multi-detector row computed tomography currently has a major role in the evaluation of PC,MRI with MRCP facilitates better detection of tumors at an early stage by allowing a comprehensive analysis of the morphological changes of the pancreas parenchyma and pancreatic duct.The diagnosis could be improved using positron emission tomography techniques in special conditions in which CT and EUS are not completely diagnostic.It is essential for clinicians to understand the advantages and disadvantages of the various pancreatic imaging modalities in order to be able to make optimal treatment and management decisions.Our study investigates the current role and innovative techniques of pancreatic imaging focused on the detection of pancreatic cancer.

Imaging of multiple myeloma: Current concepts

Medical imaging is of crucial importance for diagnosis and initial staging as well as for differentiation of multiple myeloma(MM)from other monoclonal plasma cell diseases.Conventional radiography represents the reference standard for diagnosis of MM due to its wide availability and low costs despite its known limitations such as low sensitivity,limited specificity and its inability to detect extraosseous lesions.Besides conventional radiography,newer cross-sectional imaging modalities such as whole-body low-dose computed tomography(CT),whole-body magnetic resonance imaging(MRI)and18F-fluorodeoxyglucose(FDG)positron emission tomography(PET)/CT are available for the diagnosis of osseous and extraosseous manifestations of MM.Whole-body low-dose CT is used increasingly,replacing conventional radiography at selected centers,due to its higher sensitivity for the detection of osseous lesions and its ability to diagnose extraosseous lesions.The highest sensitivity for both detection of bone marrow disease and extraosseous lesions can be achieved with whole-body MRI and18F-FDG PET/CT.According to current evidence,MRI is the most sensitive method for initial staging while18F-FDG PET/CT allows monitoring of treatment of MM.There is an evolving role for assessment of treatment response using newer MR imagingtechniques.Future studies are needed to further define the exact role of the different imaging modalities for individual risk stratification and therapy monitoring.

Feasibility of prostatectomy without prostate biopsy in the era of new imaging technology and minimally invasive techniques

BACKGROUND Routinely, after receiving prostate specific antigen (PSA) testing and digital rectum examination, patients with suspected prostate cancer are required to undergo prostate biopsy. However, the ability of ultrasound-guided prostate biopsy to detect prostate cancer is limited. Nowadays, a variety of diagnostic methods and more sensitive diagnostic methods, such as multi-parameter prostate magnetic resonance imaging (mpMRI) and prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) can be applied clinically. Furthermore, laparoscopic/robot-assisted prostatectomy is also a safe and effective procedure for the treatment of benign prostatic hyperplasia. So maybe it is time to reconsider the necessary to perform prostate biopsy before radical prostatectomy. AIM To explore the feasibility of radical prostatectomy without prostate biopsy in the era of new imaging technology and minimally invasive techniques. METHODS From June 2014 to November 2018, 11 cases of laparoscopic radical prostatectomy without prostate biopsy were performed at the three tertiary medical centers involved in this study. All patients received prostate magnetic resonance imaging and prostate cancer was suspected, including six patients with positive 68Ga- PSMA PET/CT results. Laparoscopic radical prostatectomy and pelvic lymph node dissection were performed for all patients. RESULTS All surgeries were accomplished successfully. The mean age was 69 ± 7.7 year, the mean body mass index was 24.7 ± 1.6 kg/m2, the range of serum PSA was 4.3 to >1000 ng/mL, and the mean prostate volume was 40.9 ± 18.3 mL. The mean operative time was 96 ± 23.3 min, the mean estimated blood loss was 90 ± 90.9 mL, and the median duration of catheter placement was 14 d. The final pathology confirmed that all specimens were prostate cancer except one case of benign prostatic hyperplasia. No major complications occurred in 90 d postoperatively. CONCLUSION The current practice of mandating a prostatic biopsy before prostatectomy should be reconsidered in the era of new imaging technology and minimally invasive techniques. Radical prostatectomy could be carried out without the evidence of malignancy. Large-sample randomized controlled trials are definitely required to confirm the feasibility of this new concept.

Pancreatic fluid collections: What is the ideal imaging technique?

Pancreatic fluid collections(PFCs) are seen in up to 50% of cases of acute pancreatitis. The Revised Atlanta classification categorized these collections on the basis of duration of disease and contents, whether liquid alone or a mixture of fluid and necrotic debris. Management of these different types of collections differs because of the variable quantity of debris; while patients with pseudocysts can be drained by straight-forward stent placement, walledoff necrosis requires multi-disciplinary approach. Differentiating these collections on the basis of clinical severity alone is not reliable, so imaging is primarily performed. Contrast-enhanced computed tomography is the commonly used modality for the diagnosis and assessment of proportion of solid contents in PFCs; however with certain limitations such as use of iodinated contrast material especially in renal failure patients and radiation exposure. Magnetic resonance imaging(MRI) performs better than computed tomography(CT) in characterization of pancreatic/peripancreatic fluid collections especially for quantification of solid debris and fat necrosis(seen as fat density globules), and is an alternative in those situations where CT is contraindicated. Also magnetic resonance cholangiopancreatography is highly sensitive for detecting pancreatic duct disruption and choledocholithiasis. Endoscopic ultrasound is an evolving technique with higher reproducibility for fluid-to-debris component estimation with the added advantage of being a single stage procedure for both diagnosis(solid debris delineation) and management(drainage of collection) in the same sitting. Recently role of diffusion weighted MRI and positron emission tomography/CT with ^(18)F-FDG labeled autologous leukocytes is also emerging for detection of infection noninvasively. Comparative studies between these imaging modalities are still limited. However we look forward to a time when this gap in literature will be fulfilled.

Imaging of pancreatic ductal adenocarcinoma: State of the art

Significant advances in imaging technology have changed the management of pancreatic cancer. In computed tomography (CT), this has included development of multidetector row, rapid, thin-section imaging that has also facilitated the advent of advanced reconstructions, which in turn has offered new perspectives from which to evaluate this disease. In magnetic resonance imaging, advances including higher field strengths, thin-section volumetric acquisitions, diffusion weighted imaging, and liver specific contrast agents have also resulted in new tools for diagnosis and staging. Endoscopic ultrasound has resulted in the ability to provide high-resolution imaging rivaling intraoperative ultrasound, along with the ability to biopsy via real time imaging suspected pancreatic lesions. Positron emission tomography with CT, while still evolving in its role, provides whole body staging as well as the unique imaging characteristic of metabolic activity to aid disease management. This article will review these modalities in the diagnosis and staging of pancreatic cancer.