"Long-term MRI findings in Ankylosing spondylitis patients treated with TNF inhibitors for a decade".

OBJECTIVE: This study aims to evaluate the active and chronic lesions in sacroiliac joints and lumbar spine over a decade of TNFi therapy in patients with AS. METHODS: The study enrolled patients with AS under treatment with a TNFi for over a decade. The patients underwent a new MRI scan of their lumbar spine and sacroiliac joint (SIJ). Two readers evaluated all images. Inflammation of SIJ (SIS), SIJ structural damage (SSS) including Fat Metaplasia, Erosions, Backfill and Ankylosis, and Spondyloarthritis Research Consortium of Canada Bone marrow edema (SPARCC) spine score were recorded. RESULTS: In the study, 15 patients were included, with 80% being male. The mean age during their first MRI was 38.1 (± 11.9) years old, and the majority (86.7%) tested positive for HLA-B27. While TNFi improved both BASDAI and BASFI scores, there was a noticeable increase in MRI acute lesions in the SIJ over time, where the median score increased from 0 (0-4) to 3 (0-10) after ten years (p = 0.028). After a decade of treatment, the median SPARCC spine score also increased from 0 (0-9) to 5 (0-16), p = 0.093. Finally, it was observed that there was a significant positive correlation between ESR and SIS erosions in cases of chronic lesions (r = 0.819, p < 0.001). CONCLUSIONS: While TNFi have significantly improved the treatment of AS, this study shows that acute lesions can still develop despite treatment. A personalized approach that adapts MRI assessment to each patient's specific requirements may help detect changes early and enable doctors to intervene promptly to prevent further damage.

Pituitary gland height evaluated with magnetic resonance imaging in premature twins: the impact of growth and sex.

BACKGROUND: Pituitary gland height reflects secretory activity of the hypothalamo-pituitary axis. OBJECTIVE: To assess the cumulative impact of fetal growth and sex on pituitary gland height in premature twins, dissociated from prematurity. MATERIALS AND METHODS: A retrospective study was conducted, assessing the pituitary gland height in 63 pairs of preterm twins, measured from T1-weighted magnetic resonance imaging (MRI). Auxological parameters, including body weight, body length, and head circumference, at birth and at the time of MRI, were used as proxies for fetal and postnatal growth, respectively. The study population was divided into two groups, using corrected age at around term equivalent as the cutoff point. Statistical analysis was performed using mixed-effects linear regression models. RESULTS: When pituitary gland height was evaluated at around term equivalent, a greater pituitary gland height, suggesting a more immature hypothamo-pituitary axis, was associated with the twin exhibiting lower auxological data at birth. The same association was observed when body weight and length at MRI were used as covariants. In the group evaluated after term equivalent, a smaller pituitary gland height, suggesting a more mature hypothamo-pituitary axis, was associated with male sex. This difference was observed in twin pairs with higher average body weight at birth, and in babies exhibiting higher auxological data at MRI. CONCLUSION: After isolating the effect of prematurity, at around term equivalent, pituitary gland height reflects the cumulative impact of fetal growth on the hypothalamo-pituitary axis. Subsequently, pituitary gland height shows effects of sex and of fetal and postnatal growth.

Proton MR Spectroscopy in Assessing the Biochemical Milieu of Human Testes.

Proton magnetic resonance spectroscopy (MRS), considered a connection between metabolism and anatomic and functional information provided by standard MRI, gives information on various tissue metabolites and their pathologic changes. Recently, proton MRS has been added as an adjunct tool to the multiparametric protocol of scrotal MRI, providing a new insight into the extremely complex biochemical milieu of normal and abnormal testes. This article reviews proton MR spectra of normal testes, showing age and bilateralism dependence. Disturbances of various metabolic pathways in testes of infertile men resulting in alterations of metabolite peaks are discussed. Preliminary data on proton MR spectra of testicular mass lesions are presented. LEVEL OF EVIDENCE: 5. TECHNICAL EFFICACY STAGE: 5.

Volumetric apparent diffusion coefficient histogram analysis of the testes in nonobstructive azoospermia: a noninvasive fingerprint of impaired spermatogenesis?

OBJECTIVES: To explore the association between testicular volumetric apparent diffusion coefficient (ADC) histogram analysis metrics and histologic categories in nonobstructive azoospermia (NOA). The role of ADC histogram analysis in predicting the presence of spermatozoa, prior to testicular sperm extraction (TESE), was also investigated. METHODS: Forty-one NOA men and 17 age-matched controls underwent scrotal MRI with diffusion-weighted imaging. Histogram analysis of ADC data of the whole testis was performed. Metrics including mean, standard deviation, median, mode, 25th percentile, 75th percentile, skewness, kurtosis, and entropy of volumetric ADC histograms were calculated. Nonparametric statistical tests were used to assess differences in ADC histogram parameters between NOA histologic categories (hypospermatogenesis, severe hypospermatogenesis, early maturation arrest, and Sertoli cell-only syndrome) and normal testes and, between NOA with positive and negative sperm retrieval. RESULTS: Normal testes had a lower mean, median, mode, 25th percentile (p < 0.001), and 75th percentile of ADC (p = 0.001), compared to NOA histologic phenotypes. NOA with hypospermatogenesis had a lower 25th percentile of ADC compared to NOA with severe hypospermatogenesis. Regression analysis revealed that the 25th percentile of ADC had a moderately negative correlation with NOA histologic phenotype. The median ADC proved the most significant metric (p = 0.007) to predict the presence of sperm. CONCLUSIONS: Testicular volumetric ADC histogram parameters may contribute in the identification of the subpopulation of NOA men with a specific type of spermatogenic arrest. KEY POINTS: • Volumetric ADC histogram analysis metrics may be used as noninvasive markers of impaired spermatogenesis in nonobstructive azoospermia. • The 25th percentile of ADC proved useful in discriminating between NOA testes with hypospermatogenesis and severe hypospermatogenesis. • The median ADC proved the most significant parameter to predict the presence of viable spermatozoa prior to TESE.

Structural and functional brain connectivity in moderate-late preterm infants with low-grade intraventricular hemorrhage.

PURPOSE: Brain functional connectivity (FC) changes and microstructural abnormalities are reported in infants born moderate and late preterm (MLPT). We evaluated the effect of low-grade (grades I, II) intraventricular hemorrhage (IVH) in MLPT babies on brain structural connectivity (SC) and FC. METHODS: Babies born MLPT between January 2014 and May 2017 underwent brain ultrasound (US) at 72 h and 7 days after birth, and MRI at around term equivalent. The MRI protocol comprised T1- and T2-weighted sequences, diffusion tensor imaging (DTI), and resting-state functional MRI (fMRI). SC and FC were assessed using graph analysis. RESULTS: Of 350 MLPT neonates, 15 showed low-grade IVH on US at 72 h, for which brain MRI was available in 10. These 10 infants, with mean gestational age (GA) 34.0 ± 0.8 weeks, comprised the study group, and 10 MLPT infants of mean GA 33.9 ± 1.1 weeks, with no abnormalities on brain US and MRI, were control subjects. All study subjects presented modularity, small world topology, and rich club organization for both SC and FC. The patients with low-grade IVH had lower FC rich club coefficient and lower SC betweenness centrality in the left frontoparietal operculum, and lower SC rich club coefficient in the right superior orbitofrontal cortex than the control subjects. CONCLUSIONS: Topological and functional properties of mature brain connectivity are present in MLPT infants. IVH in these infants was associated with structural and functional abnormalities in the left frontoparietal operculum and right orbitofrontal cortex, regions related to language and cognition.

Vitamin D Deficiency as a Risk Factor for Myocardial Ischemia.

Background and Objectives: Vitamin D (Vit D) deficiency has been implicated in various conditions, including cardiovascular disease. The purpose of this retrospective study was to investigate the incidence of patients with myocardial ischemia in relation to their serum levels of vitamin D. Materials and Methods: A 64-month search (January 2016 to April 2021) in our database of the Nuclear Medicine Laboratory revealed 113 patients who had both myocardial perfusion imaging with single photon emission computed tomography (MPI SPECT) and Vit D measurements. MPI SPECT obtained myocardial images during both stress (summed stress score, SSS) and rest (summed rest score, SRS). Abnormal MPI SPECT was when the SSS was ≥4. Vit D was determined by radioimmunoassay (RIA). Patients with Vit D values <10 ng/mL, 10-29 ng/mL and ≥30 ng/mL were defined as having a deficiency, insufficiency and sufficiency, respectively. Results: Among patients, 46/113 (40.7%) were male and 67/113 (59.3%) were female. Abnormal MPI was found in 58/113 (51.3%) patients. Vit D deficiency was noted in 20/113 (17.7%) patients, insufficiency in 86/113 (76.1%) patients, and normal Vit D was noted in only 7/113 (6.2%) patients. Sixteen of the 20 patients (80%) with Vit D deficiency, and 38/86 (44.2%) with insufficiency had an abnormal MPI SPECT. In contrast, only 1/7 (14.3%) patients with sufficient Vit D levels had an abnormal MPI SPECT. The Mann-Whitney U-test showed that ischemia reduced the values of Vit D. Correlation analysis showed a negative association of Vit D levels with SSS (rho = -0.232, p = 0.014) and SRS (rho = -0.250, p = 0.008). Further evaluation with a Vit D cut off 20 ng/mL retrieved no statistical significance. Finally, Vit D and gender were independently associated with myocardial ischemia. Conclusions: Low Vit D levels may represent a risk factor for myocardial ischemia.

In vivo biochemical investigation of spermatogenic status: 1H-MR spectroscopy of testes with nonobstructive azoospermia.

OBJECTIVES: To evaluate the biochemical milieu in testes with nonobstructive azoospermia (NOA) by using proton MR spectroscopy (1H-MRS) in detecting differences in testicular metabolites between histological stages of NOA and in assessing the possible presence of spermatozoa before microdissection testicular sperm extraction (mTESE). METHODS: Forty-nine NOA men and fifty age-matched controls were included in this prospective study. A single-voxel point-resolved spectroscopy sequence with TR/TE (2000/25 ms) was used. NOA testes were classified using the higher Johnsen score (hJS) (group 1, hJS ≥ 8; and group 2, hJS < 8). Nonparametric statistical tests were used to assess differences in normalized metabolite concentrations, defined as ratios of the metabolite concentrations versus creatine concentration between (a) NOA and controls, (b) NOA groups, and (c) NOA with positive and negative sperm retrieval. RESULTS: Normalized concentrations of total choline (median 0.396 vs 1.09 mmol/kg, p = 0.002), myo-inositol (median 1.985 vs 3.19 mmol/kg, p = 0.002), and total lipids and macromolecules (TLM) resonating at 0.9 ppm (median 0.962 vs 2.43 mmol/kg, p = 0.024), 1.3 ppm (median 4.88 vs 10.7 mmol/kg, p = 0.043), and 2.0 ppm (median 2.33 vs 5.96 mmol/kg, p = 0.007) were reduced in NOA testes compared with controls. Decreased concentrations of TLM 2.0 (median 3.755 vs 0.436 mmol/kg, p = 0.043) were found in group 2 compared with group 1. Increased normalized concentrations of glutamate were observed in NOA testes with failed sperm retrieval (median 0.321 vs 0.000 mmol/kg, p = 0.028). CONCLUSIONS: 1H-MRS provides metabolic information about the testis in NOA patients and assesses spermatogenic status before mTESE. KEY POINTS: • NOA testes differed from age-matched controls, in terms of reduced normalized concentrations of tChol, mI, and lipids. • TLM 2.0 peaks were found useful in the identification of NOA testes with the presence of foci of advanced spermatogenesis up to the haploid gamete stage. • Glu proved a reliable metabolic signature of spermatogenesis in NOA population by assessing the possible presence of sperm after mTESE.

Pediatric minor head injury imaging practices: results from an ESPR survey.

PURPOSE: Computed tomography (CT) for minor head injury exposes a large number of children to ionizing radiation, with an associated increased lifetime risk of malignancy. To study imaging practices for children with minor head injury and the level of awareness of radiologists of the current clinical decision rules for minor traumatic brain injury (TBI). METHODS: A questionnaire consisting of 17 questions was distributed electronically to 472 ESPR members. The questionnaire covered demographic information, employment status, years of experience and the current practice setting of the participants, the number of CTs performed for pediatric head trauma, awareness of clinical decision rules and use of shielding, pediatric CT protocol and MRI. RESULTS: The response rate was 18.4%. The majority of participants was aged over 50 years and was full-time consultants. Regarding decision rules, 73.8% of respondents cited the NICE head injury guidelines, and 79% reported that the decision to perform CT was agreed between specialists. Shielding was used by 58.3% and 67.4% applied a specific pediatric protocol. MRI was not used for pediatric head trauma by 70.6% of respondents, although always available in 68.6% of cases. The reported obstacles to MRI use were machine availability (42.7%), the long acquisition time (39%) and patients' intolerance (18.3%), and less frequently the cost and the need for sedation. CONCLUSION: There is room for decreasing the use of CT for pediatric minor TBI. The use of shielding and application of pediatric CT protocols constitute areas for improvement.

Functional connectivity and microstructural changes of the brain in primary Sjögren syndrome: the relationship with depression.

BACKGROUND: Fatigue and depression are among the most common manifestations of primary Sjögren syndrome (pSS), but information is lacking on the relationship with brain function and microstructural changes. PURPOSE: To investigate microstructural changes and brain connectivity in pSS, and to evaluate their relationship with fatigue and depression. MATERIAL AND METHODS: The study included 29 patients with pSS (mean age 61.2 ± 12.1 years; disease duration 10.5 ± 5.9 years) and 28 controls (mean age 58.4 ± 9.2 years). All the patients completed the Beck's depression and Fatigue Assessment Scale questionnaires. The imaging protocol consisted of: (i) standard magnetic resonance imaging (MRI) pulse sequences (FLAIR, 3D T1W); (ii) a diffusion tensor imaging pulse sequence; and (iii) a resting state functional MRI pulse sequence. Resting state brain networks and maps of diffusion metrics were calculated and compared between patients and controls. RESULTS: Compared with the controls, the patients with pSS and depression showed increased axial, radial, and mean diffusivity and decreased fractional anisotropy; those without depression showed decreased axial diffusivity in major white matter tracts (superior longitudinal fasciculus, inferior longitudinal fasciculus, corticospinal tract, anterior thalamic radiation, inferior fronto-occipital fasciculus, cingulum, uncinate fasciculus, and forceps minor-major). Decreased brain activation in the sensorimotor network was observed in the patients with pSS compared with the controls. No correlation was found between fatigue and structural or functional changes of the brain. CONCLUSION: pSS is associated with functional connectivity abnormalities of the somatosensory cortex and microstructural abnormalities in major white matter tracts, which are more pronounced in depression.

Are there differences in the biochemical profile of bilateral normal testes? A 3.0 T 1H-MR spectroscopy study.

Bilateral normal testes asymmetry represents an interesting phenomenon. The aim was to assess possible differences in the biochemical profile of bilateral normal testes by 3.0 T proton magnetic resonance spectroscopy (1H-MRS). Twenty-one men were examined with scrotal 3.0 T MRI, including a single-voxel point-resolved spectroscopy sequence. MR spectra were obtained by placing a volume of interest in the middle of each normal testis. Normalised metabolite concentrations, defined as ratios of the calculated metabolite concentrations relative to creatine (Cr) concentration, were compared between bilateral normal testes using Mann-Whitney U test. 1H-MRS allowed the detection of certain testicular metabolites, including total choline, Cr, myo-inositol, Glx, total lipids and macromolecules resonating at 0.9, 1.3 and 2.0 ppm. Normal left testis had higher median normalised concentrations of Glx (p = .002) and lactate (p = .041) compared with the normal right testis. Differences in concentrations of Glx were attributed to differences in glutamate (p = .020). Normal testes asymmetry is confirmed in this study by differences in the biochemical testicular profile, as assessed by 3.0 T 1H-MRS. Increase in levels of glutamate and lactate in normal left testis should be correlated with changes in metabolic pathways, specifically glycometabolism and amino acid metabolism.

Testicular Apparent Diffusion Coefficient and Magnetization Transfer Ratio: Can These MRI Parameters Be Used to Predict Successful Sperm Retrieval in Nonobstructive Azoospermia?

OBJECTIVE. The aim of our study was to assess if testicular apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR) can be used as MRI parameters to predict the presence of spermatozoa retrieved after microdissection testicular sperm extraction (mTESE) in men with nonobstructive azoospermia (NOA). MATERIALS AND METHODS. The study included 49 men with NOA and 45 age-matched control subjects. Participants underwent scrotal MRI between June 2013 and January 2017, 1 day before mTESE. Testicular volume (TV), ADC, and MTR were measured. NOA testes were classified as follows: group 1, testes with higher Johnsen score of ≥ 8; and group 2, testes with higher Johnsen score of < 8. Nonparametric statistical tests were used to assess differences in TV, ADC, and MTR between men with NOA and control subjects, the two NOA groups, and NOA testes with positive sperm retrieval and NOA testes with negative sperm retrieval. RESULTS. TV (p < 0.001) was reduced and both ADC (p < 0.001) and MTR (p = 0.013) were increased in NOA testes compared with normal testes. A positive correlation between higher Johnsen score and TV (p < 0.001) and a negative correlation between higher Johnsen score and both ADC (p = 0.015) and MTR (p = 0.003) were found. TV (p < 0.001) was reduced in NOA testes with failed sperm retrieval compared with NOA testes with positive sperm retrieval. On the contrary, ADC (p = 0.011) and MTR (p = 0.045) were significantly increased in NOA testes with negative sperm retrieval. CONCLUSION. On the basis of our preliminary data, TV, ADC, and MTR might represent useful MRI parameters in the workup of patients with NOA by helping to predict the presence of spermatozoa after mTESE.

Functional and structural connectivity of the brain in very preterm babies: relationship with gestational age and body and brain growth.

BACKGROUND: Structural and functional changes of the brain have been reported in premature babies. OBJECTIVE: To evaluate the relationship of functional and structural connectivity with gestational age, body growth and brain maturation in very preterm babies. MATERIALS AND METHODS: We studied 18 very preterm babies (gestational age: mean ± standard deviation, 29.7±1.7 weeks). We examined functional connectivity by multivariate pattern analysis of resting-state functional MRI data. We assessed structural connectivity by analysis of diffusion tensor imaging data and probabilistic tractography. RESULTS: The average functional connectivity of the medial orbitofrontal cortex with the rest of the brain was positively associated with gestational age (P<0.001). Fractional anisotropy of the right inferior fronto-occipital fasciculus was positively associated with head circumference at term-equivalent age. Structural connectivity of the inferior fronto-occipital fasciculus with the medial orbitofrontal cortex was positively associated with head circumference at term-equivalent age. Body weight at term-equivalent age was the only independent predictor of average structural connectivity of the medial orbitofrontal cortex with the rest of the brain (P=0.020). CONCLUSION: Structural and functional connectivity of the medial orbitofrontal cortex with the rest of the brain depend on body growth and degree of prematurity, respectively.

Diffusion tensor imaging as an adjunct tool for the diagnosis of varicocele.

A noninvasive imaging technique providing information about testicular dysfunction in testes with varicocele would be useful. The aim is to measure the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in testes of infertile men with varicocele and to assess interobserver agreement. Sixteen infertile men with varicocele and 14 age-matched controls underwent 1.5 T diffusion tensor imaging (DTI) MRI. Testicular ADC and FA were measured by two radiologists independently. Parametric and nonparametric statistical tests were applied to compare between the ADC and FA of testes with varicocele and normal testes. Interobserver agreement was evaluated. The interobserver variability for ADC (0.915) and FA (0.948) was very good. No differences in ADC (p = 0.294) were found between the two groups. FA was significantly lower in testes with varicocele compared to age-matched controls (p < 0.001). An optimal cut-off of FA 0.08 was found for the diagnosis of varicocele (sensitivity = 88%, specificity = 93.5%, positive predictive value = 91.6% and negative predictive value = 90.6%). Based on our results, FA is useful for the diagnosis of testes in infertile men with varicocele, with very good interobserver agreement. Therefore, DTI may be used as a noninvasive imaging tool in the work-up of varicocele.

Diffusion tensor imaging parameters in testes with nonobstructive azoospermia.

BACKGROUND: The development of noninvasive imaging parameters having the capacity to identify the population of men with nonobstructive azoospermia (NOA) where a successful sperm retrieval outcome is of great clinical significance. PURPOSE/HYPOTHESIS: To assess differences of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in NOA testes with impaired spermatogenesis and the possible association with the presence of spermatozoa after testicular sperm extraction (TESE). STUDY TYPE: Retrospective. POPULATION: Twenty NOA men (35 testes) and 21 age-matched controls (36 testes). FIELD STRENGTH/SEQUENCE: 1.5T, T1 WI-SE T2 WI-FSE FS SS-EP-DTI. ASSESSMENTS: The MRI data were analyzed by two radiologists in consensus. The average ADC and FA of testicular parenchyma was measured. NOA testes were classified as NOA with higher Johnsen score (JS) ≥8 (group 1) and JS <8 (group 2). STATISTICAL TESTS: Parametric and nonparametric statistical tests were used to compare ADC and FA between NOA groups and normal testes (group 3) and to evaluate a possible association with the presence of spermatozoa after TESE. RESULTS: Differences in ADC were found between groups 1 and 2 (P = 0.043) and groups 2 and 3 (P = 0.004), but not between groups 1 and 3 (P = 0.418). Higher values of FA were found both in NOA testes with JS ≥8 (P < 0.001) and JS <8 (P < 0.001) compared to controls. ADC (P = 0.096) and FA (P = 0.516) did not demonstrate differences in NOA testes with or without spermatozoa at TESE. DATA CONCLUSION: Both ADC and FA are increased in NOA testes compared to a normal population. ADC was proven to be a more useful diagnostic adjunct tool in the identification of the population of NOA men with foci of advanced spermatogenesis. However, DTI parameters were not predictive of sperm retrieval after TESE. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1318-1325.

MR Spectra of Normal Adult Testes and Variations with Age: Preliminary Observations.

OBJECTIVES: The aim was to determine the proton MR (1H-MR) spectra of normal adult testes and variations with age. METHODS: Forty-one MR spectra of normal testes, including 16 testes from men aged 20-39 years (group I) and 25 testes from men aged 40-69 years (group II), were analyzed. A single-voxel point-resolved spectroscopy sequence (PRESS), with TR/TE: 2000/25 ms was used. The volume of interest was placed to include the majority of normal testicular parenchyma. Association between normalized metabolite concentrations, defined as ratios of the calculated metabolite concentrations relative to creatine concentration, and age was assessed. RESULTS: Quantified metabolites of the spectra were choline (Cho), creatine (Cr), myo-inositol (mI), scyllo-inositol, taurine, lactate, GLx compound, glucose, lipids, and macromolecules resonating at 0.9 ppm (LM09), around 20 ppm (LM20), and at 13 ppm (LM13). Most prominent peaks were Cho, Cr, mI, and lipids. A weak negative correlation between mI and age (P = 0.015) was observed. Higher normalized concentrations of Cho (P = 0.03), mI (P = 0.08), and LM13 (P = 0.05) were found in group I than in group II. CONCLUSIONS: 1H-MR spectra of a normal adult testis showed several metabolite peaks. A decrease of levels of Cho, mI, and LM13 was observed with advancing age. KEY POINTS: • Single-voxel PRESS MRS of a normal testis is feasible. • 1H-MR spectra of a normal testis showed several metabolite peaks. • Most prominent peaks were Cho, Cr, mI, and lipids. • A decrease of Cho, mI, and LM13 was seen with advancing age.

Magnetization transfer imaging of normal and abnormal testis: preliminary results.

OBJECTIVES: The aim was to determine the magnetization transfer ratio (MTR) of normal testes, possible variations with age and to assess the feasibility of MTR in characterizing various testicular lesions. METHODS: Eighty-six men were included. A three-dimensional gradient-echo MT sequence was performed, with/without an on-resonance binomial prepulse. MTR was calculated as: (SIo-SIm)/(SIo) × 100 %, where SIm and SIo refers to signal intensities with and without the saturation pulse, respectively. Subjects were classified as: group 1, 20-39 years; group 2, 40-65 years; and group 3, older than 65 years of age. Analysis of variance (ANOVA) followed by the least significant difference test was used to assess variations of MTR with age. Comparison between the MTR of normal testis, malignant and benign testicular lesions was performed using independent-samples t testing. RESULTS: ANOVA revealed differences of MTR between age groups (F = 7.51, P = 0.001). Significant differences between groups 1, 2 (P = 0.011) and 1, 3 (P < 0.001) were found, but not between 2, 3 (P = 0.082). The MTR (in percent) of testicular carcinomas was 55.0 ± 3.2, significantly higher than that of benign lesions (50.3 ± 4.0, P = 0.02) and of normal testes (47.4 ± 2.2, P < 0.001). CONCLUSIONS: MTR of normal testes decreases with age. MTR might be helpful in the diagnostic work-up of testicular lesions. KEY POINTS: MTR of normal testes shows age-related changes. Testicular carcinomas have high MTR values. MTR may be useful in the diagnostic work-up of testicular lesions.

Key concepts in MR spectroscopy and practical approaches to gaining biochemical information in children.

Magnetic resonance spectroscopy (MRS) provides independent biochemical information and has become an invaluable adjunct to MRI and other imaging modalities. This review introduces key concepts and presents basic methodological steps regarding the acquisition and the interpretation of proton MRS. We review major brain metabolites and discuss MRS dependence on age, location, echo time and field strength.

Diffusion tensor imaging in children with tuberous sclerosis complex: tract-based spatial statistics assessment of brain microstructural changes.

BACKGROUND: There is evidence of microstructural changes in normal-appearing white matter of patients with tuberous sclerosis complex. OBJECTIVE: To evaluate major white matter tracts in children with tuberous sclerosis complex using tract-based spatial statistics diffusion tensor imaging (DTI) analysis. MATERIALS AND METHODS: Eight children (mean age ± standard deviation: 8.5 ± 5.5 years) with an established diagnosis of tuberous sclerosis complex and 8 age-matched controls were studied. The imaging protocol consisted of T1-weighted high-resolution 3-D spoiled gradient-echo sequence and a spin-echo, echo-planar diffusion-weighted sequence. Differences in the diffusion indices were evaluated using tract-based spatial statistics. RESULTS: Tract-based spatial statistics showed increased axial diffusivity in the children with tuberous sclerosis complex in the superior and anterior corona radiata, the superior longitudinal fascicle, the inferior fronto-occipital fascicle, the uncinate fascicle and the anterior thalamic radiation. No significant differences were observed in fractional anisotropy, mean diffusivity and radial diffusivity between patients and control subjects. No difference was found in the diffusion indices between the baseline and follow-up examination in the patient group. CONCLUSION: Patients with tuberous sclerosis complex have increased axial diffusivity in major white matter tracts, probably related to reduced axonal integrity.