Cartilage Imaging: Techniques and Developments.

Cartilage degeneration is one of the most common chronic age-related joint disorders leading to pain and reduced joint motion. The increasing prevalence of osteoarthritis requires accurate cartilage imaging, both clinically and in research. Detailed cartilage imaging is also necessary for traumatic cartilage lesions and for pre- and postoperative assessment of cartilage repair procedures. Although still widely used, conventional radiography bears significant limitations because it assesses cartilage indirectly by joint space width. Magnetic resonance imaging (MRI) enables direct visualization of cartilage damage along with other concomitantly affected joint tissues. Several semiquantitative grading systems and volumetric analysis methods exist to assess cartilage damage and cartilage repair on MRI. Quantification of hyaline and fibrocartilage biochemical composition is possible with novel MRI methods such as T2- and T1ρ-mapping, delayed gadolinium-enhanced MRI of cartilage, glycosaminoglycan chemical exchange saturation transfer, and sodium imaging, along with quantitative computed tomography arthrography. These techniques provide promising quantitative imaging biomarkers that can detect early cartilage changes before morphological alterations occur.

T2* mapping and delayed gadolinium-enhanced magnetic resonance imaging in cartilage (dGEMRIC) of humeral articular cartilage--a histologically controlled study.

BACKGROUND: Cartilage biochemical imaging modalities that include the magnetic resonance imaging (MRI) techniques of T2* mapping (sensitive to water content and collagen fiber network) and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC, sensitive to the glycosaminoglycan content) can be effective instruments for early diagnosis and reliable follow-up of cartilage damage. The purpose of this study was to provide T2* mapping and dGEMRIC values in various histologic grades of cartilage degeneration in humeral articular cartilage. METHODS: A histologically controlled in vitro study was conducted that included human humeral head cartilage specimens with various histologic grades of cartilage degeneration. High-resolution, 3-dimensional (3D) T2* mapping and dGEMRIC were performed that enabled the correlation of MRI and histology data. Cartilage degeneration was graded according to the Mankin score, which evaluates surface morphology, cellularity, toluidine blue staining, and tidemark integrity. SPSS software was used for statistical analyses. RESULTS: Both MRI mapping values decreased significantly (P < .001) with increasing cartilage degeneration. Spearman rank analysis revealed a significant correlation (correlation coefficients ranging from -0.315 to 0.784; P < .001) between the various histologic parameters and the T2* and T1Gd mapping values. CONCLUSION: This study demonstrates the feasibility of 3D T2* and dGEMRIC to identify various histologic grades of cartilage damage of humeral articular cartilage. With regard to the advantages of these mapping techniques with high image resolution and the ability to accomplish a 3D biochemically sensitive imaging, we consider that these imaging techniques can make a positive contribution to the currently evolving science and practice of cartilage biochemical imaging.

Spectrum of T2* values in knee joint cartilage at 3 T: a cross-sectional analysis in asymptomatic young adult volunteers.

OBJECTIVE: To establish baseline T2* values in healthy knee joint cartilage at 3 T. MATERIALS AND METHODS: Thirty-four volunteers (mean age: 24.6 ± 2.7 years) with no history or clinical findings indicative of any knee joint disease were enrolled. The protocol included a double-echo steady-state (DESS) sequence for morphological cartilage evaluation and a gradient-echo multi-echo sequence for T2* assessment. Bulk and zonal T2* values were assessed in eight regions: posterior lateral femoral condyle; central lateral femoral condyle; trochlea; patella; lateral tibial plateau; posterior medial femoral condyle; central medial femoral condyle; and medial tibial plateau. Statistical evaluation comprised a two-tailed t test and a one-way analysis of variance to identify zonal and regional differences. RESULTS: T2* mapping revealed higher T2* values in the superficial zone in all regions (P values ≤ 0.001) except for the posterior medial femur condyle (P = 0.087), and substantial regional differences demonstrating superior values in trochlear cartilage, intermediate values in patellar and central femoral condylar cartilage, and low T2* values in posterior femoral condylar cartilage and tibial plateau cartilage. CONCLUSION: Substantial regional differences in T2* measures should be taken into consideration when conducting T2* mapping of knee joint cartilage.

Kidney transplant: functional assessment with diffusion-tensor MR imaging at 3T.

PURPOSE: To evaluate the feasibility of diffusion-tensor (DT) imaging at 3 T for functional assessment of transplanted kidneys. MATERIALS AND METHODS: This study was approved by the local ethics committee; written informed consent was obtained. Between August 2009 and October 2010, 40 renal transplant recipients were prospectively included in this study and examined with a clinical 3-T magnetic resonance (MR) imager. An echo-planar DT imaging sequence was performed in coronal orientation by using five b values (0, 200, 400, 600, 800 sec/mm(2)) and 20 diffusion directions. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were determined for the cortex and medulla of the transplanted kidney. Relationships between FA, ADC, and allograft function, determined by the estimated glomerular filtration rate (eGFR), were assessed by using Pearson correlation coefficient. ADC and FA were compared between patients with good or moderate allograft function (group A; eGFR > 30 mL/min/1.73 m(2)) and patients with impaired function (group B; eGFR ≤ 30 mL/min/1.73 m(2)) by using a student t test. P < .05 indicated a statistically significant difference. RESULTS: Mean FA of the renal medulla and cortex was significantly higher in group A (0.39 ± 0.06 and 0.17 ± 0.4) compared with group B (0.27 ± 0.05 and 0.14 ± 0.03) (P < .001 and P = .009, respectively). Mean ADCs of renal cortex and medulla were significantly higher in group A than in group B (P = .007 and P = .01, respectively). In group B, mean medullary FA was significantly lower in patients whose renal function did not recover (0.22 ± 0.02) compared with those with stable allograft function at 6 months (0.29 ± 0.05, P < .001). There was significant correlation between eGFR and medullary FA (r = 0.65, P < .001), cortical ADC (r = 0.43, P = .003), and medullary ADC (r = 0.35, P = .01). CONCLUSION: DT imaging is a promising noninvasive technique for functional assessment of renal allografts. FA values in the renal medulla exhibit a good correlation with renal function.

T2* mapping and delayed gadolinium-enhanced magnetic resonance imaging in cartilage (dGEMRIC) of glenohumeral cartilage in asymptomatic volunteers at 3 T.

OBJECTIVES: To establish baseline T2* and T1Gd values of glenohumeral cartilage at 3 T. METHODS: Forty asymptomatic volunteers (mean age: 24.8 ± 2.2 years) without shoulder abnormalities were included. The MRI protocol comprised a double-echo steady-state (DESS) sequence for morphological cartilage evaluation, a gradient-echo multiecho sequence for T2* assessment, and a gradient-echo dual-flip-angle sequence for T1Gd mapping. Statistical assessment involved a one-way analysis of variance (ANOVA) to identify the differences between various regions of the glenohumeral joint and intraclass correlation (ICC) analysis comparing repetitive T2* and T1Gd measures to assess intra- and interobserver reliability. RESULTS: Both techniques revealed significant differences between superior and inferior glenohumeral cartilage demonstrating higher T2* (26.2 ms vs. 23.2 ms, P value < 0.001) and T1Gd (750.1 ms vs. 720.2 ms, P value = 0.014) values in the superior regions. No trend was observed in the anterior-posterior measurement (P value range: 0.279-1.000). High intra- and interobserver agreement (ICC value range: 0.895-0.983) was noted for both T2* and T1Gd mapping. CONCLUSIONS: T2* and T1Gd mapping are reliable in the assessment of glenohumeral cartilage. The values from this study can be used for comparison to identify cartilage degeneration in patients suffering from shoulder joint abnormalities. KEY POINTS: • T2* mapping and dGEMRIC are sensitive to collagen degeneration and proteoglycan depletion. • This study aimed to establish baseline T2*/dGEMRIC values of glenohumeral cartilage. • Both techniques revealed significant differences between superior and inferior glenohumeral cartilage. • High intra-/interreader agreement was noted for both T2* mapping and dGEMRIC. • These baseline normal values should be useful when identifying potential degeneration.

Magnetic resonance imaging and histology of ovine hip joint cartilage in two age populations: a sheep model with assumed healthy cartilage.

OBJECTIVE: To compare morphologically normal appearing cartilage in two age groups with delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and correlate magnetic resonance imaging (MRI) findings with histology. MATERIALS AND METHODS: Twenty femoral head specimens collected from ten lambs (group I) and ten young adult sheep (group II) underwent dGEMRIC and histological assessment. A region of 2 cm(2) with morphologically normal-appearing cartilage was marked with a surgical suture for subsequent matching of MRI and histological sections. The MRI protocol included a three-dimensional (3D) double-echo steady-state sequence for morphological cartilage assessment, a B1 pre-scan with various flip angles for B1 field heterogeneity correction, and 3D volumetric interpolated breathhold examination for T1(Gd) mapping (dGEMRIC). Histological analysis was performed according to the Mankin scoring system. RESULTS: A total of 303 regions of interest (ROI; 101 MRI reformats matching 101 histological sections) was assessed. Twenty-six ROIs were excluded owing to morphologically apparent cartilage damage or insufficient MR image quality. Therefore, 277 ROIs were analyzed. Histological analyses revealed distinct degenerative changes in various cartilage samples of group II (young adult sheep). Corresponding T1(Gd) values were significantly lower in the group of sheep (mean T1(Gd) = 540.4 ms) compared with the group of lambs (mean T1(Gd) = 623.6 ms; p < 0.001). CONCLUSIONS: Although morphologically normal, distinct cartilage degeneration may be present in young adult sheep cartilage. dGEMRIC can reveal these changes and may be a tool for the assessment of early cartilage degeneration.

Quantitative assessment of bone defect healing by multidetector CT in a pig model.

OBJECTIVE: To evaluate multidetector CT volumetry in the assessment of bone defect healing in comparison to histopathological findings in an animal model. MATERIALS AND METHODS: In 16 mini-pigs, a circumscribed tibial bone defect was created. Multidetector CT (MDCT) of the tibia was performed on a 64-row scanner 42 days after the operation. The extent of bone healing was estimated quantitatively by MDCT volumetry using a commercially available software programme (syngo Volume, Siemens, Germany).The volume of the entire defect (including all pixels from -100 to 3,000 HU), the nonconsolidated areas (-100 to 500 HU), and areas of osseous consolidation (500 to 3,000 HU) were assessed and the extent of consolidation was calculated. Histomorphometry served as the reference standard. RESULTS: The extent of osseous consolidation in MDCT volumetry ranged from 19 to 92% (mean 65.4 ± 18.5%). There was a significant correlation between histologically visible newly formed bone and the extent of osseous consolidation on MDCT volumetry (r = 0.82, P < 0.0001). A significant negative correlation was detected between osseous consolidation on MDCT and histological areas of persisting defect (r = -0.9, P < 0.0001). CONCLUSION: MDCT volumetry is a promising tool for noninvasive monitoring of bone healing, showing excellent correlation with histomorphometry.

Nonenhanced ECG-gated time-resolved 4D steady-state free precession (SSFP) MR angiography (MRA) for assessment of cerebral collateral flow: comparison with digital subtraction angiography (DSA).

OBJECTIVES: To evaluate a nonenhanced time-resolved 4D SSFP MRA for dynamic visualization of intracranial collateral blood flow. METHODS: 22 patients (59.0 ± 11.8 years) with steno-occlusive disease of brain-supplying arteries were included in this study. 4D SSFP MRA of the intracranial arteries was acquired with 15 temporal phases and a temporal resolution of 115 ms using 1.5 T MR. Cerebral DSA served as the reference standard and was available in all patients. RESULTS: Nonenhanced 4D SSFP MRA allowed for detailed dynamic visualization of blood flow in the circle of Willis and its branches in 21 of 22 (95.5%) patients. Collateral flow was excluded with both 4D SSFP MRA and DSA in 4 patients. In 17 patients, DSA detected anterior collateral flow (n = 8), posterior collateral flow via the right (n = 8) and left (n = 7) posterior communicating artery as well as patent EC-IC bypasses (n = 8). 29 of 31 collateral flow pathways were visualized by 4D SSFP MRA. As compared to DSA, 4D SSFP MRA showed a high sensitivity (92.3%), specificity (100%), positive predictive value (100%) and negative predictive value (95.2%) for visualization of intracranial collateral flow. CONCLUSIONS: 4D SSFP MRA is a promising non-invasive imaging technique for dynamic visualization of intracranial collateral flow.

CT-guided biopsy of thoracic lesions with a novel wire-based needle guide device - initial experiences.

BACKGROUND: Biopsies guided by computed tomography (CT) play an important role in clinical practice. A short duration, minimal radiation dose and complication rate are of particular interest. Purpose To evaluate the potential of a novel self-manufactured wire-based needle guide device for CT-guided thoracic biopsies with respect to radiation dose, intervention time and complication rate. MATERIAL AND METHODS: Forty patients that underwent CT-guided biopsies of thoracic lesions were included in this study and assigned to two groups. Patients in group A (n = 20, mean age 69 ± 8.4 years) underwent biopsies with a novel wire-based needle guide device, while patients in group B (n = 20, mean age 68.4 ± 10.1 years) were biopsied without a needle guide device. The novel self-manufactured needle guide device consists of an iron/zinc wire modelled to a ring with a flexible arm and an eye at the end of the arm to stabilize the biopsy needle in the optimal position during intervention. Predefined parameters (radiation dose, number of acquired CT-slices, duration of intervention, complications) were compared between both groups. RESULTS: Mean radiation dose (CTDIvol 192 mGy versus 541 mGy; P ≤ 0.001) and the number of acquired slices during intervention (n = 49 ± 33 vs. n = 126 ± 78; P ≤ 0.001) were significantly lower in group A compared with group B. Intervention time in group A (13.1 min) was significantly lower than in group B (18.5 min, P < 0.01). A pneumothorax as peri-interventional complication was observed less frequent after device assisted biopsies (n = 4 vs. n = 8, n.s.). CONCLUSION: The novel wire-based needle guide device is a promising tool to facilitate CT-guided thoracic biopsies reducing radiation dose, intervention time, and related complications. Further studies are mandatory to confirm these initial results.

Periportal edema in trauma patients: correlation with trauma severity.

BACKGROUND: Periportal edema (PPE) can be seen in different clinical settings, including in patients following trauma. However, the underlying mechanisms and clinical significance in trauma patients still remain unclear. PURPOSE: To determine the incidence of PPE in CT scans of trauma patients and to correlate PPE with trauma severity and different patterns of injury. MATERIAL AND METHODS: We retrospectively analyzed contrast-enhanced spiral CT scans of 127 trauma patients that were referred to our Trauma Center Level I between January 2006 and June 2007. According to the Injury Severity Score (ISS), 70 patients with an ISS < 16 (minor trauma) were assigned to group 1 and 57 patients with an ISS ≥16 (major trauma) to group 2. RESULTS: The presence of PPE was significantly (p < 0.01) higher in group 2 (22 of 57 patients [38.6%]) than in group 1 (10 of 70 patients [14.3%]). In 29 patients PPE presented with a diffuse pattern and in three patients with a focal pattern, affecting only one liver lobe. In 14 patients PPE was found in absence of abdominal injuries. In addition, PPE was present in five patients with abdominal injuries but without liver injury. CONCLUSION: PPE is seen significantly more often on abdominal CT scans following major traumas (ISS ≥ 16), but is not necessarily associated with liver injury.

Metacarpophalangeal joints in rheumatoid arthritis: delayed gadolinium-enhanced MR imaging of cartilage--a feasibility study.

PURPOSE: To evaluate the feasibility of delayed gadolinium-enhanced magnetic resonance (MR) imaging of the cartilage of metacarpophalangeal (MCP) joints in patients with rheumatoid arthritis (RA) compared with that in control subjects. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Thirty-one MCP joints in 10 patients with RA (mean age, 59 years; range, 35-77 years) and six healthy volunteers (mean age, 51 years; range, 30-71 years) were examined with delayed gadolinium-enhanced MR imaging of cartilage. Sagittal images of the second and third MCP joints (hereafter, MCP II and MCP III) were acquired with a three-dimensional dual-flip-angle gradient-echo sequence at 3.0 T. B(1) field inhomogeneity-corrected T1 maps were calculated, and delayed gadolinium-enhanced MR imaging of cartilage values for phalangeal and metacarpal cartilage were determined. In addition, cartilage thickness was measured. A nonparametric Mann-Whitney U test was used to assess differences between groups. RESULTS: Phalangeal and metacarpal delayed gadolinium-enhanced MR imaging of cartilage values in patients with RA (MCP II: 388 msec ± 105 [standard deviation] and 342 msec ± 79, respectively; MCP III: 409 msec ± 96 and 371 msec ± 89, respectively) were significantly lower than in control subjects (MCP II: 598 msec ± 62 and 560 msec ± 51, respectively; MCP III: 586 msec ± 57 and 561 msec ± 80, respectively). Cartilage thickness of both joints was comparable in patients with RA (MCP II: 1.28 mm ± 0.50, MCP III: 1.17 mm ± 0.24) and control subjects (MCP II: 1.42 mm ± 0.33, MCP III: 1.18 mm ± 0.26). CONCLUSION: Delayed gadolinium-enhanced MR imaging of cartilage of the MCP joints is feasible at 3.0 T. Delayed gadolinium-enhanced MR imaging of cartilage may help to assess cartilage degeneration in morphologically normal-appearing MCP II and III cartilage in patients with RA.

MRI morphometry, cartilage damage and impaired function in the follow-up after slipped capital femoral epiphysis.

OBJECTIVE: To assess rotation deficits, asphericity of the femoral head and localisation of cartilage damage in the follow-up after slipped capital femoral epiphysis (SCFE). MATERIALS AND METHODS: Magnetic resonance imaging studies were obtained in adult patients with a history of SCFE. A total of 35 hips after SCFE in 26 patients (mean age 24.1 +/- 6.5, mean follow-up 11.9 +/- 6.1 years) were evaluated. The control group comprised 20 healthy hips from 10 young adults with an average age of 23.9 +/- 3.7 years. The MR protocol included a T1-weighted sequence with a 3D volumetric interpolated breath-hold sequence and a radial 2D proton density-weighted sequence around the femoral neck. Images were evaluated for alpha angle and cartilage damage in five positions around the femoral head. Hip function was evaluated at the time of MRI and correlated with MRI results. Mann-Whitney U test and Spearman's correlation coefficient were used for statistical analysis. RESULTS: In the hips after SCFE alpha angles were significantly increased in the anterosuperior (74.1 degrees +/- 18.8 degrees ) and superior (72.5 degrees +/- 21.5 degrees ) positions and decreased in the posterior position (25.0 degrees +/- 7.2 degrees ). Cartilage damage was dominant in the anterosuperior and superior positions. Impaired rotation significantly correlated with increased anterosuperior, superior and posterosuperior alpha angles. CONCLUSION: The data support an anterosuperior and superior cam-type deformity of the femoral head-neck junction in the follow-up after SCFE. MRI after SCFE can be used to assess anterosuperior and superior alpha angles, since the anterior alpha angle by itself may underestimate asphericity and is not associated with rotation deficits.

Zonal T2* and T1Gd assessment of knee joint cartilage in various histological grades of cartilage degeneration: an observational in vitro study.

OBJECTIVES: Accurate assessment of cartilage status is increasingly becoming important to clinicians for offering joint preservation surgeries versus joint replacements. The goal of this study was to evaluate the validity of three-dimensional (3D), gradient-echo (GRE)-based T2* and T1Gd mapping for the assessment of various histological severities of degeneration in knee joint cartilage with potential implications for clinical management. METHODS: MRI and histological assessment were conducted in 36 ex vivo lateral femoral condyle specimens. The MRI protocol included a 3D GRE multiecho data image combination sequence in order to assess the T2* decay, a 3D double-echo steady-state sequence for assessment of cartilage morphology, and a dual flip angle 3D GRE sequence with volumetric interpolated breathhold examination for the T1Gd assessment. The histological sample analysis was performed according to the Mankin system. The data were then analysed statistically and correlated. RESULTS: We observed a significant decrease in the T2* and T1Gd values with increasing grades of cartilage degeneration (p<0.001) and a moderate correlation between T2* (r=0.514)/T1Gd (r=0.556) and the histological grading of cartilage degeneration (p<0.001). In addition, we noted a zonal variation in the T2* and T1Gd values reflecting characteristic zonal differences in the biochemical composition of hyaline cartilage. CONCLUSIONS: This study outlines the potential of GRE-based T2* and T1Gd mapping to identify various grades of cartilage damage. Early changes in specific zones may assist clinicians in identifying methods of early intervention involving the targeted joint preservation approach versus moving forward with unicompartmental, bicompartmental or tricompartmental joint replacement procedures. TRIAL REGISTRATION NUMBER: DRKS00000729.

Quantitative T2(*) assessment of knee joint cartilage after running a marathon.

OBJECTIVE: To study the effect of repetitive joint loading on the T2(*) assessment of knee joint cartilage. MATERIALS AND METHODS: T2(*) mapping was performed in 10 non-professional marathon runners (mean age: 28.7±3.97 years) with no morphologically evident cartilage damage within 48h prior to and following the marathon and after a period of approximately four weeks. Bulk and zonal T2(*) values at the medial and lateral tibiofemoral compartment and the patellofemoral compartment were assessed by means of region of interest analysis. Pre- and post-marathon values were compared. RESULTS: There was a small increase in the T2(*) after running the marathon (30.47±5.16ms versus 29.84±4.97ms, P<0.05) while the T2(*) values before the marathon and those after the period of convalescence were similar (29.84±4.97ms versus 29.81±5.17ms, P=0.855). Regional analyses revealed lower T2(*) values in the medial tibial plateau (P<0.001). CONCLUSIONS: It appears that repetitive joint loading has a transient influence on the T2(*) values. However, this effect is small and probably not clinically relevant. The low T2(*) values in the medial tibial plateau may be related to functional demand or early cartilage degeneration.

T2* mapping of acetabular and femoral hip joint cartilage at 3 T: a prospective controlled study.

OBJECTIVES: The aim of this study was to identify the pattern of T2* values in acetabular and femoral head cartilage in morphologically normal and abnormal zones at 3 T. MATERIALS AND METHODS: Twenty-nine patients (mean [SD] age, 30.8 [8.8] years) with symptomatic femoroacetabular impingement and suspected cartilage damage (study group) and 35 healthy, asymptomatic volunteers (mean [SD] age, 24.9 [2.1] years) with no obvious history of hip diseases or abnormalities (control group) were included. Magnetic resonance imaging was performed at 3 T using a 3-dimensional (3D) double-echo steady-state sequence for grading cartilage morphologically and a 3D multiecho data image combination sequence for T2* assessment. Statistical assessment included the Student t test to reveal differences between mean T2* values of the study group and the control group. One-way analysis of variance was used to identify any statistically significant differences between the T2* values in various grades (modified Outerbridge score system) of cartilage damage within the study group. RESULTS: Significant differences were noted between the T2* values in the study group and the control group (P < 0.001). We also noted a significant drop in T2* in accordance with the morphologic damage in the study group (P < 0.001). The largest drop in T2* was found between morphologically normal-appearing cartilage (grade 0; T2*, 25.2 milliseconds) and grade I changes (T2*, 18.1 milliseconds) (P < 0.001). CONCLUSIONS: In combination with a 3-T system, T2* mapping offers unique advantages such as high image resolution and the ability of 3D biochemically sensitive cartilage evaluation in the hip joint without the need for contrast medium. Given these advantages, we believe that T2* mapping is another welcome addition to the rapidly evolving era of hip cartilage biochemical imaging. Further studies are necessary that involve a diagnostic histological analysis as gold standard for comparison.

Prospectively ECG-triggered high-pitch spiral acquisition for cardiac CT angiography in routine clinical practice: initial results.

PURPOSE: This study was conducted to evaluate the mode of application, image quality (IQ), and radiation exposure resulting from introduction of a prospectively electrocardiogram-triggered high-pitch cardiac computed tomography angiography (CTA) acquisition mode into routine clinical practice. MATERIALS AND METHODS: A total of 42 prospectively triggered cardiac CTAs were conducted on 34 patients (11 female, 23 male; mean age 56 ± 15 y) using a high-pitch mode (pitch 3.4) on a dual-source CT. In 8 of these patients with higher heart rates or occasional premature ventricular contractions, 2 immediately subsequent CTAs were performed ("double flash protocol"). Subjective IQ was assessed for coronary arteries using a 4-point scale (1=unevaluable to 4=excellent). Contrast-to-noise ratio (CNR) was measured in 9 locations. CT Dose Index and dose-length product were obtained, and the patients' effective dose was calculated. RESULTS: Mean effective doses were 2.6 ± 1.4 mSv (range: 1.1 to 6.4) for the entire cardiac examination and 1.4 ± 0.7 mSv (0.4 to 3.1) for individual high-pitch cardiac CTA. z-coverage ranged from 9.9 cm in a native coronary CTA to 31.4 cm in a bypass graft case. The overall subjective IQ was good to excellent (mean score: 3.5), with 1.5% unevaluable coronary segments. The "double flash protocol" resulted in a fully diagnostic CT study in all cases just after taking both scans into consideration. The mean CNR of all locations was 19.7 ± 2.6. CONCLUSION: Prospectively electrocardiograph-triggered high-pitch-mode cardiac CTA is a feasible and promising technique in clinical routine, allowing for evaluation of coronaries at good-to-excellent IQ and providing high CNR and minimal radiation doses. The "double flash protocol" might become a more robust tool in patients with elevated heart rates or premature ventricular contractions.

Minimally invasive catheter procedures to assist complicated pacemaker lead extraction and implantation in the operating room.

We report on percutaneous catheter procedures in the operating room (OR) to assist complicated manual extraction or insertion of pacemaker (PM) and implantable cardioverter defibrillator leads. We retrospectively reviewed complicated PM revisions and implantations performed between 2004 and 2009 that required percutaneous catheter procedures performed in the OR. The type of interventional procedure, catheter and retrieval system used, venous access, success rates, and procedural complications were analyzed. In 41 (12 female and 29 male [mean age 62 ± 17 years]) of 3021 (1.4%) patients, standard manual retrieval of old leads or insertion of new leads was not achievable and thus required percutaneous catheter intervention for retrieval of misplaced leads and/or recanalisation of occluded central veins. Thirteen of 18 (72.2%) catheter-guided retrieval procedures for misplaced (right atrium [RA] or ventricle [RV; n = 3], superior vena cava [n = 2], brachiocephalic vein [n = 5], and subclavian vein [n = 3]) lead fragments in 16 patients were successful. Percutaneous catheter retrieval failed in five patients because there were extremely fixed or adhered lead fragments. Percutaneous transluminal angiography (PTA) of central veins for occlusion or high-grade stenosis was performed in 25 patients. In 22 of 25 patients (88%), recanalization of central veins was successful, thus enabling subsequent lead replacement. Major periprocedural complications were not observed. In the case of complicated manual PM lead implantation or revision, percutaneous catheter-guided extraction of misplaced lead fragments or recanalisation of central veins can be performed safely in the OR, thus enabling subsequent implantation or revision of PM systems in the majority of patients.

Where does it lead? Imaging features of cardiovascular implantable electronic devices on chest radiograph and CT.

Pacemakers and implantable cardioverter defibrillators (ICDs) are being increasingly employed in patients suffering from cardiac rhythm disturbances. The principal objective of this article is to familiarize radiologists with pacemakers and ICDs on chest radiographs and CT scans. Therefore, the preferred lead positions according to pacemaker types and anatomic variants are introduced in this study. Additionally, the imaging features of incorrect lead positions and defects, as well as complications subsequent to pacemaker implantation are demonstrated herein.

Voxel-based analyses of magnetization transfer imaging of the brain in hepatic encephalopathy.

AIM: To evaluate the spatial distribution of cerebral abnormalities in cirrhotic subjects with and without hepatic encephalopathy (HE) found with magnetization transfer imaging (MTI). METHODS: Nineteen cirrhotic patients graded from neurologically normal to HE grade 2 and 18 healthy control subjects underwent magnetic resonance imaging. They gave institutional-review-board-approved written consent. Magnetization transfer ratio (MTR) maps were generated from MTI. We tested for significant differences compared to the control group using statistical non-parametric mapping (SnPM) for a voxel-based evaluation. RESULTS: The MTR of grey and white matter was lower in subjects with more severe HE. Changes were found in patients with cirrhosis without neurological deficits in the basal ganglia and bilateral white matter. The loss in magnetization transfer increased in severity and spatial extent in patients with overt HE. Patients with HE grade 2 showed an MTR decrease in white and grey matter: the maximum loss of magnetization transfer effect was located in the basal ganglia [SnPM (pseudo-)t = 17.98, P = 0.0001]. CONCLUSION: The distribution of MTR changes in HE points to an early involvement of basal ganglia and white matter in HE.