MR imaging of pancreatic lesions. Comparison of manganese-DPDP and gadolinium chelate

Novel Salinomycin-Based Paramagnetic Complexes-First Evaluation of Their Potential Theranostic Properties

Combining therapeutic with diagnostic agents (theranostics) can revolutionize the course of malignant diseases. Chemotherapy, hyperthermia, or radiation are used together with diagnostic methods such as magnetic resonance imaging (MRI). In contrast to conventional contrast agents (CAs), which only enable non-specific visualization of tissues and organs, the theranostic probe offers targeted diagnostic imaging and therapy simultaneously.

METHODS

Novel salinomycin (Sal)-based theranostic probes comprising two different paramagnetic metal ions, gadolinium(III) (Gd(III)) or manganese(II) (Mn(II)), as signal emitting motifs for MRI were synthesized and characterized by elemental analysis, infrared spectral analysis (IR), electroparamagnetic resonance (EPR), thermogravimetry (TG) differential scanning calorimetry (DSC) and electrospray ionization mass spectrometry (ESI-MS). To overcome the water insolubility of the two Sal-complexes, they were loaded into empty bacterial ghosts (BGs) cells as transport devices. The potential of the free and BGs-loaded metal complexes as theranostics was evaluated by in vitro relaxivity measurements in a high-field MR scanner and in cell culture studies.

RESULTS

Both the free Sal-complexes (Gd(III) salinomycinate (Sal-Gd(III) and Mn(II) salinomycinate (Sal-Mn(II)) and loaded into BGs demonstrated enhanced cytotoxic efficacy against three human tumor cell lines (A549, SW480, CH1/PA-1) relative to the free salinomycinic acid (Sal-H) and its sodium complex (Sal-Na) applied as controls with IC₅₀ in a submicromolar concentration range. Moreover, Sal-H, Sal-Gd(III), and Sal-Mn(II) were able to induce perturbations in the cell cycle of treated colorectal and breast human cancer cell lines (SW480 and MCF-7, respectively). The relaxivity (r₁) values of both complexes as well as of the loaded BGs, were higher or comparable to the relaxivity values of the clinically applied contrast agents gadopentetate dimeglumine and gadoteridol.

CONCLUSION

This research is the first assessment that demonstrates the potential of Gd(III) and Mn(II) complexes of Sal as theranostic agents for MRI. Due to the remarkable selectivity and mode of action of Sal as part of the compounds, they could revolutionize cancer therapy and allow for early diagnosis and monitoring of therapeutic follow-up.

A Brucite-Like Mixed-Valent Cluster Capped by [MnIIIp-tBu-calix[4]arene]− Moieties

p-tBu-calix[4]arene (H4TBC[4]) has proven to be an incredibly versatile ligand for the synthesis of 3d- and 3d/4f- clusters, in particular those containing mixed-valent Mn ions. These are of interest to the magnetochemist for the diversity of magnetic behaviours that can be shown, along with a huge variety of nuclearities and topologies accessible, which allow one to outline magneto-structural correlations and a quantitative understanding of their properties. This contribution reports the synthesis, analysis and magnetic properties of a Brucite-like Mn-oxo/hydroxo octanuclear fragment encapsulated within/capped by four [MnIII-TBC[4]]− moieties. A diol coligand in the reaction mixture plays a seemingly important role in determining the outcome, though it is not incorporated in the final structure.

Quantitative phase imaging of stromal prognostic markers in pancreatic ductal adenocarcinoma

New quantitative prognostic markers are needed for improved pancreatic ductal adenocarcinoma (PDAC) prognosis. Second harmonic generation microscopy has been used to show that collagen fiber alignment in PDAC is a negative prognostic factor. In this work, a series of PDAC and normal adjacent tissue (NAT) biopsies were imaged with spatial light interference microscopy (SLIM). Quantitative analysis performed on the biopsy SLIM images show that PDAC fiber structures have lower alignment per unit length, narrower width, and are longer than NAT controls. Importantly, fibrillar collagen in PDAC shows an inverse relationship between survival data and fiber width and length (p < 0.05).

Manganese oxide-carbon quantum dots nano-composites for fluorescence/magnetic resonance (T1) dual mode bioimaging, long term cell tracking, and ROS scavenging

Multimodal long-term imaging probes with capability of extracting complementary information are highly important in biomedical engineering for disease diagnosis and monitoring of therapeutics distribution. However, most of the theranostics probes used are transient and have inherent problem of toxicity mostly related to generation of free radicals. In current study, a simple microwave assisted synthesis of multimodal imaging nanoprobe (T1 contrast in MR/fluorescence) is reported via doping carbon quantum dots into manganese oxide nanoparticles. The nanostructures were characterized by US-Vis spectroscopy, fluorescence spectroscopy, FTIR, Raman spectroscopy, TEM, XRD, AFM and XPS. The average particle size was observed to be around 20-40 nm with a height of 7-9 nm and approximate quantum yield of 0.23. The nanostructures were useful for bio imaging and cell tracking via fluorescence microscopy up to 12 generations with nominal cytotoxicity. The material was capable of scavenging free radicals from cellular microenvironment and downregulate gene expression of free radical scavenging enzymes. The material has significant relaxivity (r1) value of 3.98 mM^-1.sec^-1 at 1.5 T. It was also observed to create significant contrast with high circulation time (30 min) and renal clearance property. The histological analysis of kidney and liver sections were observed to have no significant toxicity from the nanostructure.

Manganese-Enhanced Magnetic Resonance Imaging: Overview and Central Nervous System Applications With a Focus on Neurodegeneration

Manganese-enhanced magnetic resonance imaging (MEMRI) rose to prominence in the 1990s as a sensitive approach to high contrast imaging. Following the discovery of manganese conductance through calcium-permeable channels, MEMRI applications expanded to include functional imaging in the central nervous system (CNS) and other body systems. MEMRI has since been employed in the investigation of physiology in many animal models and in humans. Here, we review historical perspectives that follow the evolution of applied MRI research into MEMRI with particular focus on its potential toxicity. Furthermore, we discuss the more current in vivo investigative uses of MEMRI in CNS investigations and the brief but decorated clinical usage of chelated manganese compound mangafodipir in humans.

Gd(III)-Dithiolane Gold Nanoparticles for T1-Weighted Magnetic Resonance Imaging of the Pancreas

Pancreatic adenocarcinoma has a 5 year survival of approximately 3% and median survival of 6 months and is among the most dismal of prognoses in all of medicine. This poor prognosis is largely due to delayed diagnosis where patients remain asymptomatic until advanced disease is present. Therefore, techniques to allow early detection of pancreatic adenocarcinoma are desperately needed. Imaging of pancreatic tissue is notoriously difficult, and the development of new imaging techniques would impact our understanding of organ physiology and pathology with applications in disease diagnosis, staging, and longitudinal response to therapy in vivo. Magnetic resonance imaging (MRI) provides numerous advantages for these types of investigations; however, it is unable to delineate the pancreas due to low inherent contrast within this tissue type. To overcome this limitation, we have prepared a new Gd(III) contrast agent that accumulates in the pancreas and provides significant contrast enhancement by MR imaging. We describe the synthesis and characterization of a new dithiolane-Gd(III) complex and a straightforward and scalable approach for conjugation to a gold nanoparticle. We present data that show the nanoconjugates exhibit very high per particle values of r1 relaxivity at both low and high magnetic field strengths due to the high Gd(III) payload. We provide evidence of pancreatic tissue labeling that includes MR images, post-mortem biodistribution analysis, and pancreatic tissue evaluation of particle localization. Significant contrast enhancement was observed allowing clear identification of the pancreas with contrast-to-noise ratios exceeding 35:1.

Development of manganese-based nanoparticles as contrast probes for magnetic resonance imaging

MRI is one of the most important imaging tools in clinics. It interrogates nuclei of atoms in a living subject, providing detailed delineation with high spatial and temporal resolutions. To compensate the innate low sensitivity, MRI contrast probes were developed and widely used. These are typically paramagnetic or superparamagnetic materials, functioning by reducing relaxation times of nearby protons. Previously, gadolinium(Gd)-based T₁ contrast probes were dominantly used. However, it was found recently that their uses are occasionally associated with nephrogenic system fibrosis (NSF), which suggests a need of finding alternatives. Among the efforts, manganese-containing nanoparticles have attracted much attention. By careful engineering, manganese nanoparticles with comparable r₁ relaxivities can be yielded. Moreover, other functionalities, be a targeting motif, a therapeutic agent or a second imaging component, can be loaded onto these nanoparticles, resulting in multifunctional nanoplatforms.

Manganese-enhanced magnetic resonance imaging

Manganese-enhanced magnetic resonance imaging (MEMRI) relies on contrasts that are due to the shortening of the T (1) relaxation time of tissue water protons that become exposed to paramagnetic manganese ions. In experimental animals, the technique combines the high spatial resolution achievable by MRI with the biological information gathered by tissue-specific or functionally induced accumulations of manganese. After in vivo administration, manganese ions may enter cells via voltage-gated calcium channels. In the nervous system, manganese ions are actively transported along the axon. Based on these properties, MEMRI is increasingly used to delineate neuroanatomical structures, assess differences in functional brain activity, and unravel neuronal connectivities in both healthy animals and models of neurological disorders. Because of the cellular toxicity of manganese, a major challenge for a successful MEMRI study is to achieve the lowest possible dose for a particular biological question. Moreover, the interpretation of MEMRI findings requires a profound knowledge of the behavior of manganese in complex organ systems under physiological and pathological conditions. Starting with an overview of manganese pharmacokinetics and mechanisms of toxicity, this chapter covers experimental methods and protocols for applications in neuroscience.

Secretin-stimulated multi-detector CT versus mangafodipir trisodium-enhanced MR imaging plus MRCP in characterization of non-metastatic solid pancreatic lesions

BACKGROUND AND AIM

Our study was aimed to compare multiphasic multi-detector computed tomography after secretin stimulation and mangafodipir trisodium-enhanced magnetic resonance imaging plus MR cholangiopancreatography in the characterization of solid pancreatic lesions.

PATIENTS AND METHODS

Forty patients with ultrasound diagnosis of solid pancreatic lesion prospectively underwent both multi-detector computed tomography and magnetic resonance imaging. Three minutes after intravenous administration of secretin, post-contrast computed tomography scans were performed 40, 80, and 180 s after contrast medium injection. MR protocol included axial/coronal, thin/thick-slab, single-shot T2 w sequences and axial/coronal T1 w breath-hold spoiled gradient-echo images before and 30-40 min after intravenous infusion of manganese dipyri-doxal diphosphate. Different observers blindly evaluated the ability of computed tomography and magnetic resonance imaging to characterize focal pancreatic lesions. Surgery, biopsy, and/or follow-up were considered as our diagnostic gold standard.

RESULTS

Thirty-five focal pancreatic lesions (adenocarcinoma, n=18; focal chronic pancreatitis, n=4; endocrine tumor, n=6; metastasis, n=1; cystic tumor, n=3; indeterminate cystic lesions, n=3) were present in 34 patients since the remaining 6 subjects showed no pathological finding. Both multi-detector computed tomography and magnetic resonance imaging showed a statistically significant correlation with the gold standard and between themselves in the characterization of 29 solid lesions of the pancreas (p<0.05).

CONCLUSION

Both imaging techniques well correlate to final diagnosis of non-metastatic solid pancreatic lesions and particularly of adenocarcinomas with a slight advantage for mangafodipir trisodium-enhanced magnetic resonance imaging plus MR cholangiopancreatography.

Screening of high-risk families for pancreatic cancer

PURPOSE OF REVIEW

To discuss how to recognise and manage high-risk individuals.

RECENT FINDINGS

Publication of initial results of screening for pancreatic cancer from US centres. Several masses and premalignant lesions have been detected, but the detection of the first pancreatic cancer through an organised study of screening has yet to be published. There has been progress in risk stratification; the role of diabetes in predisposing for cancer has been characterised and molecular modalities have been published which could be used in conjunction with imaging in a screening programme. A mutation in the palladin gene was found to segregate with the disease in a family with a clear predisposition for pancreatic cancer, though this has yet to be found in other such kindreds.

SUMMARY

Significant challenges remain to be solved in screening for early pancreatic cancer. Risk stratification needs to be improved and high-risk patients included in research-based screening programmes. It will be impossible to confirm that screening can detect cancers early enough for curative treatment until the results of these prospective studies become available.

Pancreatic adenocarcinoma

Adenocarcinoma is the most common malignant pancreatic tumor, affecting the head of the pancreas in 60-70% of cases. By the time of diagnosis, at least 80% of tumors are unresectable. Helical computed tomography (CT) is very effective in detecting and staging adenocarcinoma, with a sensitivity of up to 90% for detection and an accuracy of 80-90% for staging, but it has limitations in detecting small cancers. Moreover, it is not very accurate for determining nonresectability because small liver metastases, peritoneal carcinomatosis, and subtle signs of vascular infiltration may be missed. Multidetector-row CT (MDCT) has brought substantial improvements with its inherent ability to visualize vascular involvement in three dimensions. MDCT has been found to be at least equivalent to contrast-enhanced magnetic resonance imaging (MRI) for detecting adenocarcinoma. MRI can be used as a problem-solving tool in equivocal CT: MRI may help rule out pitfalls, such as inflammatory pseudotumor, focal lipomatosis, abscess, or cystic tumors. Mangafodipir-enhanced MRI reveals a very high tumor-pancreas contrast, which helps in diagnosing small cancers. Endosonography is, if available, also a very accurate tool for detecting small cancers, with a sensitivity of up to 98%. It is the technique of choice for image-guided biopsy if a histologic diagnosis is required for further therapy.

Manganese-enhanced MRI of the optic visual pathway and optic nerve injury in adult rats

PURPOSE

To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visual projections.

MATERIALS AND METHODS

MRI was performed 24 hours after unilateral intravitreal injection of MnCl2 (150 nmol) into adult Fischer rats that were divided into four groups: 1) controls (N = 5), 2) dose-response (N = 10, 0.2-200 nmol), 3) time-response with repeated MRI during 24-168 hours post injection (N = 4), and 4) optic nerve crush (ONC) immediately preceding the MnCl2 injection (N = 7). Control and ONC animals were reinjected with MnCl2 20 days after the first injection, and MRI was performed 24 hours later.

RESULTS

In the control group, the optic projection was visualized from the retina to the superior colliculus, with indications of transsynaptic transport to the cortex. There was a semilogarithmic relationship between the Mn2+ dose and Mn2+ enhancement from 4 to 200 nmol, and the enhancement decayed gradually to 0 by 168 hours. No Mn2+-enhanced signal was detected distal to the ON crush site. In the control group, similar enhancement was obtained after the first and second MnCl2 injections, while in the ONC group the enhancement proximal to the crush site was reduced 20 days post lesion (20 dpl).

CONCLUSION

Mn2+-enhanced MRI is a viable method for temporospatial visualization of normal and injured ON in the adult rat. The observed reduction in the Mn2+ signal proximal to the ONC is probably a result of retrograde damage to the retinal ganglion cells, and not of Mn2+ toxicity.

Mangafodipir trisodium-enhanced MR imaging of pancreatic disease

Our study aimed to assess the diagnostic capabilities of mangafodipir trisodium-enhanced MRI for the evaluation of pancreatic disease. Sixty-three patients suspected of having pancreatic disease underwent MRI with a 1.5-T device. After the acquisition of axial and coronal T2-weighted sequences, the MR protocol included T1-weighted fat-suppressed breath-hold SPGR images obtained before and 30 min after the infusion of Mn-DPDP (Teslascan). The detection of a focal pancreatic lesion and its intensity were evaluated in consensus by two observers, who also attempted to characterize each lesion as benign or malignant. The reviewers were blinded to patient identification and all clinical, laboratory and previous imaging findings. MR imaging results were correlated with surgery (n=37), laparoscopy (n=1), biopsy (n=2) and imaging follow-up (n=22). Sixty-two subjects were effectively included in our analysis because one patient was lost to follow-up; final malignant and benign diagnoses were determined in 22 (35%) and 29 (47%) of the patients, respectively. The level of confidence in the diagnosis of the pancreatic lesion was significantly increased by the administration of Mn-DPDP as demonstrated by ROC analysis of unenhanced and post-contrast image sets (P=0.009). Overall, on the basis of observers' readings, MR assessment of pancreatic disease resulted in 57 correct diagnoses (accuracy, 92%) and five (8%) incorrect diagnoses. The sensitivity, specificity, positive predictive value and negative predictive value of the reviewers for the detection of pancreatic lesions and for the differentiation between benign and malignant masses were 91% (95% CI: 84 and 98%), 93% (95% CI: 86 and 99%), 87% (95% CI: 79 and 95%) and 95% (95% CI: 89 and 100%), respectively. Mn-DPDP-enhanced MRI is an effective diagnostic tool for evaluating pancreatic disease.

Diagnosis of pancreatic cancer

The ability to diagnose pancreatic carcinoma has been rapidly improving with the recent advances in diagnostic techniques such as contrast-enhanced Doppler ultrasound (US), helical computed tomography (CT), enhanced magnetic resonance imaging (MRI), and endoscopic US (EUS). Each technique has advantages and limitations, making the selection of the proper diagnostic technique, in terms of purpose and characteristics, especially important. Abdominal US is the modality often used first to identify a cause of abdominal pain or jaundice, while the accuracy of conventional US for diagnosing pancreatic tumors is only 50-70%. CT is the most widely used imaging examination for the detection and staging of pancreatic carcinoma. Pancreatic adenocarcinoma is generally depicted as a hypoattenuating area on contrast-enhanced CT. The reported sensitivity of helical CT in revealing pancreatic carcinoma is high, ranging between 89% and 97%. Multi-detector-row (MD) CT may offer an improvement in the early detection and accurate staging of pancreatic carcinoma. It should be taken into consideration that some pancreatic adenocarcinomas are depicted as isoattenuating and that pancreatitis accompanied by pancreatic adenocarcinoma might occasionally result in the overestimation of staging. T1-weighted spin-echo images with fat suppression and dynamic gradient-echo MR images enhanced with gadolinium have been reported to be superior to helical CT for detecting small lesions. However, chronic pancreatitis and pancreatic carcinoma are not distinguished on the basis of degree and time of enhancement on dynamic gadolinium-enhanced MRI. EUS is superior to spiral CT and MRI in the detection of small tumors, and can also localize lymph node metastases or vascular tumor infiltration with high sensitivity. EUS-guided fine-needle aspiration biopsy is a safe and highly accurate method for tissue diagnosis of patients with suspected pancreatic carcinoma. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been suggested as a promising modality for noninvasive differentiation between benign and malignant lesions. Previous studies reported the sensitivity and specificity of FDG-PET for detecting malignant pancreatic tumors as being 71-100% and 64-90%, respectively. FDG-PET does not replace, but is complementary to morphologic imaging, and therefore, in doubtful cases, the method must be combined with other imaging modalities.

Aspects du pancréas normal. Variantes et malformations

Major advances have occurred with regards to imaging of the pancreas. In spite of harmonic imaging, US remains limited. Multi-detector CT allows excellent evaluation of the pancreatic parenchyma with multiplanar ductal and vascular reformations. MRI provides excellent evaluation of the pancreatic parenchyma using fat suppressed T1W images and excellent evaluation of the biliary tract and pancreatic duct using T2W images. Senile pancreas is characterized by atrophy and ductal dilatation, sometimes microcystic. Fatty infiltration of the pancreas could be focal or diffuse. Pancreas divisum is characterized by the absence of fusion of the pancreatic ducts with several anatomic variants. Annular pancreas results from malrotation of the pancreatic buds. MRI is the best technique to diagnose these malformations.

Identification and staging of pancreatic tumours using computed tomography, endoscopic ultrasound and mangafodipir trisodium-enhanced magnetic resonance imaging

Pancreatic malignancy can be staged by a number of different investigations, either alone or in combination. The purpose of the present study was to compare the use of endoscopic ultrasound, CT and mangafodipir trisodium-enhanced MRI for the staging of pancreatic malignancy, particularly with respect to determining resectability prior to surgery. Twenty-seven patients referred for the investigation of a suspected pancreatic malignancy were entered into the trial. All patients had contrast-enhanced CT, gadolinium and mangafodipir trisodium-enhanced MRI, and endoscopic ultrasound (EUS). Images were assessed for nodal staging, tumour staging and resectability for each investigation, and the results compared with findings at surgery. The results for the accuracy of MRI, CT and EUS, in detecting T4 disease versus T3 or lower was 78, 79 and 68%, respectively; nodal involvement was 56, 63 and 69%, respectively; and overall resectability (including the T stage, presence of involved nodes and metastases) was 83, 76 and 63%, respectively. There was no significant difference demonstrated between the three tests. The present study suggests that for patients referred for investigation and staging of pancreatic malignancy, EUS and MRI scanning convey little advantage over contrast-enhanced CT. Furthermore, although mangafodipir trisodium improved the conspicuity of pancreatic tumours, it has little influence on T staging.

State-of-the-art imaging of pancreatic neoplasms

Pancreatic imaging with multidetector CT allows multiphase acquisition of thin slices in a single breath-hold and is especially valuable in obtaining isotropic three-dimensional reformations that improves our ability to provide accurate pre-operative vascular mapping. Advanced MR technology allows faster imaging of pancreas, thus facilitating MR cholangiopancreatography. Use of tissue-specific MR contrast agents, endoscopic ultrasound and PET in pancreatic imaging has evolved considerably. This review article discusses the role of CT, MR, endoscopic ultrasound and PET imaging in pancreas.

Current status of imaging in pancreatic diseases

Recent technological developments in multidetector CT allow pancreatic imaging in a single breath-hold, which is especially valuable in obtaining isotropic three-dimensional reformations that improve our ability to provide accurate preoperative vascular mapping. Advanced MR technology allows faster imaging of pancreas, thus facilitating MR cholangiopancreatography. Use of tissue-specific MR contrast agents, endoscopic ultrasound, and positron emission tomography (PET) in pancreatic imaging has evolved considerably. This review article discusses the roles of CT, MR, endoscopic ultrasound, and PET imaging in the pancreas.

Diagnosis and staging of pancreatic cancer: comparison of mangafodipir trisodium-enhanced MR imaging and contrast-enhanced helical hydro-CT

OBJECTIVE

The purpose of this study was to compare mangafodipir trisodium-enhanced MR imaging performed with a phased array coil and contrast-enhanced single-detector helical CT for accuracy in the detection and local staging of pancreatic adenocarcinoma and in the differentiation between cancer and focal pancreatitis.

SUBJECTS AND METHODS

Forty-two patients with suspected pancreatic masses underwent contrast-enhanced helical CT and mangafodipir trisodium-enhanced MR imaging at 1.5 T. The images were assessed for the presence or absence of tumors; characterization of masses; and presence of vascular invasion, lymph node metastases, or liver metastases. Imaging findings were correlated with findings at laparotomy, laparoscopy, biopsy, or follow-up.

RESULTS

Focal masses were present in 36 patients (cancer, n = 26; focal pancreatitis, n = 7; other, n = 3). The sensitivity for lesion detection of MR imaging was 100% and of CT, 94%. Two small malignant lesions were missed on CT. For the diagnosis of tumor nonresectability, the sensitivity of MR imaging and CT was 90% and 80%, respectively. Liver metastases were missed on MR imaging in one of the eight patients and on CT in four. For differentiation between adenocarcinoma and nonadenocarcinoma, the sensitivity of MR imaging was 100% (positive predictive value, 90%; negative predictive value, 100%), and the sensitivity of CT was 92% (positive predictive value, 80%; negative predictive value, 67%). Receiver operating characteristic analysis revealed that the mean area under the curve for MR imaging was 0.920 and for CT, 0.832 (not significant).

CONCLUSION

Mangafodipir trisodium-enhanced MR imaging is as accurate as contrast-enhanced helical CT for the detection and staging of pancreatic cancer but offers improved detection of small pancreatic metastases and of liver metastases compared with CT.

Magnetic resonance imaging in patients with pancreatitis: evaluation of signal intensity and enhancement changes

PURPOSE

To evaluate the utility of unenhanced and enhanced T1-weighted fat-suppressed (T1-FS) magnetic resonance imaging (MRI) in detecting pancreatitis.

MATERIALS AND METHODS

1.5-T MRI was performed in 25 patients with acute and 23 patients with chronic pancreatitis and in 20 control subjects without known pancreatic disease. T1-FS spin-echo and contrast-enhanced arterial-predominant (DYN1) and portal-predominant (DYN2) fast multiplanar spoiled gradient-echo (FMPSPGR) sequences were evaluated. These three sets of images were evaluated both subjectively for decreased or heterogeneous signal intensity (rating scale, 0-3) and objectively (region of interest (ROI)) in the head, body, and tail of the pancreas, in each patient.

RESULTS

Good correlation between subjective assessment and objective data was demonstrated. The T1-FS sequence showed an abnormality with greater frequency (T1-FS > DYN1, 81/144 scores; T1-FS = DYN1, 63/144 scores; T1-FS < DYN1, 0/144 scores) and magnitude (average subjective score, 2.48 vs. 1.74; P < 0.0003) than that of the contrast-enhanced FMPSPGR (decreased or heterogeneous enhancement). The overall sensitivity and specificity of MRI was 92% and 50%, respectively. On the basis of signal intensity and enhancement, MRI was not able to differentiate acute from chronic pancreatitis.

CONCLUSION

MRI was highly sensitive for disease detection, particularly using the T1-FS sequence, but using the sequences described, was not able to differentiate acute from chronic pancreatitis.

Functioning acinar cell pancreatic carcinoma: diagnosis on mangafodipir trisodium (Mn-DPDP)-enhanced MRI

We describe the imaging findings of a functional pancreatic acinar cell carcinoma in a patient who presented with weight loss, hyperlipasemia, and multiple foci of subcutaneous fat necrosis. The tumor invaded the adjacent splenic and portal vein, causing isolated left-sided portal hypertension. At MRI, the tumor showed marked enhancement following administration of the hepatobiliary-specific contrast agent mangafodipir trisodium (Mn-DPDP), thereby demonstrating the functional nature of the tumor. Avid uptake of Mn-DPDP by a functioning pancreatic tumor has not been reported in the radiology literature.

A review of contrast media research in 1999-2000

Contrast media research published during the years 1999 and 2000 is reviewed in this article, in terms of relevance to developments within the field of diagnostic radiology. The primary focus is on publications from the journal Investigative Radiology, which publishes much of the clinical and laboratory research performed in this field. The journals Radiology and the American Journal of Roentgenology are dominant in the field of diagnostic radiology and together publish more than 10 times the number of articles as appear each year in Investigative Radiology. However, in 1999 for example, these two journals together published fewer articles than did Investigative Radiology alone that concerned basic (animal) research with contrast media. Thirty-six percent of the articles in Investigative Radiology in 1999 had a primary focus on contrast media and 18% on basic (animal) research with contrast media. To make this review more complete, articles from other major journals are cited and discussed, as needed, to provide supplemental information in the few areas not well covered by articles in Investigative Radiology. The safety of contrast media is always an important topic and research continues to be performed in this area, both to explore fundamental issues regarding iodinated contrast media and also to establish the overall safety profile of new magnetic resonance (MR) and ultrasound agents. In regard to preclinical investigations, most of the work performed in the last 2 years has been with MR and ultrasound. In MR, research efforts continue to be focused on the development of targeted agents. In ultrasound, research efforts are split between studies looking at new imaging methods and early studies of targeted agents. In regard to the clinical application of contrast media, the published literature continues to be dominated by MR. Investigations include the study of disease in clinical trials and in animal models. A large number of studies continue to be published in regard to new techniques and applications within the field of contrast-enhanced magnetic resonance angiography. This field represents the single, largest new clinical application of contrast media in MR to emerge in the last decade. New clinical research continues to be published regarding the use of contrast media in computed tomography (CT), ultrasound, and x-ray angiography. The introduction of spiral CT (together with the multidetector scanners) has led to greater utilization of this modality, as well as intravenous iodinated contrast media. The number of publications regarding clinical applications of intravenously injected ultrasound contrast agents remains low, with the high expectations in regard to growth (in terms of number of exams using contrast) of the last decade yet to be fulfilled.