Improved fat water separation with water selective inversion pulse for inversion recovery imaging in cardiac MRI

Purpose:

To develop an improved chemical shift‐based water‐fat separation sequence using a water‐selective inversion pulse for inversion recovery 3D contrast‐enhanced cardiac magnetic resonance imaging (MRI).

Materials and Methods:

In inversion recovery sequences the fat signal is substantially reduced due to the application of a nonselective inversion pulse. Therefore, for simultaneous visualization of water, fat, and myocardial enhancement in inversion recovery‐based sequences such as late gadolinium enhancement imaging, two separate scans are used. To overcome this, the nonselective inversion pulse is replaced with a water‐selective inversion pulse. Imaging was performed in phantoms, nine healthy subjects, and nine patients with suspected arrhythmogenic right ventricular cardiomyopathy plus one patient for tumor/mass imaging. In patients, images with conventional turbo‐spin echo (TSE) with and without fat saturation were acquired prior to contrast injection for fat assessment. Subjective image scores (1 = poor, 4 = excellent) were used for image assessment.

Results:

Phantom experiments showed a fat signal‐to‐noise ratio (SNR) increase between 1.7 to 5.9 times for inversion times of 150 and 300 msec, respectively. The water‐selective inversion pulse retains the fat signal in contrast‐enhanced cardiac MR, allowing improved visualization of fat in the water‐fat separated images of healthy subjects with a score of 3.7 ± 0.6. Patient images acquired with the proposed sequence were scored higher when compared with a TSE sequence (3.5 ± 0.7 vs. 2.2 ± 0.5, P < 0.05).

Conclusion:

The water‐selective inversion pulse retains the fat signal in inversion recovery‐based contrast‐enhanced cardiac MR, allowing simultaneous visualization of water and fat. J. Magn. Reson. Imaging 2013;37:484–490. © 2012 Wiley Periodicals, Inc.     

Comparison of R2* correction methods for accurate fat quantification in fatty liver

Purpose:

To compare the performance of fat fraction quantification using single‐R₂* and dual‐R₂* correction methods in patients with fatty liver, using MR spectroscopy (MRS) as the reference standard.

Materials and Methods:

From a group of 97 patients, 32 patients with hepatic fat fraction greater than 5%, as measured by MRS, were identified. In these patients, chemical shift encoded fat‐water imaging was performed, covering the entire liver in a single breathhold. Fat fraction was measured from the imaging data by postprocessing using 6 different models: single‐ and dual‐R₂* correction, each performed with complex fitting, magnitude fitting, and mixed magnitude/complex fitting to compare the effects of phase error correction. Fat fraction measurements were compared with co‐registered spectroscopy measurements using linear regression.

Results:

Linear regression demonstrated higher agreement with MRS using single‐R₂* correction compared with dual‐R₂* correction. Among single‐R₂* models, all 3 fittings methods performed similarly well (slope = 1.0 ± 0.06, r² = 0.89–0.91).

Conclusion:

Single‐R₂* modeling is more accurate than dual‐R₂* modeling for hepatic fat quantification in patients, even in those with high hepatic fat concentrations. J. Magn. Reson. Imaging 2013;37:414–422. © 2012 Wiley Periodicals, Inc.     

Grade progression and regression in recurrent urothelial cancer

PURPOSE: Recurrent urothelial cancers are reported to have characteristics similar to those of the primary tumor, with 10% to 25% of low grade tumors recurring as high grade disease. We determined how often grade progression and regression occur and whether abnormalities in p53 protein expression in original tumors are preserved in recurrences. MATERIALS AND METHODS: Two groups of patients treated for recurrent stages Ta/T1 urothelial bladder cancers with at least 1 tumor-free examination between the index and recurrent tumors were reviewed. Group 1 included 115 patients in whom the first available tumor was compared with the last recurrence and group 2 included 42 in whom the initial tumor was compared with the first recurrence. Immunohistochemical analysis of p53 expression was performed on a subset of 34 tumor pairs. RESULTS: In group 1, 33 grade 3 tumors (45%) recurred as grade 1 or 2 tumors, while 9 of 82 grades 1 and 2 tumors (11%) recurred as grade 3 tumors. Five of 7 group 2 grade 3 tumors (71%) recurred as grade 1 or 2 disease, while 1 of 35 grades 1 and 2 tumors (3%) recurred as grade 3 disease. In the 34 pairs studied immunohistochemically 6 of 14 grade 3 tumors recurred at lower grades. Nuclear p53 over expression occurred in 21 index tumors (12 of 14 grade 3, 8 of 17 grade 2 and 1 of 3 grade 1) and in 9 recurrences (6 of 10 grade 3, 2 of 17 grade 2 and 1 of 7 grade 1). Only 7 of 21 p53 positive and 2 of 12 p53 negative index tumors were p53 positive on recurrence. CONCLUSIONS: While progression from low to high grade occurred in less than 15% of patients, grade regression was observed in almost 50%. The loss of p53 positivity in regressing tumors indicates that these recurrences are molecularly distinct from the corresponding initial tumor.     

Multiecho water‐fat separation and simultaneous R estimation with multifrequency fat spectrum modeling

Multiecho chemical shift–based water‐fat separation methods are seeing increasing clinical use due to their ability to estimate and correct for field inhomogeneities. Previous chemical shift‐based water‐fat separation methods used a relatively simple signal model that assumes both water and fat have a single resonant frequency. However, it is well known that fat has several spectral peaks. This inaccuracy in the signal model results in two undesired effects. First, water and fat are incompletely separated. Second, methods designed to estimate T in the presence of fat incorrectly estimate the T decay in tissues containing fat. In this work, a more accurate multifrequency model of fat is included in the iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) water‐fat separation and simultaneous T estimation techniques. The fat spectrum can be assumed to be constant in all subjects and measured a priori using MR spectroscopy. Alternatively, the fat spectrum can be estimated directly from the data using novel spectrum self‐calibration algorithms. The improvement in water‐fat separation and T estimation is demonstrated in a variety of in vivo applications, including knee, ankle, spine, breast, and abdominal scans. Magn Reson Med 60:1122–1134, 2008. © 2008 Wiley‐Liss, Inc.     

Prospective evaluation of candidate urine and cell markers in patients with interstitial cystitis enrolled in a randomized clinical trial of Bacillus Calmette Guerin (BCG)

We measured candidate urine biomarkers and bladder cell DNA cytometry in interstitial cystitis (IC) patients randomized to receive intravesical Bacillus Calmette Guerin (BCG) or placebo in a multicenter trial. Participants received 6 weekly instillations and were followed for 34 weeks. Urine was collected at baseline, prior to fourth treatment, and at study end. Antiproliferative factor (APF) activity was determined by 3H-thymidine incorporation assay; heparin-binding epidermal growth factor-like growth factor (HB-EGF) and epidermal growth factor-like growth factor (EGF) levels were determined by ELISA. Cellular DNA content was measured by image analysis to determine the mean hyperdiploid fraction (HDF) of the urine cell pellet. Associations between marker levels, and treatment or symptoms, were examined. Baseline APF positivity rate and mean levels of the other biomarkers were similar to previous smaller studies. During the week 34 follow-up, mean HDF decreased (P = 0.0003) and HB-EGF increased (P < 0.0001); both correlated weakly with decreased urgency. There was no difference in any biomarker between symptom responders and non-responders, but the percentage of responders was low and not significantly different for BCG versus placebo. APF positivity, decreased HB-EGF, increased EGF, and increased HDF were confirmed at baseline in IC patients. Changes in HDF and HB-EGF levels correlated weakly with changes in urgency, but the low BCG response rate prevented identification of additional associations between biomarker changes and treatment or symptoms.     

Outcome measures and their everyday use in chiropractic practice

Objectives:

To describe the extent to which chiropractors utilize standardized outcome and various clinical measures to systematically document patients’ baseline health status and responses to treatment, with particular consideration being given towards quantifiable outcome instruments.

Study design:

Cross-sectional mailed survey.

Participants:

Registered chiropractors in the province of Saskatchewan.

Methods:

A survey was mailed to all registrants of the Chiropractors’ Association of Saskatchewan. Respondents graded their frequency of using various standardized pencil-and-paper instruments and functional chiropractic, orthopaedic and neurological tests in the contexts of both the initial intake assessment (‘always,’ ‘commonly,’ ‘occasionally,’ or ‘never’) and the course of subsequent treatment (after ‘each visit,’ after ‘9–12 visits,’ ‘annually,’ when patient ‘not responding,’ on ‘dismissal/discharge,’ ‘never’ or for some ‘other’ reason). Data were tabulated for all item and response category combinations as frequencies and percentages using the total sample size as the denominator.

Results:

Of 164 registered chiropractors, 62 (38%) returned a completed questionnaire. A pain diagram was the most commonly used subjective outcome measure and was administered routinely (either “always” or “commonly”) by 75% of respondents, at either the initial consultation or during a subsequent visit. Numerical rating and visual analogue scales were less popular (routinely used by 59% and 42% respectively). The majority of respondents (80%) seldom (“occasionally” or “never”) used spine pain-specific disability indices such as the Low Back Revised Oswestry, Neck Disability Index or the Roland-Morris Questionnaire. As well, they did not use standardized psychosocial instruments such as the Beck Depression Index, or general health assessment measures such as the SF-36 or SF-12 questionnaire. Neurological testing was the most commonly used objective outcome measure. Most respondents (84% to 95%) indicated that they continually monitored neurological status through dermatomal, manual muscle strength and deep tendon reflex testing. Ranges of motion were routinely measured by 95% of respondents, usually visually (96%) rather than goniometrically or by some other specialized device (7%).

Conclusions:

Our findings suggest that the majority of chiropractors do not use psychosocial questionnaires or condition-specific disability indices to document baseline or subsequent changes in health status. Chiropractors are more likely to rely on medical history taking and pain drawings during an initial intake assessment, as well as neurological and visually estimated range of motion testing during both initial intake and subsequent treatment visits.     

Ulcer recurrence after in‐hospital treatment for recalcitrant venous leg ulceration

Background Leg ulceration caused by chronic venous disease occurs in 1% of the adult Western population. A majority of these patients is successfully treated in the outpatient setting. A minority of patients is hospitalized, most frequently because of the lack of healing tendency. The literature provides recurrence rates for ulcer disease, but lacks specific data on recurrence rates after in‐hospital treatment of recalcitrant venous leg ulcers. Objectives To investigate time to ulcer recurrence after in‐hospital treatment of venous leg ulceration. Methods A multicentre, retrospective cohort study of patients admitted for leg ulceration between 1996 and 2007 was conducted. Results Data could be collected for 107 of the patients. Of these, 27 had conservative treatment (bed rest, local wound care, pain management) and 48 patients underwent surgical ulcer treatment with (n = 19) or without (n = 29) initial vacuum‐assisted closure (VAC) treatment. The treatment method was ‘miscellaneous’ in the remaining 32 patients. Median admission time was 30 days, median percentage of closure at discharge was 95%, and median time to ulcer recurrence 60 days. The Mann–Whitney U‐test showed significant differences between the conservative group and the surgery group, the latter having a longer length of hospital stay (P < 0·0001) and a higher percentage of ulcer closure (P < 0·0001), but there was no difference in time to ulcer recurrence (P = 0·273). Comparable differences were demonstrated between the conservative group and the VAC plus surgery group. No significant differences could be demonstrated between the surgically treated patients and those treated by VAC and surgery. Conclusions Hospital stay is significantly shorter in cases of surgical treatment of recalcitrant venous leg ulcers. Most ulcers recur within 2 months after hospital discharge. Recurrence of venous leg ulcers after hospital admission is independent of the method of treatment and cause of ulceration.     

Molecular epidemiology of Plasmodium falciparum resistance to antimalarial drugs in Indonesia

The extent of gene polymorphisms associated with resistance to chloroquine and sulfadoxine-pyrimethamine was examined in field isolates of Plasmodium falciparum from Indonesia. Eight malaria-endemic areas, representing a broad region of the western and eastern Indonesian Archipelago were surveyed. Blood from 20-50 patients was collected at each site, DNA was isolated, and the sequences of four different genes (dihydrofolate reductase [dhfr], dihydropteroate synthase [dhps], P. falciparum multidrug resistance 1 [pfmdr1], and P. falciparum chloroquine resistance transporter [pfcrt]) were analyzed using polymerase chain reaction and restriction fragment length polymorphisms to detect polymorphisms previously shown to be associated with resistance. This analysis identified polymorphisms in dhfr at 108-Asn/Thr, 16-Val, and 59-Arg. Polymorphisms in dhps were found less frequently, either 437-Gly alone or paired with 540-Glu. The pfcrt 76-Thr polymorphism was fixed in all parasite populations and pfmdr1 86-Tyr polymorphisms in all populations except in the most eastern regions. The pfmdr1 1042-Asp polymorphism occurred less frequently. These findings indicate that polymorphisms in genes associated with drug resistance in P. falciparum are found across a broad region of Indonesia.