Hibernoma: MRI appearance of a rare tumor

We report the features of a hibernoma on magnetic resonance (MR) imaging. The MR characteristics of this lesion were consistent with a complex lipid-containing mass. The mass did not suppress on short tau inversion recovery (STIR) imaging and was clearly not a simple lipoma. Hibernoma should be considered in the differential diagnosis of complex fatty masses.     

MRI appearance of placenta percreta and placenta accreta.

The purpose of this paper is to describe the magnetic resonance imaging (MR) features of placenta accreta and percreta. We retrospectively reviewed MRI findings in four cases of placenta accreta/percreta to determine features which assist in identifying the presence and extent of placental implantation abnormality. All patients had ultrasound (US) examinations. Pathologic correlation was available in all cases. There were two cases of placenta percreta and two cases of placenta accreta. All cases were treated by hysterectomy. In the two cases of placenta percreta, the placenta demonstrated transmural extension through the uterus (percreta) on MRI. In the two cases of placenta accreta, the location of thinning in the uterine wall correlated with the location of placental invagination into the myometrium at pathology. US correlation was available in all four cases. Gray scale US did not demonstrate placental invasion in any of the four cases of placenta accreta/percreta, however, in two of three cases in which color Doppler was performed, there was flow at the uterine margin suspicious for implantation abnormality. In conclusion, MRI is useful for identifying the presence and extent of placenta accreta/percreta.     

MRI appearance of disseminated osseous tuberculosis

Disseminated osseous tuberculosis is a rare disease. This is a report of two cases of disseminated osseous tuberculosis imaged with MRI at 1.5-T, CT, plain radiography and bone scintigraphy. CT and plain radiography demonstrated either highly destructive or cystic lesions with sclerotic margins. Bone scintigraphy and plain radiography were quite insensitive in detecting areas of involvement compared to MRI. On MRI the abnormal areas had short T-1 relaxation values, which is an atypical appearance for bony infections, and prolonged T-2 relaxation values. The reason for the T-1 relaxation behavior is uncertain. MRI also provided delineation of epidural extent.     

MRI of liver tumors using gadolinium-DOTA: prospective study comparing spin-echo long TR-te sequence and CT

Thirty-nine patients with liver tumors were examined using MRI at 0.5 T before and after intravenous bolus injection of either 0.1 mmol/kg (n = 18) or 0.2 mmol/kg (n = 21) of Gadolinium-Dota, using spin-echo T1-and T2-weighted sequences before injections and spin-echo or gradient-echo sequences after injection. When contrast-to-noise (C/N) data were normalized relative to time, optimal mean C/N was observed after gadolinium injection. However, subjective study and case-by-case C/N measurement showed better contrast for SE 2000/60 and CT with injection in 62% and 42% of cases, respectively.     

MRI appearance of the pelvis in the post cesarean-section patient

Fever in the post-cesarean section patient may indicate the presence of a potentially life-threatening complication, including abscess, ovarian vein thrombosis, and uterine dehiscence. Imaging findings are often utilized to ascertain the presence or absence of such complications. Familiarity with the normal findings in the post-operative period is essential in making this determination. The purpose of this investigation is to describe the MRI appearance of the post-cesarean section pelvis. Over a 67-month period, 50 patients with persistent low-grade fevers following c-section were referred for MR imaging. Imaging was performed 3-10 days post-operatively. Axial T1-weighted and T2-weighted images were acquired in addition to sagittal T2-weighted images. Coronal images were obtained in some cases. Clinical correlation was obtained through the patients charts, confirming discharge of the patients in stable condition. The uterine incision site usually demonstrated findings consistent with subacute hematoma. The anterior uterine myometrium demonstrated enlargement relative to the posterior uterine wall. Bladder flap hematomas were seen in 64% of cases. Three cases (6%) demonstrated parametrial edema and none of these patients demonstrated ovarian vein thrombosis. Two cases of pelvic hematoma were noted. The normal post-c-section incision site may demonstrate increased or decreased signal intensity on T2-weighted images and intact endometrial and serosal layers mitigate against the diagnosis of incisional dehiscence. Bladder flap hematomas occurred in slightly more than half the cases. Parametrial edema and pelvic hematoma can be seen as post-surgical changes.     

Gadolinium-DTPA-enhanced MRI of intraocular tumors

The value of gadolinium-enhanced MRI in 30 patients with intraocular lesions has been evaluated. Seventeen patients had a uveal melanoma, two a ciliary body melanoma, three had uveal metastases, one lymphoma, four had senile macula degenerations, and three uveal nevi. Twelve of 17 patients with melanoma were followed up by MRI after ruthenium plaque therapy on 2–4 occasions. Melanomas showed high precontrast signal intensities and only a slight enhancement after intravenous Gd-DTPA was given. After ruthenium plaque therapy precontrast signal intensities (SI) decreased while a moderate signal increase on postcontrast scans was noted. Scars or tumor residues were better delineated on enhanced images. All other tumors than melanotic melanomas showed low SI on precontrast scans and a high signal increase after Gd-DTPA administration. Small amelanotic tumors were better delineated on postcontrast scans. In addition Gd-DTPA-enhanced MRI allowed differentiation between tumor and hemorrhage. No signal increase after Gd-DTPA application was seen in subretinal or vitreous hemorrhages of varying ages.     

MRI appearance of cervical incompetence in a pregnant patient

Ultrasonography is currently the principal imaging modality for diagnosing cervical incompetence during pregnancy. Various technical factors, both patient and technologist/transducer related, may limit its evaluation for cervical incompetence. MRI is not dependent on these technical considerations. MRI may demonstrate a higher degree of soft tissue contrast than ultrasonography for depicting uterine anatomy. MRI may, in some instances, be more accurate in depicting cervical incompetence in the gravid patient. We present the first case of cervical incompetence in a pregnant patient diagnosed by MRI, in which ultrasonography failed to provide conclusive evidence of extra-uterine herniation of the amniotic sac.     

Tissue characterization of benign brain tumors: use of NMR-tissue parameters

To evaluate the potentials of NMR tissue parameters for tissue characterization we investigated 68 patients with benign brain tumors. Tissue parameters were accurately measured by a recently developed interlaced triple sequence. Each individual tumor was characterized by a set of three numbers (relaxation times T1 and T2 and proton density Rho). Different tumors exhibited significant overlaps of the three tissue parameters. Therefore a reliable prediction of the histological diagnosis based on the quantitative analysis of tissue parameters alone was not possible. T2-prolongation correlated well with water content and "regressive changes" in meningiomas and neuromas.     

MRI of aggressive fibromatosis: frequent appearance of high signal intensity on T2-weighted images

Magnetic resonance imaging of seven patients with eight pathologically proven desmoid tumor tumors was performed and retrospectively reviewed. On T2-weighted images, all but one lesion demonstrated increased signal intensity relative to muscle, and had signal intensity similar to that of fat. The signal was heterogenous in six of these seven lesions. In a patient with synchronous multicentric lesions, light microscopy correlation revealed increased cellularity in one lesion with increased signal intensity and dense collagenous elements in a second lesion, with decreased signal intensity. High signal intensity appears to be typical but nonspecific, and in following these patients could indicate recurrent tumor, superimposed inflammatory process or granulation tissue.     

Magnetohydrodynamic thermochemotherapy and MRI of mouse tumors

A dextran-ferrite magnetic fluid was successfully tested as magnetic resonance imaging (MRI) contrast agent. The same magnetic fluid was then combined with Melphalan, a chemotherapeutic drug, and used for magnetohydrodynamic thermochemotherapy of different tumors. The placement of the tumors in an AC magnetic field led to hyperthermia at 46 °C for 30 min. In combination with tumor slime aspiration, a 30% regression of ∼130 mm³ non-metastatic P388 tumors in BDF₁ mice was reached, together with a life span increase of 290%. The same procedure associated with cyclophosphamide treatment of ∼500 mm³ metastases tumor increased the animal's life span by 180%.     

Focal nodular hyperplasia of the liver: diffusion and perfusion MRI characteristics

Purpose

To present diffusion and perfusion magnetic resonance imaging (MRI) characteristics of focal nodular hyperplasia (FNH) of the liver.

Materials and Methods

Thirty-five patients with 52 FNHs (21 were pathologically-confirmed) underwent MRI at 1.5-T device. MR diffusion [diffusion-weighted imaging (DWI)] was performed using a free-breathing single-shot, spin-echo, echo-planar sequence with b gradient factor value of 500 s/mm². MR perfusion [perfusion-weighted imaging (PWI)] consisted of a 3D free-breathing LAVA sequence repeated up to 5 minutes after injection of 7 mL Gd-BOPTA (MultiHance, Bracco, Italy) and 20 mL saline flush at a flow rate of 4 mL/s. Apparent diffusion coefficient (ADC) and time-signal intensity curve (TSIC) were obtained for both normal liver and each FNH by two reviewers in conference; maximum enhancement (ME) percentage, time to peak enhancement (TTP), and maximal slope (MS) were also calculated.

Results

On DWI mean ADC value was 1.624×10^− 3 mm²/s for normal liver and 1.629×10^− 3 mm²/s for FNH. ADC value for each FNH and the normal liver was not statistically different (P= .936). On PWI, TSIC-Type 1 (quick and marked enhancement and quick decay followed by slowly decaying) was observed in all 52 FNHs, and TSIC-Type 2 (fast enhancement followed by slowly decaying plateau) in all normal livers. The mean ME, TTP and MS values were significantly different for FNH and normal liver (P= .005).

Conclusion

FNHs of the liver showed typical diffusion and perfusion MRI characteristics in all cases. On the ADC map, we could get similar value between the FNHs and the background parenchyma. On the perfusion imaging, FNHs showed a different pattern distinguished from the background liver.     

Early contrast enhancement of the liver: exact description of subphases using MRI

Purpose

The purpose of this study was to describe the subphases of early post-contrast enhancement of the liver, using vessel enhancement patterns, and correlate these findings with enhancement patterns of abdominal organs.

Materials and Methods

A total of 114 patients who underwent gadolinium-enhanced abdominal magnetic resonance imaging examinations constituted the final study group, of which 56 were women (age range, 3–94 years; mean, 50 years) and 58 were men (age range, 6–85 years; mean, 54 years). Early post-contrast sequences in all patients were evaluated retrospectively by two reviewers for the determination of the presence of contrast enhancement in predetermined major vessels of the abdomen and qualitative and quantitative extent of enhancement of the renal cortex, spleen, pancreas and liver. Based on the overall findings, subphases of early contrast enhancement of the liver were described and quantitative extent of enhancement of organs was correlated with subphases of early contrast enhancement of the liver. Mann–Whitney U test and one-way unbalanced analysis of variance tests were used for the comparisons.

Results

Early hepatic arterial phase was observed in 14/114 patients, mid-hepatic arterial phase in 23/114 patients, late hepatic arterial phase in 33/114 patients, splenic vein only hepatic arterial dominant phase in 20/114 patients and hepatic arterial dominant phase in 24/114 patients. There was an overall association between the subphases of enhancement and the quantitative extent of enhancement for all studied organs (P<.0001).

Conclusion

The evaluation of vessel and organ enhancement patterns has allowed the characterization of five different subphases in early post-contrast enhancement of the liver. The quantitative extent of enhancement of abdominal organs also demonstrated significant correlation with these five subphases.     

MRI, CT, and plain film appearance of anterior spina bifida

Anterior spina bifida or butterfly vertebral body has a well known and characteristic appearance on plain film and CT. Its appearance on magnetic resonance imaging also appears to be characteristic and should not be mistaken for more serious abnormalities.     

Histopathologically confirmed focal nodular hyperplasia of the liver: Gadoxetic acid-enhanced MRI characteristics

Purpose

The purpose of this study was to evaluate enhancement characteristics of histopathologically confirmed focal nodular hyperplasia (FNHs) with gadoxetic acid-enhanced MRI.

Materials and Methods

Twenty-seven patients with all histopathologically proven FNHs were retrospectively identified. MRI consisted of T₁- and T₂-weighted (w) sequences with and without fat saturation (FS), multiphase dynamic T₁-w images, and FS T₁-w images during the hepatobiliary phase. Standard of reference was surgical resection (n = 24) or biopsy (n = 3). Images were analyzed for morphology and contrast behavior including signal intensity (SI) measurement on T₁-w images normalized to the pre-contrast base line.

Results

In total 36 FNHs were evaluated. All FNHs showed enhancement in the arterial phase, significant reduction contrast enhancement (“wash-out”) in the late dynamic phases was not present. In the hepatobiliary phase, all FNHs (100%) showed enhancement (overall SI increase, 118% (± 91%), P < 0.001) with at least partial hyperintensity to the liver. Upon visual comparison, 3 of 36 FNHs appeared with heterogeneous/partial enhancement (8%) and 7 (19%) showed rim-accentuated enhancement.

Conclusion

The typical enhancement pattern of FNH with gadoxetic acid consists of arterial hyperperfusion, no wash-out during the venous phase, and at least partial hyperintensity compared to the liver in the hepatobiliary phase. Partial hypointensity or rim-accentuated enhancement rarely occurs.     

Small animal MRI at 0.35 Tesla: growth and morphology of intra-organ murine tumors

A whole-body small animal radiofrequency coil was designed and built for use with a 0.35 Tesla clinical magnetic resonance imager. The primary motivation for this work was to evaluate the effectiveness of this system for small animal magnetic resonance imaging of tumor-bearing mice. This noninvasive technique is shown to provide high resolution whole-body images of mice, to be capable of detecting intra-organ tumors, and to be useful for evaluating tumor size and growth. Its potential for monitoring response to experimental therapeutic regimens is also noted. Two tumor models were examined--colon adenocarcinoma MCA-38 and human ASPC-1 pancreatic adenocarcinoma.     

Granulomatous hepatitis: MRI findings.

The purpose of this study was to describe the magnetic resonance imaging findings of granulomatous hepatitis on T1-weighted, T2-weighted and postgadolinium images. Eight patients with histopathological diagnosis of granulomatous hepatitis were evaluated in this study. MRI examinations included precontrast T1-weighted breath-hold spoiled gradient echo, breathing independent STIR sequences, and T1-weighted breath-hold spoiled gradient-echo sequence following after i.v. gadolinium administration in arterial, intermediate and late phases. Diffuse nodular liver involvement was visualized in all patients. Nodules were consistent with granulomas and were 0.5-4.5 cm in diameter. Caseating granulomas were intermediate and high signal on T2-weighted, low signal on T1-weighted images. They revealed no enhancement in two patients, and enhanced in one patient. Noncaseating granulomas revealed intermediate signal on T1, and T2-weighted images and increased enhancement on arterial phase images with persisting enhancement in late phase images. Portal lymph nodes were visible in five patients. Splenomegaly was present in five patients. Granulomatous hepatitis has spectrum of MRI features, to be considered in differential diagnosis with other diffuse nodular liver pathologies.     

MRI texture analysis on texture test objects, normal brain and intracranial tumors

Texture analysis was performed in three different MRI units on T1 and T2-weighted MR images from 10 healthy volunteers and 63 patients with histologically confirmed intracranial tumors. The goal of this study was a multicenter evaluation of the usefulness of this quantitative approach for the characterization of healthy and pathologic human brain tissues (white matter, gray matter, cerebrospinal fluid, tumors and edema). Each selected brain region of interest was characterized with both its mean gray level values and several texture parameters. Multivariate statistical analyses were then applied in order to discriminate each brain tissue type represented by its own set of texture parameters. Texture analysis was previously performed on test objects to evaluate the method dependence on acquisition parameters and consequently the interest of a multicenter evaluation. Even obtained on different sites with their own acquisition routine protocol, MR brain images contain textural features that can reveal discriminant factors for tissue classification and image segmentation. It can also offer additional information in case of undetermined diagnosis or to develop a more accurate tumor grading.     

Distinguishing hepatic hemangiomas from metastatic tumors using T1 mapping on gadoxetic-acid-enhanced MRI

Objective

The objective was to evaluate the usefulness of T1 mapping in distinguishing hepatic hemangiomas from metastatic tumors on gadoxetic-acid-enhanced magnetic resonance imaging.

Methods

We examined 20 hemangiomas in 14 patients and 21 metastatic tumors in 11 patients. We performed T1 mapping using the double-flip angle method before and after the injection of gadoxetic acid. Quantitative evaluation was carried out using the pre- and post-contrast enhancement ratios (CERs), and qualitative evaluation was conducted to evaluate the added value of T1 mapping using receiver operating characteristics analysis.

Results

The mean CERs of metastatic tumors at 70 s, 240 s and 20 min after the injection of gadoxetic acid were 1.54 (95% confidence interval: 1.37–1.71), 1.47 (1.34–1.6) and 1.30 (1.19–1.41); those of hemangiomas were 3.36 (2.41–4.31), 3.06 (2.44–3.68) and 2.20 (2.02–2.38), respectively. The mean CERs of hemangiomas were significantly higher than those of metastatic tumors (P< .05). When the mean CER cutoff value 20 min after the injection was set at 1.6, the diagnostic sensitivity of hepatic hemangiomas was 100%. There was no added value observed statistically in the qualitative evaluation of T1 mapping (P> .05).

Conclusion

It is valuable to evaluate quantitatively T1 mapping 20 min after hepatobiliary phase acquisition in the case of difficulty in distinguishing hepatic hemangiomas from metastatic tumors qualitatively.