Ashkan Heshmatzadeh Behzadi

Immediate Allergic Reactions to Gadolinium-based Contrast Agents: A Systematic Review and Meta-Analysis

Purpose To perform a systematic review and meta-analysis to determine if there are differences in rates of immediate allergic events between classes of gadolinium-based contrast agents (GBCAs). Materials and Methods PubMed and Google Scholar databases were searched for studies in which rates of immediate adverse events to GBCAs were reported. The American College of Radiology classification system was used to characterize allergic-like events as mild, moderate, or severe, and the total number of administrations of each GBCA was recorded. Where necessary, authors of studies were contacted to clarify data and eliminate physiologic reactions. Relative risks of GBCA types were estimated by using the Mantel-Haenszel type method. Results Nine studies in which immediate reactions to GBCA were recorded from a total of 716 978 administrations of GBCA met the criteria for inclusion and exclusion. The overall rate of patients who had immediate allergic-like reactions was 9.2 per 10 000 administrations and the overall rate of severe immediate allergic-like reactions was 0.52 per 10 000 administrations.. The nonionic linear chelate gadodiamide had the lowest rate of reactions, at 1.5 (95% confidence interval [CI]: 0.74, 2.4) per 10 000 administrations, which was significantly less than that of linear ionic GBCAs at 8.3 (95% CI: 7.5, 9.2) per 10 000 administrations (relative risk, 0.19 [95% CI: 0.099, 0.36]; P < .00001) and less than that for nonionic macrocyclic GBCAs at 16 (95% CI: 14, 19) per 10 000 administrations (relative risk, 0.12 [95% CI: 0.05, 0.31]; P < .001). GBCAs known to be associated with protein binding had a higher rate of reactions, at 17 (95% CI: 15, 20) per 10 000 administrations compared with the same chelate classification without protein binding, at 5.2 (95% CI: 4.5, 6.0) per 10 000 administrations (relative risk, 3.1 [95% CI: 2.4, 3.8]; P < .0001). Conclusion These data show the lowest rate of immediate allergic adverse events with use of the nonionic linear GBCA gadodiamide in comparison with those of ionic linear or nonionic macrocyclic GBCAs. A higher rate of immediate allergic adverse events was associated with ionicity, protein binding, and macrocyclic structure.

Comparison of MRI segmentation techniques for measuring liver cyst volumes in autosomal dominant polycystic kidney disease

Purpose: To compare segmentation methods for measuring liver cyst volumes in ADPKD. Methods: Liver cyst volumes in 42 ADPKD patients were measured using region growing, thresholding and cyst diameter techniques. Manual segmentation was the reference standard. ACCEPTED MANUSCRIPTPURPOSE To compare MRI segmentation methods for measuring liver cyst volumes in autosomal dominant polycystic kidney disease (ADPKD). METHODS Liver cyst volumes in 42 ADPKD patients were measured using region growing, thresholding and cyst diameter techniques. Manual segmentation was the reference standard. RESULTS Root mean square deviation was 113, 155, and 500 for cyst diameter, thresholding and region growing respectively. Thresholding error for cyst volumes below 500ml was 550% vs 17% for cyst volumes above 500ml (p<0.001). CONCLUSION For measuring volume of a small number of cysts, cyst diameter and manual segmentation methods are recommended. For severe disease with numerous, large hepatic cysts, thresholding is an acceptable alternative.

Preventing Allergic Reactions to Gadolinium-Based Contrast Agents.

Abstract Although the low incidence of immediate-type gadolinium-based contrast agent (GBCA) allergic reactions is widely known, preventing these reactions and properly managing them to reduce their adverse sequel can improve the already exceedingly favorable GBCA safety profile. This review article should help those who order, supervise, or administer GBCA contrast agents, including recognizing and handling allergic reaction risks intrinsic to their use. Areas of focus include factors indicating increased allergic reaction risk, patient selection strategies, skin testing, premedication, and treatment of adverse events.

Dentate Nucleus Signal Intensity Decrease on T1-weighted MR Images after Switching from Gadopentate Dimeglumine to Gadobutrol

Purpose To determine if the increased dentate nucleus signal intensity following six or more doses of a linear gadolinium-based contrast agent (GBCA) (gadopentetate dimeglumine) changes at follow-up examinations performed with a macrocyclic GBCA (gadobutrol). Materials and Methods This retrospective study included 13 patients with increased dentate nucleus signal intensity following at least six (range, 6-18) gadopentetate dimeglumine administrations who then underwent at least 12 months of follow-up imaging with multiple (range, 3-29) gadobutrol-enhanced magnetic resonance (MR) examinations. Dentate nucleus-to-pons and dentate nucleus-to-cerebellar peduncle signal intensity ratios were measured by two radiologists blinded to all patient information, and changes were analyzed by using the paired t test and linear regression. Results The mean dentate nucleus-to-pons and dentate nucleus-to-cerebellar peduncle signal intensity ratios increased after gadopentetate dimeglumine administration, from 0.98 ± 0.03 to 1.10 ± 0.03 (P < .0001) and from 0.98 ± 0.030 to 1.09 ± 0.02 (P < .0001), respectively. With gadobutrol, the mean dentate nucleus-to-pons and dentate nucleus-to-cerebellar peduncle signal intensity ratios decreased to 1.03 ± 0.03 and 1.02 ± 0.04, respectively (P < .0001). With use of a mixed effects model linear regression allowing for each patient to have a different y intercept, mean dentate nucleus-to-pons and dentate nucleus-to-cerebellar peduncle signal intensity ratios decreased with follow-up time (dentate nucleus-to-pons: slope = -0.2% per month [95% confidence interval: -0.0024, -0.0015], R2 = 0.58, P < .0001 for nonzero slope; dentate nucleus-to-cerebellar peduncle: slope = -0.2% per month [95% confidence interval: -0.0024, -0.0015], R2 = 0.61, P < .0001 for nonzero slope). Conclusion Dentate signal intensity increased with at least six gadopentetate dimeglumine-enhanced MR examinations and decreased after switching from a linear (gadopentetate dimeglumine) to a macrocyclic (gadobutrol) GBCA.

Complex liver cysts in Autosomal Dominant Polycystic Kidney Disease

PURPOSE To determine prevalence of complex liver cysts in Autosomal Dominant Polycystic Kidney Disease (ADPKD). METHODS Abdominal MRI in 186 ADPKD subjects were evaluated by two independent observers to determine prevalence of complex liver cysts. RESULTS 23 (12%) of subjects, had at least 1 complex cyst. Only 8 (4%) were reported to have a complex cyst prospectively, representing an under-reporting rate of 65%. Median total cyst volume was 66-times greater for subjects with complex cysts compared to subjects without (p<0.0001). CONCLUSION Complex hepatic cysts were observed in 12% of ADPKD cases, occurring more frequently in livers with extensive cystic involvement.

Immediate reaction to gadolinium based contrast agent with fatal outcome

We read with great interest the case report of “Fatal anaphylactic reaction to intravenous gadobutrol, a gadoliniumbased MRI contrast agent” by Dr Franckenberg et al. [1] where the 42-years-old patient did not respond to an H2 blocker, steroids, and cardio pulmonary resuscitation (CPR) and dying within 1 hour in spite of being transferred to a University Hospital. The extraordinarily low incidence of immediate-type allergic reactions to GBCAs and the current focus on chelate stability and gadolinium retention has shifted attention away from this important aspect of GBCA safety [2] . However, in situations where there is increased allergic reaction risk it may be useful to consider immediate adverse reaction rates when selecting which GBCA to administer. As an example, gadodiamide has been shown in a recent meta-analysis to have 10-fold lower risk of immediate adverse events compared to gadobutrol [3] . Situations where GBCA allergic reaction risk may be considered more important than GBCA stability include imaging centers which require transferring the patient to a hospital in the event of a life-threatening immediate reaction, with associated delay in critical care. Additional patient risk factors include history of allergic reaction to GBCA or other contrast agents, asthma, atopia, and patients with tenuous health who might not survive anaphylactic shock [3] . Epinephrine IV (0.1 mg administered as 1 ml of 1:10,000 dilution) or IM (0.3 mg administered as 0.3 ml of 1:1000 dilution) is the drug of choice for anaphylaxis [4] and we always maintain the IV after GBCA administration until we are comfortable that the patient is not having any serious reaction. If epinephrine is contraindicated or not available, this also represents a higher risk situation

Bladder diverticuli following injection of onabotulinum toxin A in a patient with multiple sclerosis and autosomal dominant polycystic kidney disease

Highlights • Bladder diverticuli identified following Botox treatment of neurogenic bladder.• Magnetic resonance imaging is useful to detect bladder diverticuli following Botox injections.• Magnetic resonance imaging following Botox treatment of neurogenic bladder may be helpful.

Applications of PET/CT and PET/MR Imaging in Primary Bone Malignancies

Primary bone malignancies are characterized with anatomic imaging. However, in recent years, there has been an increased interest in PET/computed tomography scanning and PET/MRI with fludeoxyglucose F 18 for evaluating and staging musculoskeletal neoplasms. These hybrid imaging modalities have shown promise largely owing to their high sensitivity, ability to perform more thorough staging, and ability to monitor treatment response. This article reviews the current role of PET/computed tomography scanning and PET/MRI in primary malignancies of bone, with an emphasis on imaging characteristics, clinical usefulness, and current limitations.

Relationship of Seminal Megavesicles, Prostate Median Cysts, and Genotype in Autosomal Dominant Polycystic Kidney Disease: Prostate Cysts and Megavesicles in ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) can involve prostate and seminal vesicles but the potential interrelationship of these findings and associations with PKD gene mutation locus and type is unknown.

Arachnoid cysts with spontaneous intracystic hemorrhage and associated subdural hematoma: Report of management and follow-up of 2 cases

Arachnoid cysts are one of the most frequently encountered intracranial space-occupying lesions in daily neurosurgery and neuroradiology practice. Majority of arachnoid cysts, particularly those of smaller sizes, have a benign uneventful lifetime course. Certain symptoms may indicate serious complications related to underlying arachnoid cysts. Hemorrhage is one of the most fearsome complications of arachnoid cysts and almost all reported cases in the literature have undergone surgical correction. In this study, we aimed to present clinical and radiologic follow-up findings in two adult cases of intracranial arachnoid cyst with spontaneous intracystic hemorrhage and associated subdural hematoma, one of which was successfully treated conservatively. In addition, we broadly summarized and discussed pertinent studies in the English literature.