half-Fourier Acquisition Single-shot Turbo Spin-echo Sequence Research Articles

HASTE MRI sequence findings correlate with loss of deep pain perception in dogs with thoracolumbar disc extrusion.

Thoracolumbar intervertebral disc extrusion (TL IVDE) is a common reason for the veterinary hospital admission. Various imaging factors including degree and length of compression have been tested for correlation with clinical severity, but no reliable correlation has been found. Half-Fourier acquisition single-shot turbo spin echo (HASTE) magnetic resonance imaging (MRI) sequences highlight the dorsal and ventral cerebrospinal fluid (CSF) columns and have been used to demonstrate spinal cord swelling in dogs with TL IVDE. This has been used as a predictor of progressive ascending-descending myelomalacia but has not been correlated with neurological grade. This study aims to investigate the correlation between the attenuation of CSF HASTE signal and clinical severity in dogs suffering from TL disc extrusions. Dogs less than 15kg who were non-ambulatory due to suspected TL IVDE were prospectively recruited for a study into conservative management. MRI studies were undertaken under sedation including HASTE sequences. The ratio of the length of CSF attenuation to the length of the L2 vertebra was calculated and correlated with clinical severity. Twenty dogs met the inclusion criteria. No statistically significant difference was demonstrated between the mean CSF attenuation and neurological grade (p= 0.17 but there was a significant difference in the mean CSF attenuation in those who retained deep pain perception and those who did not (p= 0.02). Time to loss of ambulation was also found to not be correlated with CSF attenuation (p= 0.95). In conclusion, the length of CSF attenuation of HASTE MRI sequences in dogs less than 15kg suffering from IVDEs may be correlated with a loss of deep pain perception.

Diagnostic accuracy of a fast MRI T2-sequence for the diagnosis of internal herniation after Roux-and-Y gastric bypass during pregnancy: A retrospective single center study

PurposeThe objective of this retrospective study was to evaluate the diagnostic accuracy of a fast sequence Magnetic Resonance Imaging (MRI) sequence, T2- half-Fourier acquisition single-shot turbo spin echo (HASTE) for the diagnosis of internal herniation (IH) in pregnant patients with a history of Roux-en-Y gastric bypass (RYGB). MethodsAbdominal MRI studies, performed for the clinical suspicion of IH of pregnant patients with a history of RYGB, were analyzed by two abdominal radiologists. Thirty-one cases were included and for each case both readers independently evaluated the T2 HASTE sequence in different planes (axial, coronal and sagittal) to determine the presence or absence of IH. Diagnostic performance of T2 HASTE MRI was evaluated by calculating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy compared to the clinical diagnosis of IH as the gold standard. IH was diagnosed as the presence of herniated bowel through the mesenteric defect at the time of surgical exploration. IH was deemed absent if the surgical exploration showed no herniated bowel or if patients had no subsequent clinical symptoms of IH after 90 days of clinical follow-up. ResultsThe results in this study, with 16 patients with IH and 15 patients without IH, portray a high accuracy for the detection of IH, ranging from 87.9% to 90.3%. This fast T2 sequence shows a high NPV (86.7% - 100.0% 87.7), sensitivity (88.9% - 100.0%) and specificity (80.0% - 86.7%). This study also portrayed a substantial interobserver agreement (0.741) for the evaluation of IH. ConclusionT2 HASTE MRI shows an excellent sensitivity and NPV for the detection of IH in pregnant patients. The fast acquisition time makes this sequence useful in the emergency setting, and it can be used for the diagnosis or exclusion of IH in pregnant patients.

Impact of rescanning and repositioning on radiomic features employing a multi-object phantom in magnetic resonance imaging

Our purpose was to analyze the robustness and reproducibility of magnetic resonance imaging (MRI) radiomic features. We constructed a multi-object fruit phantom to perform MRI acquisition as scan-rescan using a 3 Tesla MRI scanner. We applied T2-weighted (T2w) half-Fourier acquisition single-shot turbo spin-echo (HASTE), T2w turbo spin-echo (TSE), T2w fluid-attenuated inversion recovery (FLAIR), T2 map and T1-weighted (T1w) TSE. Images were resampled to isotropic voxels. Fruits were segmented. The workflow was repeated by a second reader and the first reader after a pause of one month. We applied PyRadiomics to extract 107 radiomic features per fruit and sequence from seven feature classes. We calculated concordance correlation coefficients (CCC) and dynamic range (DR) to obtain measurements of feature robustness. Intraclass correlation coefficient (ICC) was calculated to assess intra- and inter-observer reproducibility. We calculated Gini scores to test the pairwise discriminative power specific for the features and MRI sequences. We depict Bland Altmann plots of features with top discriminative power (Mann–Whitney U test). Shape features were the most robust feature class. T2 map was the most robust imaging technique (robust features (rf), n = 84). HASTE sequence led to the least amount of rf (n = 20). Intra-observer ICC was excellent (≥ 0.75) for nearly all features (max–min; 99.1–97.2%). Deterioration of ICC values was seen in the inter-observer analyses (max–min; 88.7–81.1%). Complete robustness across all sequences was found for 8 features. Shape features and T2 map yielded the highest pairwise discriminative performance. Radiomics validity depends on the MRI sequence and feature class. T2 map seems to be the most promising imaging technique with the highest feature robustness, high intra-/inter-observer reproducibility and most promising discriminative power.

Utility of Various Ultrafast Magnetic Resonance Sequences in the Detection of Fetal Intracranial Hemorrhage.

Objective:The aim of this study is to compare the images obtained from standard ultrafast magnetic resonance (MR) imaging sequences with gradient (GRE) sequence images in identifying fetal intracranial hemorrhage (ICH).Materials and Methods:MR images of fetal brains with ICH done between October 2012 and September 2015 were reviewed. The images obtained from four ultrafast MR sequences– Turbo Fast Low Angle Shot (Turbo FLASH) T1-weighted images, Half Fourier Acquisition single-shot turbo spin echo (HASTE) T2-weighted images, b0 images of diffusion-weighted imaging (DWI) and b800 images of DWI were compared with images obtained from GRE sequence in depicting fetal ICH.Results:Out of the 212 fetuses during the study period, 15 fetuses had ICH. In the 15 fetuses with ICH as detected on GRE, Grade1 germinal matrix hemorrhage was seen in 5 fetuses, Grade 2 in 4 fetuses, Grade 3 in 3 fetuses, and Grade 4 in two fetuses. Subdural hemorrhage was seen in 1 fetus. In comparison to GRE sequence, b0 of DWI sequence was almost equal in the depiction of ICH. T2 HASTE sequence also delineated hemorrhage, although not as effectively as GRE and b0 images of images DWI. T1 Turbo FLASH and b800 images of DWI were less reliable in the depiction of fetal ICH but were useful in predicting the stage of hemorrhage.Conclusion:As compared to GRE sequence, b0 images of DWI followed by HASTE are the two preferred ultrafast sequences in the diagnosis of fetal ICH.

Clinical application of Half Fourier Acquisition Single Shot Turbo Spin Echo (HASTE) imaging accelerated by simultaneous multi-slice acquisition

PurposeAs a single-shot sequence with a long train of refocusing pulses, Half-Fourier Acquisition Single-Shot Turbo-Spin-Echo (HASTE) suffers from high power deposition limiting use at high resolutions and high field strengths, particularly if combined with acceleration techniques such as simultaneous multi-slice (SMS) imaging. Using a combination of multiband (MB)-excitation and PINS-refocusing pulses will effectively accelerate the acquisition time while staying within the SAR limitations. In particular, uncooperative and young patients will profit from the speed of the MB-PINS HASTE sequence, as clinical diagnosis can be possible without sedation.Materials and MethodsMB-excitation and PINS-refocusing pulses were incorporated into a HASTE-sequence with blipped CAIPIRINHA and TRAPS including an internal FLASH reference scan for online reconstruction. Whole brain MB-PINS HASTE data were acquired on a Siemens 3T-Prisma system from 10 individuals and compared to a clinical HASTE protocol.ResultsThe proposed MB-PINS HASTE protocol accelerates the acquisition by about a factor 2 compared to the clinical HASTE. The diagnostic image quality proved to be comparable for both sequences for the evaluation of the overall aspect of the brain, the detection of white matter changes and areas of tissue loss, and for the evaluation of the CSF spaces although artifacts were more frequently encountered with MB-PINS HASTE.ConclusionsMB-PINS HASTE enables acquisition of slice accelerated highly T2-weighted images and provides good diagnostic image quality while reducing acquisition time.

MRI of cystic fibrosis lung manifestations: sequence evaluation and clinical outcome analysis

To evaluate different magnetic resonance imaging (MRI) sequences for diagnosis of pulmonary manifestations of cystic fibrosis (CF) in comparison to chest computed tomography (CT), including an extended outcome analysis. Twenty-eight patients with CF (15 male, 13 female, mean age 30.5±9.4 years) underwent CT and MRI of the lung. MRI (1.5 T) included different T2- and T1-weighted sequences: breath-hold HASTE (half Fourier acquisition single shot turbo spin echo) and VIBE (volumetric interpolated breath-hold examination, before and after contrast medium administration) sequences and respiratory-triggered PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) sequences with and without fat signal suppression, and perfusion imaging. CT and MRI images were evaluated by the modified Helbich and the Eichinger scoring systems. The clinical follow-up analysis assessed pulmonary exacerbations within 24 months. The highest concordance to CT was achieved for the PROPELLER sequences without fat signal suppression (concordance correlation coefficient CCC of the overall modified Helbich score 0.93 and of the overall Eichinger score 0.93). The other sequences had the following concordance: PROPELLER with fat signal suppression (CCCs 0.91 and 0.92), HASTE (CCCs 0.87 and 0.89), VIBE (CCCs 0.84 and 0.85) sequences. In the outcome analysis, the combined MRI analysis of all five sequences and a specific MRI protocol (PROPELLER without fast signal suppression, VIBE sequences, perfusion imaging) reached similar correlations to the number of pulmonary exacerbations as the CT examinations. An optimum lung MRI protocol in patients with CF consists of PROPELLER sequences without fat signal suppression, VIBE sequences, and lung perfusion analysis to enable high diagnostic efficacy and outcome prediction.

USEFULNESS OF A HALF‐FOURIER ACQUISITION SINGLE‐SHOT TURBO SPIN‐ECHO PULSE SEQUENCE IN IDENTIFYING ARACHNOID DIVERTICULA IN DOGS

Single-shot turbo spin-echo sequences are heavily T2-weighted sequences that are exceptionally well suited to evaluate the subarachnoid space. In the T2-weighted fast spin-echo sequences that are used routinely in spinal magnetic resonance (MR) imaging, the subarachnoid space is not well differentiated from the surrounding epidural fat, which could lead to decreased detection of lesions of the subarachnoid space such as arachnoid diverticula. Our purpose was to determine the added value of a single-shot turbo spin-echo sequence in identifying cystic lesions of the subarachnoid space in dogs. MR images of six dogs with a confirmed arachnoid diverticulum and 24 dogs with other spinal disease were included. Six observers were asked to interpret only T2-weighted images initially, and in a second session, T2-weighted and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. The MR images were anonymized, and no signalment, history, or clinical information was provided. Without the HASTE sequences, 25% of arachnoid diverticula were identified. Adding the HASTE sequence increased the diagnosis of arachnoid diverticulum to 52.8%. The resulting difference, after adding the HASTE sequence, of 27.8% was statistically significant (P = 0.002). No false-positive diagnoses of arachnoid diverticulum were made with either sequence. Although sensitivity in this study was likely artificially low, the significantly increased detection rate of arachnoid diverticula when using HASTE imaging indicates that this sequence is a valuable addition to MR imaging protocols for the canine spine.

AGREEMENT BETWEEN T2 AND HASTE SEQUENCES IN THE EVALUATION OF THORACOLUMBAR INTERVERTEBRAL DISC DISEASE IN DOGS

The purpose of this study was to compare half-Fourier-acquisition single-shot turbo spin-echo (HASTE) and T2-weighted (T2-W) sequences in dogs with thoracolumbar disc extrusion. MRI studies in 60 dogs (767 individual intervertebral disc spaces) were evaluated. Agreement between T2-W and HASTE sequences was assessed for two criteria: presence of an extradural lesion and treatment recommendation. There was moderate agreement between T2-W and HASTE sequences as to presence of an extradural lesion (kappa = 0.575). HASTE was in agreement in 96.1% of the sites where no extradural lesion was identified on T2-W images, but only in 58.1% of the sites where extradural lesions were identified on T2-W images. There was also moderate agreement between T2-W and HASTE sequences as to treatment recommendations (kappa = 0.476). HASTE was in agreement in 98.4% of the sites where a lesion was considered nonsurgical on T2 but only 82.1% of sites a lesion was considered surgical on T2. In 1.0% of sites considered not surgical and in 9.8% of sites considered equivocal based on T2-W images, a surgical lesion was identified on HASTE. Acquisition of a HASTE sequence in addition to conventional sequences may be beneficial in determining the severity of spinal cord compression in some cases when evaluating the canine spine.

Diffusion-weighted imaging in the prostate: an apparent diffusion coefficient comparison of half-Fourier acquisition single-shot turbo spin-echo and echo planar imaging

Prostate cancer detection using diffusion-weighted imaging is highly affected by the accuracy of the apparent diffusion coefficient (ADC) values in an image. Echo planar imaging (EPI) is a fast sequence commonly used for diffusion imaging but has inherent magnetic susceptibility and chemical shift artefacts associated. A diffusion sequence that is less affected by these artefacts is therefore advantageous. The half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence was chosen. The diffusion sequences were compared in image quality, repeatability of the ADC value and the effect on the ADC value with varied b values. Eight volunteers underwent three scans of each sequence, on a 1.5-T Siemens system, using b values of 0, 150, 300, 450, 600, 750, 900 and 1000 s/mm 2. ADC maps were created to address the reproducibility of the ADC value when using two b values compared to eight b values. The ADC value using all b values with the HASTE sequence gave the best performance in all tested categories. Both sequences gave significantly different ADC mean values for two b values compared to when using eight b values ( P<.05) suggesting larger error is present when using two b values. HASTE was shown to be an improvement over EPI in terms of repeatability, signal variation within a region of interest and standard deviation over the volunteer set. The improved accuracy of the ADC value in the HASTE sequence makes it potentially a more sensitive tumor detection technique.

Examining the Relationship between the Lung-to-Head Ratio Measured on Ultrasound and Lung Volumetry by Magnetic Resonance in Fetuses with Isolated Congenital Diaphragmatic Hernia

Purpose: In fetuses with isolated congenital diaphragmatic hernia (CDH), lung development can be measured by the lung-to-head ratio (LHR) using ultrasound as well as by lung volumetry determined by fetal magnetic resonance imaging (MRI). We aimed to investigate their relationship as well as to analyze the factors that may have an impact on it. Material and Methods: In 153 consecutive fetuses with isolated CDH, both the LHR and total fetal lung volume (TFLV) were measured. The observed LHR was calculated by dividing the lung area by the head circumference. On MRI, planimetric measurements of ipsilateral, contralateral and TFLV were performed on T₂-HASTE (half-Fourier acquisition single-shot turbo spin echo) sequences in transverse as well as coronal or sagittal planes. All values were expressed as a ratio of what was observed over what is expected in a gestational age-matched normal fetus. Secondary analyses were performed for right- versus left-sided hernia and for measurements made prior to 25 weeks’ gestation. A multivariate linear regression approach was used to determine the influence of the independent variables such as observed/expected (O/E) LHR, gestational age, liver position and CDH side on the dependent variables O/E TFLV and O/E contralateral FLV, and to determine the optimal formulas for calculation of the O/E TFLV as well as contralateral FLV. Results: In total, 200 pairs of measurements were obtained between 20 and 37 weeks’ gestation (median 26+6). There was a significant association between the O/E contralateral FLV and O/E LHR (R² = 0.44; p < 0.001) as well as between the O/E TFLV and the O/E LHR (R² = 0.37; p < 0.001). After adding the independent variables that were first shown to be significant on univariate analysis, the multiple regression analysis demonstrated that gestational age (p = 0.017) and side of the defect (p < 0.001) were predictive of O/E LHR (p < 0.001) and strongly improved the estimation of O/E TFLV (R² = 0.43 instead of 0.37 when using O/E LHR only). In terms of estimating O/E contralateral FLV, only the O/E LHR was a significant (p < 0.001) independent predictor (R² = 0.44). These correlations also applied when considering only left-sided CDH cases. For measurements done prior to the third trimester, the O/E LHR (p = 0.034), gestational age (p = 0.035) as well as liver herniation (p = 0.029) were significantly correlated to the O/E TFLV (R² = 0.33). In terms of predicting the O/E contralateral FLV (R² = 0.25), only O/E LHR (p = 0.008) and gestational age (p = 0.037) were useful predictors. Conclusion: Measurement of the O/E LHR on ultrasound allows a good estimation of the O/E contralateral FLV as well as TFLV as measured by MRI. Whereas the additional parameters such as gestational age, liver position and side of the defect did not improve the estimation of the contralateral FLV, they did so for estimating the TFLV.

Magnetic resonance sialography using CISS and HASTE sequences in inflammatory salivary gland diseases: Comparison with digital sialography

Inflammatory conditions are the most common pathology affecting the salivary glands. Magnetic resonance (MR) sialography has emerged as an alternative to conventional sialography for evaluation of inflammatory salivary gland diseases. To prospectively evaluate the role and diagnostic accuracy of MR sialography in the diagnosis of inflammatory salivary gland disease. Thirty-seven glands in 28 patients (19 males and nine females; mean age 31 years, range 3-65 years) presenting with inflammatory salivary gland disorders underwent MR sialography. Conventional sialography was used as the gold standard and was performed in 26 patients (34 glands). Thus, comparative evaluation was done in 26 patients (34 glands). Axial T1-weighted (T1W) and fat-suppressed T2W sequences, a constructive interference in steady state (CISS) sequence in the axial plane with maximum intensity projection (MIP)/multiplanar reformation (MPR) done in the axial and sagittal oblique planes, and a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in the sagittal oblique direction were performed. Main salivary gland duct was visualized in 32 glands (94.1%) with MR sialography, and in all 34 (100%) glands with conventional sialography. Calculus and strictures were well demonstrated by MR sialography. MR sialography was superior for demonstration of the ductal system proximal to calculus/strictures. Sensitivity and specificity for diagnosis of specific pathology were 87% and 100% with CISS sequence and 90% and 75% with HASTE sequence, respectively. On using a combination of CISS and HASTE sequences, the sensitivity, specificity, and positive and negative predictive values in the diagnosis of specific pathology were 93%, 100%, 100%, and 64%, respectively. MR sialography using CISS and HASTE sequences is a promising technique and has the potential to replace conventional sialography in patients with inflammatory salivary gland disorders.

Fast magnetic resonance imaging evaluating of pulmonary progressive massive fibrosis with vibe and HASTE sequences: comparison with computed tomography imaging

The aim of this prospective study was to evaluate the diagnostic utility of volumetric interpolated breath-hold examination (VIBE) and half-Fourier-acquisition single-shot turbo spin-echo (HASTE) fast magnetic resonance imaging (MRI) sequences in the evaluation of pulmonary progressive massive fibrosis (PMF) in comparison with computed tomography (CT) imaging. If fast MRI is proven to be diagnostically significant, this modality can be used for diagnosis and follow-up studies of PMF patients. Twenty-two PMF lesions from 20 coal workers were evaluated. After CT imaging, patients underwent pre-contrast VIBE, contrast-enhanced VIBE, and HASTE MRI studies for detection and evaluation of the PMF lesions. Measurements of the three groups were evaluated with intra-class coefficients. Correlation levels between sizes, image quality, and artifact were evaluated with linear Pearson correlation analysis. There was almost perfect agreement among radiologists for lesion detection with kappa analysis. There was significant agreement between three MRI study groups and gold standard CT images. We found the best agreement values with contrast- enhanced VIBE images for lesion detection and image quality in comparison with CT imaging. Presence of artifact was also lowest with this protocol. With fast MRI sequences in pulmonary imaging, image quality has significantly improved being very close to that of CT studies. In this study, contrast-enhanced VIBE protocol provided the best depiction of PMF lesions. This protocol may be an alternative choice for CT, avoiding the use of iodinated contrast material and minimizing exposure to ionizing radiation for follow-up studies.

Application of magnetic resonance imaging to measure fasting and postprandial volumes in humans

Our aims were to measure the gastric volume response in excess of ingested meal volume (i.e. gastric accommodation), contribution of swallowed air to this excess, day-to-day variability of gastric volumes measured by MRI and their relationship to volumes measured by single-photon-emission computed tomography (SPECT). In 20 healthy volunteers, fasting and postprandial gastric volumes were measured after technetium(99m)-pertechnetate labeling of the gastric mucosa by SPECT and separately by MRI, using 3D gradient echo and 2D half-Fourier acquisition single-shot turbo spin echo (HASTE) sequences. Ten of these subjects had a second MRI exam to assess intra-individual variation. Thereafter, another 10 subjects had two MRI studies during which they ingested the nutrient in 30 or 150 mL aliquots. During MRI, the postprandial gastric volume change exceeded the ingested meal volume by 106 +/- 12 mL (Mean +/- SEM). The HASTE and gradient echo sequences distinguished air from fluid under fasting and postprandial conditions respectively. This postprandial excess mainly comprised air (61 +/- 5 mL), which was not significantly different when ingested as 30 or 150 mL aliquots. Fasting and postprandial gastric volumes measured by MRI were generally reproducible within subjects. During SPECT, postprandial volumes increased by 158 +/- 18 mL; gastric volumes measured by SPECT were higher than MRI. MRI measures gastric volumes with acceptable performance characteristics; the postprandial excess primarily consists of air, which is not affected by the mode of ingestion. Gastric volumes are technique specific and differ between MRI and SPECT.

Magnetic resonance cholangiopancreatography in the diagnosis of primary sclerosing cholangitis

Magnetic resonance cholangiopancreatography (MRCP) is a less-invasive alternative to endoscopic retrograde cholangiopancreatography (ERCP) for the diagnosis of primary sclerosing cholangitis (PSC). This study evaluated the diagnostic accuracy of MRCP in PSC compared with ERCP, and assessed the diagnostic accuracy of different T2w sequences. 95 patients (69 PSC, 26 controls) were evaluated using both ERCP and MRCP. Exclusion criteria included secondary sclerosing cholangitis and contraindications to MRCP. The diagnosis of PSC was confirmed in 69 patients based on ERCP as the reference gold standard. MRCP was performed using a 1.5 Tesla MR unit, using breath hold, coronal and transverse half-Fourier acquisition single-shot turbo spin-echo (HASTE), coronal-oblique, fat-suppressed half-Fourier rapid acquisition with relaxation enhancement (RARE), and coronal-oblique, fat-suppressed, multisection, thin-section HASTE (TS-HASTE) sequences. The MRCP morphological criteria of PSC were evaluated and compared with ERCP. The sensitivity, specificity, and diagnostic accuracy were 86%, 77%, and 83%, respectively, using the MRCP-RARE sequence, and increased further to 93%, 77%, and 88%, respectively, by the inclusion of follow-up MRCP in 52 patients, performed at 6-12-month intervals. HASTE and TS-HASTE sequences showed significantly lower diagnostic accuracy but provided additional morphologic information. MRCP can diagnose PSC but has difficulties in early PSC and in cirrhosis, and in the differentiation of cholangiocarcinoma, Caroli's disease, and secondary sclerosing cholangitis. A positive MRCP would negate some diagnostic ERCP studies but a negative MRCP would not obviate the need for ERCP.

“MR Cholangiopancreatography Using HASTE (Half-Fourier Acquisition Single-Shot Turbo Spin-Echo) Sequences”—A Commentary

Each month the American Journal of Roentgenology will republish online one of the 100 most-cited articles from its first century. A corresponding commentary in the print journal by a contemporary radiologist will provide a current perspective. For a full list of these articles, see page 3 of the January 2006 issue of the AJR or go to www.ajronline.org. Centennial article series Guest Editor: Liem T. Bui-Mansfield, ARRS Figley Fellow 2004.

Abdominal Magnetic Resonance Imaging at 3.0 T: What Is the Ultimate Gain in Signal-to-Noise Ratio?

The purpose of this study was to calculate the gain in signal-to-noise ratio (SNR) of four human abdominal tissues at 3.0 Tesla (T) compared with standard 1.5 T and to validate this calculation in vivo. The expected gain in SNR at 3.0 T in the liver, pancreas, spleen, and kidney compared with standard 1.5 T was approximated theoretically for a T2-weighted HASTE (half-Fourier acquisition single-shot turbo spin-echo) and a T1-weighted gradient-echo in- and opposed-phase sequence. Fifteen healthy male subjects underwent abdominal MR imaging using a 1.5 T and 3.0 T scanner. Coronal T2-weighted HASTE images and axial T1-weighted gradient-echo in- and opposed-phase images were acquired using the sequence parameters optimized by the vendor. Except for opposed-phased imaging of pancreatic tissue, in vivo adjusted SNR values of all abdominal tissues were significantly higher at 3.0 T for all sequences (P < .05). The highest overall gain in SNR was achieved with the HASTE sequence ranging from 3.8-fold for renal imaging to 7.4-fold for hepatic imaging. The theoretical calculation of SNR gain was in good agreement with the experimentally measured gain in SNR for the HASTE and the in-phase sequence. High-field abdominal MR imaging at 3.0 T offers significantly higher SNR compared with standard 1.5 T MR imaging.

Differentiation between hepatic cyst and hemangioma: Additive value of breath‐hold, multisection fluid‐attenuated inversion‐recovery magnetic resonance imaging using half‐Fourier acquisition single‐shot turbo‐spin‐echo sequence

To evaluate the additive value of breath-hold, multisection fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI) using half-Fourier acquisition single-shot turbo-spin-echo (HASTE) sequence as supplements to moderately and heavily T2-weighted fast-spin-echo (FSE) sequences in differentiating hepatic cyst from hemangioma. A total of 183 lesions (127 hepatic cysts, 56 hepatic hemangiomas) in 117 patients were evaluated in this study. Three radiologists independently reviewed FLAIR MR images using a HASTE sequence and T2-weighted FSE MR images. Each radiologist used a five-point scale to rate his confidence in determination of hepatic cyst and hemangioma. All three reviewers were significantly better able to differentiate hepatic cyst from hepatic hemangioma with the combination of FLAIR imaging using HASTE and moderately and heavily T2-weighted FSE images (area under the receiver operating characteristic (ROC) curve, 0.99 for each reader) than with moderately and heavily T2-weighted FSE images alone (0.82-0.93; P < 0.05). FLAIR-HASTE imaging in addition to T2-weighted FSE sequences improved the diagnostic performance, including the sensitivity, specificity, accuracy, and confident diagnosis in the differentiation between hepatic hemangiomas and cysts. FLAIR-HASTE imaging is useful for distinguishing hepatic hemangioma from hepatic cyst without the use of contrast-enhanced MR images.

Magnetic resonance imaging with true fast imaging with steady‐state precession and half‐fourier acquisition single‐shot turbo spin‐echo sequences in cases of suspected placenta accreta

To present the magnetic resonance imaging (MRI) findings of placenta accreta in suspected cases of placenta accreta with true fast imaging with steady-state precession (True FISP) and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. Five patients underwent MRI with HASTE (n = 5) and/or True FISP (n = 4) sequences for suspected placenta accreta. Retrospective review of MRI was performed to define the location and extent of the implantation abnormality. The uteroplacental interface was visualized as three layers; inner low signal intensity layer, middle high signal intensity layer of myometrium, and outer low signal intensity layer of uterine serosa. Three cases were diagnosed with placenta accreta on MRI and focal non-visualization of the inner layer was demonstrated. The finding of focal non-visualization of the inner layer between the placenta and myometrium by MRI with True FISP and HASTE sequences was the diagnostic finding for placenta accreta.

MR imaging of the congenital hypertrophic pyloric stenosis using the HASTE sequence in a 2-month-old infant

Congenital hypertrophic pyloric stenosis (CHPS) is the most common cause of gastric outlet obstruction during the first 3 months of life. Different diagnostic tools have been used to define this entity, with ultrasonography (US) and a barium meal (UGI) used most commonly. We report MR appearance of CHPS on half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in a 2-month-old infant. We think that it combines the advantages of US and barium meal.

MR pyelography in the assessment of hydroureteronephrosis: single-shot thick-slab RARE versus multislice HASTE sequences.

We used magnetic resonance (MR) pyelography to compare the value of thick-slab single-shot rapid acquisition with relaxation enhancement (RARE) sequence with that of multislice half-Fourier acquisition single-shot turbo-spin-echo (HASTE) sequence in evaluating the full spectrum of morphologic features in a group of patients with hydronephrosis. MR pyelographic images, with the use of thick-slab RARE and multislice HASTE sequences in 90 patients, were evaluated for image quality, presence of hydronephrosis, and level and cause of obstruction. HASTE sequences provided images of better quality than did RARE sequences (p < 0.001). There was no statistically significant difference in demonstrating the presence of hydronephrosis (p = 0.5) and level of obstruction (p = 0.125). Sensitivity, specificity, and accuracy in diagnosing cause of obstruction were 61.7%, 62.5%, and 62%, respectively, for RARE sequences and 80%, 82.5%, and 81%, respectively, for HASTE sequences, with a statistically significant difference (all p < 0.05). Multislice HASTE sequence provides better diagnostic information than does thick-slab RARE sequence, particularly in evaluating the cause of obstruction.