Radiologic-pathologic correlation of lesions in resected liver specimens with an ex vivo MRI-compatible localization device.

OBJECTIVE: Liver lesion characterization is limited by the lack of an established gold standard for precise correlation of radiologic characteristics with their histologic features. The objective of this study was to demonstrate the feasibility of using an ex vivo MRI-compatible sectioning device for radiologic-pathologic co-localization of lesions in resected liver specimens. METHODS: In this prospective feasibility study, adults undergoing curative partial hepatectomy from February 2018 to January 2019 were enrolled. Gadoxetic acid was administered intraoperatively prior to hepatic vascular inflow ligation. Liver specimens were stabilized in an MRI-compatible acrylic lesion localization device (27 × 14 × 14 cm3) featuring slicing channels and a silicone gel 3D matrix. High-resolution 3D T1-weighted fast spoiled gradient echo and 3D T2-weighted fast-spin-echo images were acquired using a single channel quadrature head coil. Radiologic lesion coordinates guided pathologic sectioning. A final histopathologic diagnosis was prepared for all lesions. The proportion of successfully co-localized lesions was determined. RESULTS: A total of 57 lesions were identified radiologically and sectioned in liver specimens from 10 participants with liver metastases (n = 8), primary biliary mucinous cystic neoplasm (n = 1), and hepatic adenomatosis (n = 1). Of these, 38 lesions (67%) were < 1 cm. Overall, 52/57 (91%) of radiologically identified lesions were identified pathologically using the device. Of these, 5 lesions (10%) were not initially identified on gross examination but were confirmed histologically using MRI-guided localization. One lesion was identified grossly but not on MRI. CONCLUSIONS: We successfully demonstrated the feasibility of a clinical method for image-guided co-localization and histological characterization of liver lesions using an ex vivo MRI-compatible sectioning device. KEY POINTS: • The ex vivo MRI-compatible sectioning device provides a reliable method for radiologic-pathologic correlation of small (< 1 cm) liver lesions in human liver specimens. • The sectioning method can be feasibly implemented within a clinical practice setting and used in future efforts to study liver lesion characterization. • Intraoperative administration of gadoxetic acid results in enhancement in ex vivo MRI images of liver specimens hours later with excellent image quality.

Endoleak after endovascular aneurysm repair: evaluation of a single-acquisition CTA protocol using a prebolus.

PURPOSE: To investigate a single-acquisition computed tomographic angiography (CTA) protocol using a prebolus injection technique to visualize the stent-graft lumen and endoleak after endovascular aneurysm repair (EVAR). METHODS: Of 162 EVAR patients referred for CTA over a 2-year period, 18 (15 men; mean age 66.4 years) with an endoleak met the study inclusion criteria, which included constant endoleak size and scans using 3 different CT protocols at least once during follow-up: monophasic CTA (C1), biphasic CTA (C2.1 and C2.2), and single-acquisition CTA using a prebolus (PB). All CTA examinations were performed with the same overall volume of contrast medium (120 mL) and were started manually using a bolus-tracking technique. Attenuation was measured within the aortic lumen proximal to the stent prosthesis (Ao) and within the endoleak itself (EL). RESULTS: Mean attenuation ranged between 200 (C2.2) and 313 HU (C2.1) within Ao and between 172 (C2.2) and 235 HU (C2.1) within the endoleak. The attenuation differences between Ao (C1) and Ao (PB), as well as between Ao (C2.1) and Ao (PB), were not statistically significant, while the attenuations of Ao (C2.2) and Ao (PB) differed significantly (p<0.001), with higher attenuation in PB. Compared to EL (PB), none of the mean EL attenuation values (C1, C2.1, and C2.2) differed significantly. CONCLUSION: This prebolus CTA protocol combines late-phase attenuation of a biphasic image acquisition protocol for endoleak visualization with high opacification of the stent lumen without exposing the patient to radiation twice.

Low-dose triple-rule-out using 320-row-detector volume MDCT--less contrast medium and lower radiation exposure.

OBJECTIVES: To investigate image quality of triple-rule-out (TRO) computed tomography (CT) using a 320-row-detector CT system with substantially reduced contrast medium volume at 100 kV. METHODS: Forty-six consecutive patients with noncritical, acute chest pain underwent 320-row-detector CT using a two-step TRO protocol consisting of a non-spiral, non-gated chest CT acquisition (150 mA) followed by a non-spiral, electrocardiography-gated cardiac acquisition (200-500 mA based on body mass index (BMI)). Data were acquired using a biphasic injection protocol with a total iodinated contrast medium volume of 60 ml (370 mg/ml). Vessel attenuation and effective doses were recorded. Image quality was scored independently by two readers. RESULTS: Mean attenuation was 584 ± 114 Hounsfield units (HU) in the ascending aorta, 335 ± 63HU in the aortic arch, 658 ± 136HU in the pulmonary trunk, and 521 ± 97HU and 549 ± 102HU in the right and left coronary artery, respectively. In all but one patient, attenuation and image quality allowed accurate visualization of the pulmonary arteries, thoracic aorta, and coronary arteries in a single examination. Ninety-six percent of all coronary artery segments were rated diagnostic. Radiation exposure ranged between 2.0 and 3.3 mSv. CONCLUSION: Using 320-row-detector CT the investigated low-dose TRO protocol resulted in excellent opacification and image quality with substantial reduction of contrast medium volume compared to recently published TRO protocols.

Maternofetal pharmacokinetics of a gadolinium chelate contrast agent in mice.

PURPOSE: To determine the maternofetal pharmacokinetics of gadoterate meglumine in mice during the first 48 hours following maternal intravenous injection of a high dose of 0.5 mmol of gadolinium per kilogram. MATERIALS AND METHODS: All the studies complied with French law and the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. Balb/C mice (n = 23) at 16 days of gestation were examined for 48 hours after maternal intravenous administration of 0.5 mmol gadolinium per kilogram of gadoterate meglumine. Gadolinium concentration in the placentas, fetuses, and amniotic fluid was determined by using mass spectrometry, and the total placental and fetal gadolinium content was calculated. Gadoterate meglumine half-life in the different compartments was estimated with one- and two-compartment models. Kruskal-Wallis and Wilcoxon signed-rank tests were used to compare the pharmacokinetic profiles. RESULTS: Gadoterate meglumine passed the placental barrier, entering the fetuses and amniotic fluid before being redistributed back to the mother. The placental gadolinium concentration showed two-compartmental decay, with a first half-life of distribution of 47 minutes and a second half-life of elimination of 107 hours. The half-lives in the fetuses and amniotic fluid were, respectively, 4 and 5 hours and followed a monocompartmental model after the initial peak. The maximal gadolinium fetal concentration (31.8 nmol/g) was observed 30 minutes after injection, which corresponded to a total fetal content of 0.077% of the injected dose. CONCLUSION: In mice, gadoterate meglumine, an extracellular nonspecific gadolinium chelate contrast medium, passed the placenta before being redistributed back to the mother, resulting in undetectable fetal concentrations after 48 hours.

Radiographic staging of ossification of the medial clavicular epiphysis.

Determination of the stage of ossification of the medial clavicular epiphysis is a crucial part of forensic age estimation when evaluating living subjects over 18 years of age. In the present study, we comparatively assessed conventional radiographs and computed tomography (CT) scans of sternoclavicular joints used to perform forensic age assessments in 57 individuals undergoing criminal proceedings. With CT, it was possible to determine the ossification stage of all clavicles studied. In the case of conventional radiography, reliable assessment of ossification stage was not possible in 15 out of 114 clavicles studied due to the superimposition of other structures. Regarding agreement between the methods, both radiography and CT produced identical staging results in 97 out of 99 clavicular epiphyses. In two cases, however, ossification was classified as stage 2 by CT and as stage 3 by conventional radiography. Regarding stages 4 and 5, both methods produced identical staging results in all cases. In forensic age estimation practice, it is necessary that conventional radiographic reference studies be used for ossification stage classification by conventional radiography and that CT reference studies be used for ossification stage classification by CT. Further studies in dead bodies of known age are required to issue a recommendation as to whether conventional radiography using obtained in three planes or CT is the method of choice for the assessment of clavicular ossification.

Magnetic resonance imaging of the clavicular ossification.

Assessment of the degree of ossification of the medial clavicular epiphyseal cartilage is of vital importance in forensic age diagnostics of living individuals aged more than 18 years. To date, reference studies on the assessment of clavicular ossification using imaging procedures only relate to conventional radiography and computed tomography (CT). In this study, magnetic resonance (MR) scans of 54 sternoclavicular joints of bodies aged between 6 and 40 years were evaluated prospectively. All of the examined medial clavicular epiphyseal cartilages permitted an assessment of the degree of ossification. Stage 2 was first observed at the age of 15.0 years, the earliest age at which stage 3 was observed was 16.9 years, and stage 4 was first observed at the age of 23.8 years. The observed age intervals of the respective degrees of ossification correspond to the known data from X-ray and CT scan examinations. The achieved results should be examined with a larger number of cases. A modified examination protocol is required for the MR examination of the medial clavicular epiphyseal cartilage for the purpose of forensic age diagnostics of living individuals.

Value of fetal cerebral MRI in sonographically proven cardiac rhabdomyoma.

BACKGROUND: Tuberous sclerosis complex (TSC) is an autosomal dominant phakomatosis associated with intracardiac rhabdomyomas. OBJECTIVE: The aim of our study was to examine the value of cerebral MRI in diagnosing TSC in fetuses with intracardiac rhabdomyomas, applying the TSC Consensus Conference (TSCCC) criteria. MATERIALS AND METHODS: In a prospective manner six consecutive fetuses with cardiac rhabdomyomas (21-34 weeks' gestation) underwent cerebral MRI. The MRI results were correlated with clinical follow-up at 10-34 months after birth, histology, and genetic data. RESULTS: In five of the six fetuses the diagnosis of TSC was established. In two of five fetuses MRI demonstrated cerebral manifestations of TSC that correlated well with severe epilepsy manifesting during the follow-up period. In another two of five fetuses MRI as well as clinical follow-up were normal. One of five pregnancies was terminated and histology demonstrated microscopically small subependymal nodules not demonstrated by MRI. CONCLUSION: The results of our study agree with the available literature that fetal MRI is sufficient for the detection of cerebral lesions in TSC and should be better promoted. The TSCCC criteria can also be applied to fetal MRI.

Fetal MRI demonstrates glioependymal cyst in a case of sonographic unilateral ventriculomegaly.

We report a fetus of 28 weeks' gestation in which ultrasonography demonstrated unilateral ventriculomegaly and microcephaly. Fetal MRI demonstrated a simple, left paramedian occipital cyst with rarefaction of the corpus callosum and thinning of the adjacent cortical mantle. Ischaemia was suggested as the underlying pathogenesis, but autopsy after termination of pregnancy revealed a glioependymal cyst. This case highlights consideration of the rare diagnosis of glioependymal cyst when a cystic lesion associated with cerebral malformations, particularly dysgenesis of the corpus callosum, is demonstrated and fetal MRI suggests an ischaemic origin.

Improved diagnosis of early kidney allograft dysfunction by ultrasound with echo enhancer--a new method for the diagnosis of renal perfusion.

BACKGROUND: Conventional ultrasound parameters such as the resistance index (RI) are only of limited use in the diagnosis of early allograft dysfunction. We, therefore, performed a prospective study to compare the value of ultrasound contrast media (USCM) with conventional US in the diagnosis of early allograft dysfunction. METHODS: A total of 48 consecutive kidney recipients underwent US examination after USCM administration 4-10 days after transplantation. Arterial inflow was determined in the interlobar artery and renal cortex using time-intensity curve (TIC) software. The difference in time-to-peak intensity between these two vascular territories was determined, and a perfusion quotient (PQ) was defined as the ratio of TIC increase of interlobar artery to renal cortex. Three patients with segmental loss of renal perfusion demonstrated by Doppler US were excluded. RESULTS: Nineteen patients had an uneventful clinical course (control group); PQ was 1.2 +/- 0.4. Seven patients with a large perirenal haematoma, without rejection had an increased PQ (P < 0.05) and a prolonged time difference (P < 0.05). Based on clinical and histological criteria, the remaining patients were classified as acute tubular necrosis (ATN) (n = 7), non-vascular rejection (n = 7) or vascular rejection (n = 5). RI determination could not discriminate these groups. Patients with ATN (PQ = 1.6 +/- 0.7) or non-vascular rejection (PQ = 1.1 +/- 0.6) had a lower PQ than patients with vascular rejection (PQ = 2.2 +/- 0.8, P < 0.05). The time difference in all three subgroups was longer compared with controls. CONCLUSIONS: USCM might be superior in the diagnosis of early kidney allograft dysfunction compared with conventional US by means of RI determination. Perirenal haematoma, ATN and vascular rejection are associated with characteristic changes of the TIC.

The influence of slice thickness on assessment of clavicle ossification in forensic age diagnostics.

Computed tomography scans originally obtained to assess the ossification status of the medial clavicular epiphyses of 40 live subjects for forensic age estimation purposes were analysed. From the data acquired we reconstructed images with slice thicknesses of 1, 3, 5 and 7 mm, and based on the classification of stages by Schmeling et al. (Int J Legal Med 118:5-8, 2004), we determined the ossification stage for each reconstructed slice thickness, separately for both sides. Of the 80 clavicular epiphysial plates examined, seven displayed slice-thickness-dependent differences at certain ossification stages. In one case a slice thickness of 1 mm led to a different diagnosis of the ossification stage than a slice thickness of 3 mm, in three cases the diagnoses differed between the slice thicknesses of 3 and of 5 mm, and in another three cases, between 5 and 7 mm. We therefore conclude that for age estimation purposes, the slice thickness should be 1 mm to ensure maximum accuracy and diagnostic reliability.

Studies on the time frame for ossification of the medial epiphysis of the clavicle as revealed by CT scans.

The authors retrospectively analyzed 629 CT images of patients aged between 15 and 30 years produced during multiple trauma diagnostics at the Unfallkrankenhaus Berlin. For the purposes of this study, the authors reliably determined the ossification status of the medial epiphysis of the clavicle in 556 cases, using the classification of stages by Schmeling et al. In both sexes, stage 2 was first noted at age 15. In male patients, the earliest occurrence of stage 3 was noted at age 17, in female patients at age 16. Stage 4 was first achieved by both sexes at age 21. Stage 5 was first noted in female patients at age 21 and in male patients at age 22, which is 4 or 5 years earlier than was observed by a comparable study using conventional radiographs. The partial-volume effect in computed tomography using the thick slice scanning mode was discussed as a possible explanation for this early visualization. The question of how slice thickness affects the age intervals between ossification stages identified by CT examinations should be examined in additional studies.

The use of contrast-enhanced US in renal transplant: first results and potential clinical benefit.

INTRODUCTION AND PURPOSE: Little use has been made so far of the intrinsic advantages of ultrasound (US) for quantifying tissue perfusion of parenchymal organs, that is, its high spatial and temporal resolution and immediate availability in any clinical situation. Since acute rejection of a kidney graft primarily involves the sub-capsular capillaries, early and detailed evaluation of blood flow in this area is highly desirable. Using a clinically established US contrast medium (USCM) of the second generation and improved US technology, we performed a study to investigate whether it is possible to adequately diagnose rejection after kidney transplant by evaluating the arterial inflow of an echo enhancer. PATIENTS AND METHODS: A total of 32 patients underwent US examination with an echo enhancer (1.6 ml SonoVue, Bracco-Altana) 5 to 7 days after kidney transplantation. The examinations were performed using the Aplio US system (Toshiba) with a 3.5-MHz transducer and micro flow imaging (MI 0.1). Contrast medium inflow was determined in the renal artery and the renal cortex using Windows-based, time-intensity curve (TIC) software. The temporal difference in contrast medium inflow between the two vascular territories was determined (Dt = time baseline renal cortex--time baseline renal artery). Patients with primary graft failure (no function until day 3) were excluded (number of patients, n=2). In patients with large peri-renal hematoma (n=6), the effect of US on perfusion was determined and the results in these cases (hematoma group) were compared with those in the remaining patients. RESULTS: Seventeen patients had uneventful clinical course (resistance index (RI) on day 7: 0.75+/-0.11). In this group US demonstrated a uniform inflow of the CM. The calculated slopes were comparable with those of the interlobar artery and renal cortex (no rejection group). Seven patients showed histologically confirmed acute rejection on days 5 to 7 after transplantation (rejection group). The RI in this group was at the upper limit on day 7 (0.77+/-0.08). The temporal difference in CM arrival between the two vascular territories was greater in the rejection group (2.27+/-0.73 s) compared with the normal group (0.97+/-0.62 s, p<0.05, p=significance). The difference was also increased in the hematoma group (1.5+/-1.3 s, p>0.05). The size of the hematoma correlated with the extent to which USCM inflow was altered. In only two cases, the USCM examination demonstrated a perfusion defect. CONCLUSIONS: The use of echo enhancers has potential to diagnose acute kidney graft rejection in its early stages. US not only identifies kidney perfusion defects but also provides information on the effect of a large peri-renal hematoma.

Truncus arteriosus communis in a midtrimester fetus: comparison of prenatal ultrasound and MRI with postmortem MRI and autopsy.

Different techniques are used in fetal cardiology, and their accuracy has been demonstrated on several occasions. Color Doppler US has proved to be a reliable and valuable tool in the diagnosis of fetal cardiac abnormalities. Magnetic resonance imaging (MRI) of the fetal heart has, so far, played no role in prenatal diagnostics. We report on a truncus arteriosus communis diagnosed prenatally during a screening ultrasound at 22 weeks of gestation. In addition to real-time ultrasound and color Doppler echocardiography, fetal MRI was performed. Fetal echocardiography arose suspicion of a type I common trunk. Fetal MR showed solely a widened vessel coursing retrocardially and additionally an inhomogeneous fluid distribution of the lung not shown on prenatal US. After termination of pregnancy at 23 weeks of gestation, MR fetography and autopsy were performed, and both found a type II common trunk. MR autopsy of the heart was very reliable in this case and could be an alternative when fetal pathology is not available for different reasons. Postmortem MRI was also able to demonstrate the inhomogeneous fluid distribution in the lung, which was confirmed by autopsy. Fetal and postmortem MR was reliable in the detection of an inhomogeneous fluid distribution in the lung not shown on prenatal US, providing a relevant additional finding to US. Therefore, MRI should be used more often in fetal cardiology, although it still must be further developed.

Studies on the time frame for ossification of the medial clavicular epiphyseal cartilage in conventional radiography.

Radiological assessment of the degree of ossification of the medial clavicular epiphyseal cartilage plays a vital part in forensic age diagnosis of living adolescents and young adults. A total of 873 plain chest radiographs requested by the staff medical officer for members of staff aged 16-30 at the University Hospital Charité were evaluated retrospectively. Of these X-rays 699 permitted an assessment of ossification of at least 1 side of the clavicle. In addition to the customary stages (1: non-ossified epiphysis, 2: discernible ossification centre, 3: partial fusion, 4: total fusion) a stage 5 was also defined, characterised by the disappearance of the epiphyseal scar following total fusion. The earliest age at which stage 3 was detected in either gender was 16 years. Stage 4 was first observed in women at 20 years and in men at 21 years. In both genders, the earliest observation of stage 5 was at 26 years. It was concluded that plain chest radiographs can essentially be used to assess clavicular ossification. In practice, if overlap in posterior-anterior views impedes evaluation, a lateral view should also be taken to facilitate age estimation. In forensic practice the reference values of the present paper should be applied.

MRI of cardiac rhabdomyoma in the fetus.

Primary cardiac tumors are rarely diagnosed in utero and are usually seen on prenatal echocardiography. Cardiac rhabdomyomata can be associated with tuberous sclerosis. Prenatal MRI can be performed to assess associated malformations. This case report illustrates the ability of fetal MRI to image cardiac rhabdomyata and compares it with prenatal and postnatal echocardiography.