Accuracy of Unenhanced MR Imaging in the Detection of Acute Appendicitis: Single-Institution Clinical Performance Review.

PURPOSE: To determine the accuracy of unenhanced magnetic resonance (MR) imaging in the detection of acute appendicitis in patients younger than 50 years who present to the emergency department with right lower quadrant (RLQ) pain. MATERIALS AND METHODS: The institutional review board approved this retrospective study of 403 patients from August 1, 2012, to July 30, 2014, and waived the informed consent requirement. A cross-department strategy was instituted to use MR imaging as the primary diagnostic modality in patients aged 3-49 years who presented to the emergency department with RLQ pain. All MR examinations were performed with a 1.5- or 3.0-T system. Images were acquired without breath holding by using multiplanar half-Fourier single-shot T2-weighted imaging without and with spectral adiabatic inversion recovery fat suppression without oral or intravenous contrast material. MR imaging room time was measured for each patient. Prospective image interpretations from clinical records were reviewed to document acute appendicitis or other causes of abdominal pain. Final clinical outcomes were determined by using (a) surgical results (n = 77), (b) telephone follow-up combined with review of the patient's medical records (n = 291), or (c) consensus expert panel assessment if no follow-up data were available (n = 35). Logistic regression analysis was performed to evaluate the sensitivity and specificity of MR imaging in the detection of acute appendicitis, and corresponding 95% confidence intervals were determined. RESULTS: Of the 403 patients, 67 had MR imaging findings that were positive for acute appendicitis, and 336 had negative findings. MR imaging had a sensitivity of 97.0% (65 of 67) and a specificity of 99.4% (334 of 336). The mean total room time was 14 minutes (range, 8-62 minutes). An alternate diagnosis was offered in 173 (51.5%) of 336 patients. CONCLUSION: MR imaging is a highly sensitive and specific test in the evaluation of patients younger than 50 years with acute RLQ pain that uses a rapid imaging protocol performed without intravenous or oral contrast material.

MR imaging of benign and malignant biliary conditions.

MR imaging is a noninvasive, radiation-free imaging method for evaluation of the biliary system. Continued advancements in MR imaging system hardware and sequence design, coupled with novel gadolinium chelate agents, allow for a detailed evaluation of the bile ducts and surrounding soft tissues. New hepatocyte-specific contrast agents may hold utility in the anatomic and functional evaluation of bile duct injury. MR imaging is also the imaging method of choice for bile duct tumor diagnosis, staging, and presurgical planning. Familiarity with the proper methodology of MR image acquisition and interpretation is critical for optimized diagnostic assessment.

MRI of diffuse liver disease: characteristics of acute and chronic diseases.

Diffuse liver disease, including chronic liver disease, affects tens of millions of people worldwide, and there is a growing need for diagnostic evaluation as treatments become more readily available, particularly for viral liver diseases. Magnetic resonance imaging (MRI) provides unique capabilities for noninvasive characterization of the liver tissue that rival or surpass the diagnostic utility of liver biopsies. There has been incremental improvement in the use of standardized MRI sequences, acquired before and after administration of a contrast agent, for the evaluation of diffuse liver disease and the study of the liver parenchyma and blood supply. More recent developments have led to methods for quantifying important liver metabolites, including lipids and iron, and liver fibrosis, the hallmark of chronic liver disease. Here, we review the MRI techniques and diagnostic features associated with acute and chronic liver disease.

MRI of hepatocellular carcinoma: an update of current practices.

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and liver transplantation is the optimal treatment for selected patients with HCC and chronic liver disease (CLD). Accurate selection of patients for transplantation is essential to maximize patient outcomes and ensure optimized allocation of donor organs. Magnetic resonance imaging (MRI) is a powerful tool for the detection, characterization, and staging of HCC. In patients with CLD, the MRI findings of an arterial-enhancing mass with subsequent washout and enhancing capsule on delayed interstitial phase images are diagnostic for HCC. Major organizations with oversight for organ donor distribution, such as The Organ Procurement and Transplantation Network (OPTN), accept an imaging diagnosis of HCC, no longer requiring tissue biopsy. In patients that are awaiting transplantation, or are not candidates for liver transplantation, localized therapies such as transarterial chemoembolization and radiofrequency ablation may be offered. MRI can be used to monitor treatment response. The purpose of this review article is to describe the role of imaging methods in the diagnosis, staging, and follow-up of HCC, with particular emphasis on established and evolving MRI techniques employing nonspecific gadolinium chelates, hepatobiliary contrast agents, and diffusion weighted imaging. We also briefly review the recently developed Liver Imaging Reporting and Data System (LI-RADS) formulating a standardized terminology and reporting structure for evaluation of lesions detected in patients with CLD.

MRI of diffuse liver disease: the common and uncommon etiologies.

Diffuse liver disease, including all causes of chronic liver disease, affects tens of millions of people worldwide. There is a growing need for diagnostic evaluation as treatments become more readily available, particularly for viral liver disease. Magnetic resonance imaging (MRI) provides unique capabilities for noninvasive characterization of liver tissue that rival or surpass the diagnostic utility of liver biopsies. There has been incremental improvement in the use of standardized MRI sequences, acquired before and after administration of contrast for the evaluation of diffuse liver disease, and this includes study of the liver parenchyma and blood supply. More recent developments have led to methods for quantifying important liver metabolites, including fat and iron, and liver fibrosis, which is the hallmark for chronic liver disease. In this study, we review the MRI techniques and diagnostic features associated with common and uncommon etiologies of diffuse liver diseases, including processes that lead to abnormal perfusion (e.g. Budd-Chiari syndrome, congestive hepatomegaly), deposition diseases (e.g. fatty liver, hemochromatosis, Wilson's disease), and abnormalities that are related to inflammation and fibrosis (e.g. primary sclerosing cholangitis, sarcoidosis).

FDG positron emission tomography/computed tomography scan may identify mantle cell lymphoma patients with unusually favorable outcome.

OBJECTIVE: Patients diagnosed with mantle cell lymphoma (MCL) have generally poor prognosis, but a minority have a longer survival. There are no markers to identify this group and no generally established prognostic index for MCL. Our objective was to assess the prognostic value of the staging FDG PET/computed tomography (CT) scan. METHODS: We retrospectively analyzed initial scans performed at three institutions on biopsy-proven, cyclin D (+) MCL patients. The association of the SUVmax of the 'hottest focus' with overall survival (OS) and failure-free survival (FFS) was evaluated. Receiver operating characteristic analysis of SUVmax versus survival was used to establish a cut-off point of 4.83. In addition, PET findings were compared with contrast-enhanced CT performed within 3 weeks in patients from one institution. RESULTS: Both the OS and FFS for patients with SUVmax greater than 5 were significantly decreased (P<0.01 and <0.001, respectively) as compared with the patients with SUV < or = 5. The 5-year OS for group with SUVmax < or = 5 was 87.7% and for SUVmax greater than 5 it was 34%. For SUVmax < or = 5, the median FFS was 45.3 months as compared with 10.6 months for SUVmax greater than 5. PET changed the stage as compared with CT alone in 45% of patients. CONCLUSION: Staging FDG PET/CT is superior to CT and may be used in the future for identification of a subset of MCL patients with a better outcome than otherwise expected.

Granulomatous disease: is it a nuisance or an asset during PET/computed tomography evaluation of lung cancers?

OBJECTIVES: To evaluate combined PET-computed tomography (CT) criteria for differentiating between granulomatous disease (GD) and malignancy (CA) in oncologic PET-CT studies. METHODS: Sixty-two patients who were referred for fluoro-2-deoxyglucose (FDG) PET-CT evaluation of pulmonary lesion(s) without a history of concurrent infection were studied. PET-CT was performed 1.5 h after intravenous administration of 555 MBq 18F-FDG in the fasting state with oral contrast. Combined PET-CT criteria including (i) calcifications (Ca2+) within lymph nodes, (ii) Ca2+ in lung nodules, (iii) liver and/or spleen Ca2+, (iv) locations of lung lesion(s), (v) hilar FDG uptake, (vi) comparison of lung versus maximum mediastinal FDG uptake, (vii) lymph node uptake not in the most probable lymphatic drainage pathway from a particular lung lesion, and (viii) extra pulmonary abnormal FDG uptake were each assigned a numerical score (0-3) with progressively higher score and sum of scores toward the increasing likelihood of GD. These patients either had pathological confirmation by biopsy/resection or were followed radiographically for a period of 2 years (CA=13; GD=49). Discriminant analysis was performed on all the above criteria with this gold standard. Simple t-test and box plot analysis were also performed on the summation of the scores (from 0 in CA to 13 in GD). RESULTS: When all eight criteria were entered into discriminant analysis, the combined PET-CT criteria classified correctly 71% of patients with a sensitivity of 65% and specificity of 92% for GD. The most significant discriminating criterion was FDG uptake in the lung lesion(s) less than maximum mediastinal uptake (P=0.01). The sum scores in GD and CA were significantly different (4.9+/-2.4 vs. 3.2+/-1.5, respectively, P=0.014). Box plots showed a clear separation at a cut-off value of around 3.5. CONCLUSION: Results show that the set of combined PET-CT criteria are highly specific for GD, which is not necessarily a nuisance during oncologic evaluation. Knowledge of these criteria may attribute some of the abnormal PET findings to GD, which is a useful asset for quick recognition and clinical interpretation.

Investigating the existence of quantum metabolic values in non-Hodgkin's lymphoma by 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography.

OBJECTIVES: To investigate the existence of quantum metabolic values in various subtypes of non-Hodgkin's lymphoma (NHL). METHODS: Fifty-eight patients with newly diagnosed NHL and positron emission tomography (PET) performed within three months of biopsy were included. The standardized uptake value (SUV) from PET over the area of biopsy and serum glucose [Glc] were recorded. The group glucose sensitivity(G) for indolent and aggressive NHL was obtained by linear regression with ln(SUV) = G x ln[Glc] + C, where C is a constant for the group. Finally, the individual's glucose sensitivity (g) was obtained by g = {ln(SUV)-C}/ln[Glc], along with their means in various subtypes of NHL. To further investigate the influence of extreme [Glc] conditions, the SUVs corrected by the individually calculated g at various glucose levels, [Glc'] using SUV' =SUV x {[Glc']/[Glc]}(g), were compared to the original SUVs for both indolent and aggressive NHL. RESULTS: The averaged g (=G) for aggressive was significant different from that for indolent NHL (-0.94 +/- 0.51 vs. +0.13 +/- 0.10, respectively, p < 0.00005). There were significant differences in SUV for [Glc] < 80 or >110 mg/dl for both types of NHL. Unlike overlap among SUVs between NHL subtypes, the g value clearly categorized them into two distinct groups with positive (near-zero) and negative g values (around -1) for the indolent and aggressive NHLs, respectively. CONCLUSIONS: Distinct quantum metabolic values of -1 and 0 were noted in NHL. Aggressive NHL has a more negative value (or higher glucose sensitivity) than that of indolent and, thus, is more susceptible to extreme glucose variation.