The utility of diffusion-weighted imaging to assess acute renal parenchymal changes due to unilateral ureteral stone obstruction.

Our aim in this study was to evaluate the use of diffusion-weighted imaging (DWI) for acute renal parenchymal changes occurring as a result of unilateral ureteral obstruction due to stones. Twenty four patients with obstructed and opposite unobstructed kidney were enrolled in this prospective study. DWI was used at two different b values (b = 0 s/mm2 and b = 1000 s/mm2). Apparent diffusion coefficient (ADC) measurements were completed on the upper pole, central section and lower pole parenchyma of both kidneys. ADC values were calculated. The unpaired t test was used to assess differences between the groups. The results of measurements identified a reduction in ADC values in obstructed renal parenchyma compared to unobstructed opposite renal parenchyma. The reduction in ADC values was greater in the upper and lower pole parenchyma and was statistically significant (p < 0.001, for both). Diffusion changes in renal parenchyma due to acute unilateral ureteral obstruction linked to stone may be quantitatively shown with DWI. The reduction in ADC values was more pronounced in the upper and lower pole parenchyma.

Diffusion-Weighted Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy Features of Abdominal Viscera in a Patient with Gaucher's Disease.

A 46-year-old woman with Gaucher's disease (GD) consulted our clinic for abdominopelvic magnetic resonance imaging (MRI), as physical examination had revealed hepatosplenomegaly. Upper abdominal MRI showed massive hepatosplenomegaly and innumerable hypointense splenic nodules on T1-weighted images. Diffusion-weighted MRI (DW-MRI) and magnetic resonance spectroscopy (MRS) were performed to liver parenchyma and splenic nodules. MRS revealed lactate, lipid, acetate, and alanine peaks in splenic nodules, and choline, creatine, lipid, myo-inositol-glycine, and lactate peaks in the liver parenchyma. The DW-MRI showed diffusion restriction in splenic nodules. It was concluded that MRI is a reliable method for the diagnosis and follow up of GD. Coupling DW-MRI and MRS allows quantitative evaluation, thereby increasing the efficacy of the method. This is the first report in the literature presenting advanced abdominal MRI findings in GD.

Unusual drainage of the main kidney on accessory kidney.

Patients with an accessory kidney are characterized by an excessive number of kidneys. The ureter of the accessory kidney either drains separately into the bladder or merges with the ureter of the main kidney. In our case, interestingly, the ureter of the left main kidney drained directly into the accessory kidney and the ureter of the latter was the common drainage route for both. The drainage of a normal kidney via the ureter of an accessory kidney has not been reported in the literature, so far. The aim of this report is to present the case with radiological findings and to emphasize the effects of this situation on planned surgical procedures. A 62-year-old female patient had an interesting abnormality on the left collecting system, which was revealed on excretory urography (EU), retrograde urography (RU) and multidetector computed tomography (MDCT). A kinky left ureter, which formed a U shape, was revealed on EU. On MDCT, an accessory kidney was revealed at the anterior aspect of the middle zone of left main kidney. The ureter of the main left kidney drained directly into the accessory kidney. The course of this drainage was confirmed by retrograde urography. An accessory kidney is a rare entity associated with horseshoe kidney, ectopic ureter draining into the vagina, bifid collecting system and coarctation of the aorta. In our case, an unusual association between the ureters of the main and accessory kidneys was revealed, which may have an impact on planned surgery in the groin and retroperitoneal areas.

Cystic adrenal lymphangioma--report of two cases and review of the literature.

Cystic adrenal lymphangiomas are very rare, benign vascular lesions. They are usually found during a work up for abdominal pain or incidentally during imaging studies for an unrelated cause. We report two cases of cystic adrenal lymphangiomas. They presented with flank discomfort, hypertension and flushing. Their laboratory findings were in normal limits. Radiologic imagings showed adrenal cystic neoplasm and the patients underwent adrenelectomy. Histopathologic examination and immunohistochemical findings were consistent with lymphangioma. Cystic lymphangiomas may imitate other adrenal neoplasms and must be kept in mind in the clinical and radiologic differential diagnosis of cystic adrenal lesions.

Advanced MRI findings in patients with breast hamartomas.

PURPOSE: Although it has been stated that breast hamartomas are rare tumors, radiologists frequently encounter them in their daily practices. Fat, glandular and fibrous tissues all produce a mass of disorganized but mature specialized cells. Because hamartomas do not have specific diagnostic histological features, the clinical and radiological findings are important in their diagnosis. The aim of this study is to present the advanced magnetic resonance imaging (MRI) findings of breast hamartomas. MATERIALS AND METHODS: Eight patients with breast hamartomas were examined using MRI techniques in addition to ultrasonographic and/or mammographic findings. RESULTS: Each of the lesions examined showed a gradual enhancement pattern in its time-signal intensity curve on dynamic contrast-enhanced MRI. On MR spectroscopy, water and lipid peaks were detected that resembled normal breast tissue. The diffusion features of the lesions were variable due to the different ratios of the tissue elements constituting them on diffusion-weighted imaging (DWI). CONCLUSION: Advanced MRI findings may clarify diagnoses by providing additional information following sonography, especially in lactating or pregnant women, in whom mammographic examination is not preferred.

Lumbar gossypiboma.

Gossypiboma is a mass formed by a retained surgical sponge and reactive tissue. The cases with gossypiboma are usually asymptomatic or with nonspecific symptoms, which delay diagnosis for months or years after surgery. We describe imaging findings in a 43-year-old woman with a symptomatic retained surgical sponge in a lumbar laminectomy site. Ultrasonography, computed tomography, magnetic resonance imaging (MRI), and diffusion-weighted MRI were performed. Gossypiboma should be considered in the differential diagnosis of a mass in a patient with a history of prior surgery. Diffusion-weighted MRI may provide important data for differential diagnosis of gossypiboma. With diffusion-weighted MRI, gossypiboma may be distinguished from an abscess by its low signal intensity and increased apparent diffusion coefficient (ADC) as compared to high signal intensity with low ADC in cases of abscess.

Diffusion-weighted images differentiate benign from malignant thyroid nodules.

PURPOSE: To reveal the possible role of diffusion-weighted images (DWI) in the differential diagnosis of benign and malignant thyroid nodules by comparing the results of fine-needle aspiration cytology (FNAC). MATERIALS AND METHODS: In an 18-month period (December 2005 to May 2007), 27 cases with benign thyroid nodules with a total of 52 benign nodules, nine cases with thyroid gland malignancy, and 24 healthy control cases were included in the study. Cases that were indicated to undergo to FNAC examination and sent by a clinician for biopsy to the radiology unit were included in the study to assess the cytopathologic confirmation of the clinic, ultrasonographic, and magnetic resonance imaging (MRI) findings. RESULTS: The mean apparent diffusion coefficient (ADC) values of thyroid nodules were 2745.3 +/- 601.1 x 10(-6) mm(2)/s (1605-3899 x 10(-6)mm(2)/s) in the benign group and 695.2 +/- 312.5 x 10(-6)mm(2)/s (165-1330 x 10(-6)mm(2)/s) in the malignant group. Normal thyroid tissues had mean ADC values of 1344.1 +/- 276.4 x 10(-6) mm(2)/s (1015-1764 x 10(-6)mm(2)/s). The ADC values of three subgroups were significantly different (P = 0.0001). A reduced ADC was observed in most types of malignant tumors due to the consequent decrease of the extracellular extravascular space. CONCLUSION: Our preliminary results showed that ADC values of nodules may provide useful data about the nature of a thyroid nodule.

Bilateral anterior inferior iliac spine avulsion in an adolescent soccer player: a typical imitator of malignant bone lesions.

Avulsion fractures are usually diagnosed easily in acutely presented cases. The diagnosis becomes definite if clinical and radiological follow up reflect the fracture's healing phase. A 13-year-old soccer player with bilateral anterior inferior iliac spine (AIIS) avulsion, who had been examined in other institutions with a prediagnosis of malignancy, is reported. Clinically, such cases display the importance of medical management of athletic injuries by specially trained physicians. From the perspective of preventive medicine, the high incidence of AIIS injuries during soccer games, and the bilateral nature of the damage mandate a review of the training programs and shooting techniques for adolescent players.

Microstructural changes in uterine leiomyomas and myometrium: a diffusion-weighted magnetic resonance imaging study.

Although morphological and histopathological changes in uterine leiomyomas have been investigated in detail, the microstructural disruptions could not be studied in the living organism. Diffusion-weighted magnetic resonance imaging (DWI) is a novel tool to assess microstructural changes in vivo. The aim of this study was to investigate and characterize the diffusional property of leiomyomatous tissues with DWI. Sixteen females with a total of 21 leiomyomas were imaged with a 1.5-tesla clinical MR scanner. DWI images of leiomyomas, adjacent myometrial and myometrial tissues of healthy controls were obtained and quantified using apparent diffusion coefficient (ADC) maps. Mean ADC values of these groups were 1,201, 1,684, 1,661 mm(2)/s x 10(-6), respectively. ADC values in leiomyomas were significantly lower than those observed in the myometrium (p < 0.001). Cut-off values produced 91% sensitivity and 100% specificity. As ADC values implied the presence of cytotoxic edema in leiomyomas, the technique was found to be promising in observing temporal variations in leiomyomas and to monitor even the most subtle effects of therapeutic interventions.

Diffusion-weighted imaging features of brain in obesity.

PURPOSE: Obesity is characterized by an altered distribution of body fluid. However, distribution of fluid (extracellular/intracellular) in brain tissues has not been studied in obese subjects yet. The purpose of this study was to detect possible brain diffusion changes especially in satiety and hunger related centers in obese subjects by diffusion weighted imaging (DWI). METHODS: Conventional MRI and DWI of the brain was obtained from 81 obese patients (obese=68, morbid obese=13) and 29 age-matched, nonobese. The apparent diffusion coefficient (ADC) values were calculated in hypothalamus; amygdala; hippocampal gyrus; thalamus; insula; cingulate gyrus; orbitofrontal, dorsomedial and dorsolateral frontal, middle temporal and occipital cortex; cerebellum; midbrain and corpus striatum. RESULTS: The ADC values of hypothalamus, hippocampal gyrus, amygdala, insula, cerebellum and midbrain were significantly increased in patients (n:81) when compared to nonobese subjects. The ADC values of thalamus, hippocampal gyrus, amygdala, orbitofrontal, occipital, dorsolateral and middle temporal cortex, insula and midbrain were significantly increased in morbid obese when compared to nonobese subjects. The ADC values of orbitofrontal and occipital cortex were significantly higher in morbid obese than the values in the obese. The body mass index positively correlated with ADC values of amygdala, insula, orbitofrontal and middle temporal cortex. CONCLUSION: We observed increased ADC values of distinct locations related to satiety and hunger that suggest altered fluid distribution and/or vasogenic edema in obese subjects. Awareness of this abnormalities in brain tissue composition/function in obesity may contribute to better understanding of the underlying mechanisms.

1H magnetic resonance spectroscopy of the normal testis: preliminary findings.

PURPOSE: The purpose of this study was to determine the pre- and postpubertal 1H magnetic resonance spectroscopic characteristics of the normal testis to establish baseline values for further clinical studies. MATERIALS AND METHODS: The subjects consisted of male volunteers, of whom 19 were prepubertal with ages between 7 and 13 years and 24 were postpubertal with ages between 19 and 39 years. Their testes were evaluated at 1.5 T with magnetic resonance spectroscopy; in addition, testis volumes were measured. Major metabolite peaks were identified and their ratios were calculated. Metabolite differences of testis between pre- and postpubertal age were analyzed. RESULTS: Major constituents of spectra were 3.21 ppm choline and 0.9-1.3 ppm lipid peaks. At the echo time (TE) spectrum of 31 ms, choline/lipid ratios ranged from 0.35 to 8.30 (mean=1.87) in postpubertal males and from 0.06 to 5.45 (mean=0.88) in prepubertal males (P<.013). At the TE spectrum of 136 ms, choline/lipid ratios ranged from 0.66 to 15.42 (mean=4.09) in postpubertal males and from 0.05 to 4.91 (mean=0.9) in prepubertal males (P<.016). CONCLUSIONS: Choline/lipid ratio was higher in the postpubertal period. The existence of higher choline peak in that age group should be due to the initiation of spermatogenesis. The decrease in the lipid peak may represent the effect of testosterone on testicular tissue or may be due to histochemical changes initiated by puberty. The significant decrease in choline/lipid ratio noted after puberty could represent the presence of spermatogenesis. This hypothesis should be evaluated by further studies on postpubertal subjects with impaired spermatogenesis.

Pure uterine lipoma.

Lipomatous tumors of the uterus are unusual, benign neoplasms seen in postmenopausal women. Although many of the mixed-type cases such as lipoleiomyoma and fibrolipoma have been reported, pure uterine lipomas are extremely rare. In the literature, a few cases with pure uterine lipoma have been reported. We first present the advanced magnetic resonance findings of pure uterine lipoma, followed by those of ultrasonography (US) and computed tomography (CT). We markedly detected lipid peaks on the magnetic resonance spectroscopy (MRS) and the apparent diffusion coefficient value to be 0.00 due to chemical-shift effects with diffusion-weighted imaging (DWI). Although pelvic lipomatous tumors can be diagnosed with US and CT, in some cases, further workup may be required to localize the lesion. MRI may yield more valuable data for differential diagnosis. MRS and DWI findings provide additional clues on the nature of the lesion.

Osmotic demyelination syndrome in a 40-day-old infant.

Osmotic demyelination syndrome refers to the myelin destruction of various brain structures that follows osmotic stress. It affects myelinated brain; therefore, it is very rare in babies and it has not been reported in patients younger than 10 months of age. Herein, we present a 40-day-old infant with osmotic demyelination syndrome, along with imaging findings. Her pontine and thalamic lesions regressed during the 10-day treatment course, whereas demyelinated areas in the lentiform nucleus persisted. Magnetic resonance spectroscopy of the latter revealed decreased levels of all major metabolites. Imaging findings remained unchanged after that phase.

Diffusion-weighted imaging evaluation of subtle cerebral microstructural changes in intrauterine fetal hydrocephalus.

OBJECTIVE: Hydrocephalus is an important etiological factor in neurological decline. With the advent of fetal ultrasound, fetal hydrocephalus is now more frequently detected than in the past. Ultrasonography (USG) provides information on general morphology, but microstructural changes that may play a prognostic role are beyond the resolution of that technique. These changes may theoretically be revealed by diffusion-weighted magnetic resonance imaging (DW-MRI). In this study, our preliminary findings of DW-MRI on the hydrocephalic fetuses are presented. MATERIALS AND METHODS: Twelve fetuses with fetal USG diagnosis of hydrocephalus were investigated using a 1.5-T MR scanner. In addition to conventional techniques, DWI was performed. It was obtained using a single-shot echo-planar imaging sequence (TR/TE: 4393/81 ms; slice thickness: 5 mm; interslice gap: 1 mm; FOV: 230 mm; matrix size: 128x256; b values: 0 and 1000 s/mm2). Apparent diffusion coefficient (ADC) values were measured in the white matter of the periventricular frontal and occipital lobes, basal ganglia, thalamus, centrum semiovale and cerebrospinal fluid in the lateral ventricle. These values were compared with the normal prenatal ADC values from a radiological study published in the literature. RESULTS: All fetuses had moderate or severe bilateral supratentorial ventricular dilatation that was compatible with hydrocephalus. On conventional T1- and T2-weighted imaging, cerebral parenchyma had normal signal pattern and ADC values were significantly lower than those reported for fetuses with normal brain. These values were lower in hydrocephalic fetuses with statistical significance (P<.05-.01). CONCLUSION: DWI is a sensitive technique to investigate cerebral microstructure. The reduction in cerebral blood flow and alterations in cerebral energy metabolism in cases with hydrocephalus have been shown before. Changes in cerebral blood flow and energy metabolism, as a consequence of cerebral compression, may occur in hydrocephalus. Elevated ventricular pressure may cause cerebral ischemia. The anaerobic glycolysis seen in the hydrocephalic brain tissue by increasing the lactate concentration and intracellular fluid flux may be the reason for the reduced ADC values in hydrocephalic fetuses. However, long-term prospective trials on the correlation of ADC values and neurological outcome are necessary to exploit the full benefit of that novel technique.

Giant axonal neuropathy: diffusion-weighted imaging features of the brain.

Giant axonal neuropathy is a rare autosomal recessive childhood disorder characterized by a peripheral neuropathy and features of central nervous system involvement. Magnetic resonance imaging (MRI) of an 11-year-old boy with giant axonal neuropathy revealed high signal intensity in the white matter of the cerebrum and cerebellum on T(2)-weighted imaging. An apparent diffusion coefficient map revealed increased apparent diffusion coefficient values in the periventricular, deep, and cerebellar white matter, basal ganglia, and thalamus. Increased apparent diffusion coefficient values in distinct locations suggest increased mobility of water molecules in the brain of a patient with giant axonal neuropathy. This finding could indicate a myelin disorder such as demyelination. Diffusion-weighted imaging should be performed to reveal apparent diffusion coefficient changes and determine brain involvement in patients with giant axonal neuropathy.

Clinical outcomes of neonatal hypoxic ischemic encephalopathy evaluated with diffusion-weighted magnetic resonance imaging.

PURPOSE: Detection of early phase neurological deficit in babies with hypoxic-ischemic encephalopathy (HIE) is the most important step to determine the appropriate preventive treatment methods. Diffusion-weighted imaging (DWI) is the most sensitive radiological modality to detect ischemic changes in the brain, in their earliest phase. Herein, we present the results of our study about the role of DWI in the diagnosis and determining the prognosis of HIE in neonates. MATERIALS AND METHODS: The study included 36 cases (4 preterm, 32 term babies) who were diagnosed with HIE within 24 hours of birth and classified according to modified Sarnat staging. They were examined for the presence of neurological sequelae at 3 and 6 months of age with electroencephalography (EEG), visual evoked potential (VEP), brainstem auditory evoked potential (BAEP), and Denver II developmental screening tests. All 36 patients underwent conventional magnetic resonance (MR) imaging and DWI within the first 24 hours of birth; survivors underwent repetitive imaging exams at the end of the first week and then after a month. RESULTS: Seventeen stage I cases (47%), 12 stage II cases (33%), and 7 stage III cases (20%) were detected. DWI obtained within the first 24 hours showed high sensitivity (100%) in detecting the permanent neurological sequelae but with very low specificity (20%). The negative predictive value of DWI in this period was 100%; however, in DWI obtained at the end of the first month, not only its sensitivity was preserved, but its specificity reached 80%. The negative predictive value of DWI in this period was preserved and the positive predictive value improved. The importance of DWI in detecting sequelae at the end of the first month was also demonstrated by McNemar (p=0.250) and Kappa (Kappa=0.719) tests. There was no difference between conventional MR imaging and DWI in detecting sequelae at the end of first month. CONCLUSION: DWI is superior to other imaging modalities in detecting ischemia; not only because of its high sensitivity in the early phase, but also because of its high sensitivity and specificity in the late phase. Moreover, with its high negative predictive value, DWI can be used for excluding the possibility of sequelae development in the early phase of HIE cases for medico-legal purposes.

Diffusion weighted MR findings of brain involvement in tuberous sclerosis.

PURPOSE: Diffusion Weighted Imaging (DWI) is effective in identifying microstructural cerebral parenchymal changes. We studied the diffusion characteristics of hamartomas and normal white matter in cases with tuberous sclerosis (TS). MATERIALS AND METHODS: Diffusion weighted images of 6 TS cases (ages between 3 - 15 years, mean 9.0 years, SD 4.4 years) that presented to our center for magnetic resonance (MR) imaging have been retrospectively evaluated. In addition to 56 non-calcified hamartomas of TS patients, apparent diffusion coefficient (ADC) values measured from frontal, parietal normal white matter, and basal ganglions of TS patients were compared with values obtained from 9 normal subjects (ages 1 - 13 years, mean 8.9 years, SD 3.4 years). Hamartomas were divided into 3 subgroups based on their locations, and the ADC values measured in these groups were compared. RESULTS: ADC values of all hamartomas were between 838 and 2230, with a mean value of 1408 mm (2)/sec x 10(-3) (SD: 273.2); ADC values of the white matter of normal subjects were between 695 and 857, with a mean value of 776.1 mm (2)/sec x 10(-3) (SD: 44.23) (p < 0.0001). ADC values of subependymal nodules, white matter hamartomas, and subcortical tubers were 838-2230 (mean: 1440.5 mm (2)/sec x 10(-3); SD: 526.46), 1046-1622 (mean: 1328.6 mm (2)/sec x 10(-3); SD: 189.4), and 981-1973 (mean: 1417.4 mm (2)/sec x 10(-3); SD: 219.5), respectively (p = 0.666). CONCLUSION: Diffusion characteristics of white matter hamartomas resulting from TS clearly differ from those of normal white matter, but no significant difference was observed in ADC values of these lesions based on their locations. Moreover, the ADC measurements of normal white matter in these cases did not differ from those of the control group, indicating that the disease does not cause a common explicit damage in white matter and central gray matter, other than hamartomas, which can be detected by DWI. DWI may only be used in the differential diagnosis of hamartomas from secondary lesions with T1 and T2W signal intensities similar to those of hamartomas and with different diffusion characteristics.

The effect of intravenous gadolinium-DTPA on diffusion-weighted imaging.

INTRODUCTION: Diffusion-weighted imaging (DWI) is usually performed before injection of intravenous paramagnetic contrast medium. Occasionally, it may be necessary to perform or to repeat DWI after such administration. Our purpose was to evaluate the effect of intravenous gadodiamide (Gd [DTPA-BMA]) on DWI. METHODS: DWI was performed on 88 brain lesions immediately before, immediately after, and 5-10 min following the end of 0.1 mmol/kg Gd [DTPA-BMA] administration. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of the lesions, and the SNRs of normal brain tissue were calculated on b=0 s/mm(2) and b=1,000 s/mm(2) DW images. Apparent diffusion coefficient (ADC) values of the lesions were measured on ADC maps. A paired t-test was used to determine the significance of differences between the values before and after administration of contrast medium. RESULTS: The lesions consisted of 23 intraaxial and 11 extraaxial masses, 19 ischemic strokes, 15 intracranial hemorrhages and 20 demyelinating lesions. Images before and after contrast administration were not significantly different regarding SNRs and CNRs on DWI. This statement was also true for strongly enhanced lesions. However, ADC values significantly decreased after contrast medium injection on early post-contrast DWI in normal brain tissue (1%, P<0.049) and (3%, P<0.008) in lesions. By contrast, on late images, ADC values were normalized. CONCLUSION: Contrast medium injection had significant and time-dependent effects on ADC values. Therefore, only pre-contrast and late DW images should be used in quantitative ADC studies.

Spontaneous intracranial hypotension with pituitary adenoma.

Spontaneous intracranial hypotension (SIH) is an unusual syndrome that is characterised by positional headache, neck rigidity, nausea and vomiting. The characteristic magnetic resonance imaging (MRI) findings are diffuse smooth pachymeningeal thickening and enhancement, downward displacement of posterior fossa structures and pituitary gland enlargement. An unusual case of SIH with pituitary macro-adenoma and subsequent subdural haemorrhage is presented, and its clinical picture, MRI findings and possible pathophysiological mechanism are discussed.

Subacute sclerosing panencephalitis: relationship between clinical stage and diffusion-weighted imaging findings.

PURPOSE: To investigate the relationship between clinical stages and apparent diffusion coefficient (ADC) changes in the brain of patients with subacute sclerosing panencephalitis (SSPE). MATERIALS AND METHODS: A total of 18 patients with stage II (N = 11) and III (N = 7) SSPE and 11 age-matched controls underwent routine MRI and diffusion-weighted imaging (DWI). The ADC values were automatically calculated. Seven distinct neuroanatomic structures (frontal, parieto-occipital, and cerebellar white matter; deep white matter; thalamus; basal ganglia; and brainstem) were selected for analysis in the patient and control groups. RESULTS: Hyperintensities in the periventricular and subcortical white matters on T2-weighted images and ADC maps were detected in 63.6% of patients with stage II and in all patients with stage III. There were significant differences between stage II and III patients and also between patients and control group in ADC values that obtained from all locations. The highest mean ADC values were calculated in stage III patients. Although MRI and DWI findings were normal in four patients with stage II disease, ADC values were significantly increased when compared with controls. CONCLUSION: The stage of disorder may be independent of DWI appearance during the early stage (stages I and II), even though the brain is affected. Therefore, DWI and ADC values supplemental to routine MRI should also be utilized for lesion detection and definition to enhance diagnostic accuracy in patients with SSPE.