Patients undergoing recurrent CT scans: assessing the magnitude

To assess percent of patients undergoing multiple CT exams that leads to cumulative effective dose (CED) of ≥ 100 mSv and determine their age distribution. Data was retrieved retrospectively from established radiation dose monitoring systems by setting the threshold value of 100 mSv at four institutions covering 324 hospitals. The number of patients with CED ≥ 100 mSv only from recurrent CT exams during a feasible time period between 1 and 5 years was identified. Age and gender distribution of these patients were assessed to identify the magnitude of patients in the relatively lower age group of ≤ 50 years. Of the 2.5 million (2,504,585) patients who underwent 4.8 million (4,819,661) CT exams during the period of between 1 and 5 years, a total of 33,407 (1.33%) patients received a CED of ≥ 100 mSv with an overall median CED of 130.3 mSv and maximum of 1185 mSv. Although the vast majority (72–86%) of patients are > 50 years of age, nearly 20% (13.4 to 28%) are ≤ 50 years. The minimum time to accrue 100 mSv was a single day at all four institutions, an unreported finding to date. We are in an unprecedented era, where patients undergoing multiple CT exams and receiving CED ≥ 100 mSv are not uncommon. While underscoring the need for imaging appropriateness, the consideration of the number and percent of patients with high exposures and related clinical necessities creates an urgent need for the industry to develop CT scanners and protocols with sub-mSv radiation dose, a goal that has been lingering. • We are in an era where patients undergoing multiple CT exams during a short span of 1 to 5 years are not uncommon and a sizable fraction among them are below 50 years of age. • This leads to cumulative radiation dose to individual patients at which radiation effects are of real concern. • There is an urgent need for the industry to develop CT scanners with sub-mSv radiation dose, a goal that has been lingering.     

Persistent and recurrent hyperparathyroidism: assessment with gadopentetate dimeglumine-enhanced MR imaging

The effect of gadopentetate dimeglumine on signal intensity of abnormal parathyroid glands was assessed in 14 patients with persistent and recurrent hyperparathyroidism. Non-contrast material-enhanced T1- and T2-weighted spin-echo images were compared with T1-weighted images obtained 1 minute and 10 minutes after administration of gadopentetate dimeglumine. Percentage of contrast between the abnormal gland and surrounding tissue was determined with the use of skeletal muscle, subcutaneous fat, and thyroid gland as reference tissues. All 11 abnormal parathyroid glands showed low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Gadopentetate dimeglumine significantly increased the signal intensity enhancement ratio of all abnormal parathyroid glands, causing increased percentage of contrast relative to the thyroid gland and skeletal muscle on T1-weighted images. However, the percentage of contrast relative to these tissues was even greater on nonenhanced T2-weighted images. Thus, gadopentetate dimeglumine can substantially enhance the signal intensity of abnormal parathyroid glands and improve differential contrast with some neighboring tissues on T1-weighted images, but it does not improve contrast with surrounding tissue beyond that achieved on T2-weighted images.     

Hypertrophic cranial pachymeningitis: assessment with CT and MR imaging

Three patients with diffuse idiopathic cranial pachymeningitis with predominant involvement of the tentorium and falx are reported. Progressively increasing headaches were the usual symptoms, along with ataxia and various cranial nerve palsies. CT in all cases and MR imaging in two cases detected isolated thickened dura mater. In one case, MR depicted dural involvement as a very large, hypointense area with fine hyperintense edges on T2-weighted images. Microscopic examination of thickened dura revealed extensive fibrotic tissue with a chronic inflammatory infiltrate containing lymphocytes, plasma cells, and scattered eosinophils; these findings closely paralleled the MR features. Only four cases with similar pathologies have been described, all before the advent of CT and MR. We discuss the different causes of thickened dura mater as well as the significance of the fact that dural thickening can be responsible for occlusion of the dural sinuses. Cranial pachymeningitis is a rarely reported disease that can resemble other disorders associated with tentorial thickening; CT and MR can help differentiate it from these other disorders.     

Cochlear implant candidates: assessment with CT and MR imaging

Eighty-seven patients with severe to profound hearing loss were evaluated for possible placement of a multichannel cochlear implant hearing device. After initial clinical screening, 42 patients underwent computed tomographic (CT) examination. Five of these patients were also examined with magnetic resonance (MR) imaging. Twenty-two patients received implants. CT of the middle and inner ear was normal in 24 patients (57.1%) and showed labyrinthine ossification in 12 (28.6%), cochlear or fenestral otosclerosis (or both) in four (9.5%), and congenital cochlear malformation in two (4.8%). The information provided by CT was used to (a) exclude patients in whom multichannel cochlear implantation would most likely be unsuccessful (owing to obliterative labyrinthine ossification, or congenital cochlear malformation, severe cochlear, or fenestral otosclerosis), (b) help select the best ear for implantation, and (c) provide a preoperative picture of normal variants and avoidable surgical pitfalls. MR experience is limited but assessment of the size of the cochlear nerve and the membranous labyrinth is possible with this modality and may provide additional information in the evaluation of these patients.     

Patients with partial seizures: evaluation by MR, CT, and PET imaging

Fifty patients who experienced partial seizures were imaged with computed tomography (CT) and magnetic resonance imaging (MR); 14 of these also had imaging studies of local cerebral glucose metabolism with positron emission tomography (PET). Thirteen patients with attenuation abnormalities on CT scans also had abnormal signals on MR images; ten other patients had MR-image signal abnormalities but normal CT scans. In all seven patients undergoing PET who had MR-signal and sometimes also CT-attenuation abnormalities, areas of metabolic asymmetry were present. Positive PET scans were also seen in three patients with no evidence of abnormality on CT and MR studies. Focal cerebral substance loss on CT and MR studies, present in 21 patients, did not correlate well with electroencephalographic findings. MR is utilized as the initial imaging procedure in patients with partial seizures because it is more readily available and less invasive than PET and more sensitive than CT scanning.     

Radiotherapy of non-malignant diseases: principles and recommendations

The plenty options and high quality of radiation therapy for non-malignant disorders is not well known outside the field of radiology. It is necessary to transfer this information to cooperating general practitioners, surgeons, orthopedics and other specialists. To warrant quality assurance and quality control and to allow a uniform performance of radiotherapy of non-malignant conditions, general guidelines and recommendations according to the German Working Group of Scientific Medical Societies are useful. This paper summarizes the essential aspects of radiotherapy for non-malignant diseases: indication of, informed consent for, documentation and conduct of radiation therapy for non-malignant diseases using orthovoltage equipment and specific recommendations for follow up examinations. Radiotherapy concepts for non-malignant diseases are summarized.     

The surgical bed after BCNU polymer wafer placement for recurrent glioma: serial assessment on CT and MR imaging

OBJECTIVE: The objective of our study was to describe the CT and MR imaging appearances of the surgical bed in the brains of patients receiving biodegradable polymers impregnated with N, N'1, 3-Bis-(2-chloroethyl)-N-nitrosourea (BCNU) for recurrent glioma and to determine whether patients receiving placebos could be differentiated from those receiving BCNU based on the pattern and growth kinetics of tumor recurrence. MATERIALS AND METHODS: The CT and MR images of 20 patients who underwent surgery for resection of recurrent high-grade gliomas and placement of intratumoral wafers (11 received BCNU polymer wafers, nine received control wafers) were analyzed for wafer appearance, volume of gas in the tumor bed, and volume of enhancement on serial scans. RESULTS: Wafers appeared as linear hyperdense structures on CT and as linear low-signal-intensity structures on MR imaging and caused no significant enhancement. In the BCNU polymer group, gas volume was 4.0 +/- 3.4 cm(3) (mean +/- SD), whereas gas volume was 1.6 +/- 3.0 cm(3) for the placebo group (Mann-Whitney test, p = 0.03). A trend toward linear rather than exponential recurrent tumor growth was identified for the BCNU polymer group but not for the placebo group. CONCLUSION: BCNU polymer wafers have a specific appearance on CT and MR imaging with which radiologists should be familiar: gas in the surgical bed is an expected transient finding, and tumor regrowth in patients receiving BCNU polymer wafers appeared to occur at a slower rate than in those receiving the placebo.     

Preoperative coronary risk assessment with dual-source CT in patients undergoing noncoronary cardiac surgery

Purpose

The aim of our work was to assess the role of dual-source computed tomography (DSCT) in the preoperative evaluation of coronary artery disease in patients scheduled for noncoronary cardiac surgery.

Materials and methods

One hundred patients were prospectively evaluated. Patients negative for coronary disease at DSCT (n=81) underwent surgery without coronary angiography. Patients positive for significant lesions or with nondiagnostic image quality due to artefacts or severe calcifications underwent coronary angiography (n=19) and were excluded from the study. In patients who underwent surgery with only a DSCT diagnosis, we evaluated the frequency of major adverse cardiac events (MACEs) during the perioperative period and at 3 months follow-up.

Results

No MACEs were recorded during the perioperative period; three noncardiac complications (one surgical revision for bleeding, one cardiac tamponade and one respiratory insufficiency) and one death related to severe respiratory insufficiency were observed. None of the 80 patients had MACEs during the 3-month follow-up period.

Conclusions

Coronary evaluation with DSCT is able to rule out the presence of coronary disease in patients scheduled for cardiac surgery, without the need for coronary angiography confirmation. Patients with significant stenosis or nondiagnostic image quality should be referred for coronary angiography.     

High-resolution CT: pre-operative assessment of chronic and recurrent rhinosinusitis

The better understanding of chronic and recurrent rhinosinusitis and the advance in endoscopic endonasal surgery have modified the radiological pre-operative investigation of this condition. The ethmoid labyrinth, not accessible to the endoscope, may be explored by axial and coronal high-resolution thin section (2 mm) CT. We have reviewed 100 CT scans with endoscopic correlation in order to assess the accuracy of this pre-operative method.This anatomical study reveals the presence and extent of parasinus diseases which are usually concentrated in the area of the ostiomeatal unit. The anatomic variations of the lateral nasal wall that have been reporded as predisposing to sinusitis and the morphologic variations altering the relationships of the ethmoid with the orbits and the brain were also studied. This pre-operative radiological assessment is currently necessary for functional and safe surgery.Correspondence to: J. C. FerriePaper presented at ECR 1991     

Absorbed doses on patients undergoing tomographic exams for pre-surgery planning of dental implants

The thermoluminescent (TL) dosimetry was used to measure entrance skin absorbed doses at anatomical points close to critical organs of patients undergoing tomographic techniques as part of a pre-surgery planning for dental implants. The dosimetric procedure was applied in 19 patients, and absorbed doses could be measured with a combined uncertainty down to 14%. Results showed that patient doses may be increased by a factor of 20 in the helical computed tomography compared to panoramic and spiral conventional tomographic exams.     

Oxygen-enhanced MRI for patients with connective tissue diseases: Comparison with thin-section CT of capability for pulmonary functional and disease severity assessment

Purpose

To prospectively and directly compare oxygen-enhanced (O₂-enhanced) MRI with thin-section CT for pulmonary functional loss and disease severity assessment in connective tissue disease (CTD) patients with interstitial lung disease (ILD).

Materials and methods

Thin-section CT, O₂-enhanced MRI, pulmonary function test and serum KL-6 were administered to 36 CTD patients with ILD (23 men, 13 women; mean age: 63.9 years) and nine CTD patients without ILD (six men, and three women; mean age: 62.0 years). A relative-enhancement ratio (RER) map was generated from O₂-enhanced MRI and mean relative enhancement ratio (MRER) for each subject was calculated from all ROI measurements. CT-assessed disease severity was evaluated with a visual scoring system from each of the thin-section CT data. MRER and CT-assessed disease severities of CTD patients with and without ILD were then statistically compared. To assess capability for pulmonary functional loss and disease severity assessment in CTD patients, correlations of MRER and CT-assessed disease severity with pulmonary functional parameters and serum KL-6 in all subjects were statistically determined.

Results

MRER and CT-assessed disease severity showed significant differences between CTD patients with (MRER: 0.15 ± 0.08, CT-assessed disease severity: 13.0 ± 7.4%) and without ILD (MRER: 0.25 ± 0.06, p = 0.0011; CT-assessed disease severity: 1.6 ± 1.6%, p < 0.0001). MRER and CT-assessed disease severity correlated significantly with pulmonary functional parameters and serum KL-6 in all subjects (0.61 ≤ r ≤ 0.79, p < 0.05).

Conclusion

O₂-enhanced MRI was found to be as useful as thin-section CT for pulmonary functional loss and disease severity assessment of CTD patients with ILD.     

Prostatic carcinoma: staging by clinical assessment, CT, and MR imaging

The sensitivity, specificity, accuracy, and positive and negative predictive values of clinical assessment, computed tomography (CT), and magnetic resonance (MR) imaging were compared in the differentiation of stage B from stage C prostatic carcinoma. Forty-six patients who had undergone radical prostatectomy were included in the study. Surgical-pathologic staging was considered the "truth measure." Clinical staging had an accuracy of 61%, and CT, 65%. Accuracy for MR imaging depended on the instrument parameters and plane of section used. When only transverse T1-weighted images were analyzed, MR accuracy was 61%. However, when transverse T1- and T2-weighted images supplemented by additional T2-weighted coronal or sagittal images were studied, accuracy increased to 83%. At present, MR imaging is the most accurate diagnostic modality for the local staging of carcinoma of the prostate, but for optimal results, multiple sequences and two orthogonal planes of imaging are needed.     

Diagnostic and clinical benefit of combined coronary calcium and perfusion assessment in patients undergoing PET/CT myocardial perfusion stress imaging

Background  

A limitation of stress myocardial perfusion imaging (MPI) is the inability to detect non-obstructive coronary artery disease (CAD). One advantage of MPI with a hybrid CT device is the ability to obtain same-setting measurement of the coronary artery calcium score (CACS).     

应用多层螺旋CT对人工心脏瓣膜评估:附83例91个人工瓣膜影像学特点分析

目的多层螺旋CT(MDCT)已经显示出评估人工心脏瓣膜(PHV)的潜在价值。本研究旨在评估不同类型PHV的影像质量,并确定哪些类型PHV适合用MDCT来评价。     

Prosthetic heart valve assessment with multidetector-row CT: imaging characteristics of 91 valves in 83 patients

Objectives  

Multidetector CT (MDCT) has shown potential for prosthetic heart valve (PHV) assessment. We assessed the image quality of different PHV types to determine which valves are suitable for MDCT evaluation.     

Head and neck tumors: imaging recurrent tumor and post-therapeutic changes with CT and MRI

OBJECTIVE: To evaluate criteria for detection of tumor recurrence and post-treatment changes in patients with head and neck malignancies in computed tomography (CT) and magnetic resonance imaging (MRI). METHODS AND MATERIALS: Thirty-nine patients with head and neck carcinoma receiving radiochemotherapy were examined before, during and after therapy with MRI. Changes in signal intensity were correlated to histology or clinical course. Three hundred and thirty-one patients with head and neck malignancies were examined with CT after therapy. CT diagnoses were correlated with histology or clinical course. RESULTS: Main criteria for recurrent/residual tumor in MRI was infiltrative mass with high signal intensity in T2-weighted images and enhancement after Gd-DTPA in T1-weighted images. Radiation-induced changes led to false positive diagnosis in 46% in the interval up to 3 months after therapy and in 58% in the interval 3-6 months after therapy. The combination of a circumscribed, infiltrative mass with contrast enhancement in CT had a sensitivity of 86% and a specificity of 80%. CONCLUSION: CT could accurately demonstrate postoperative changes and tumor recurrence. MRI had advantages in differentiation of tumor and scar, but edema after radiation therapy can spoil diagnosis.     

Retropharyngeal space: evaluation of normal anatomy and diseases with CT and MR imaging

A retrospective analysis of computed tomographic (CT) and magnetic resonance (MR) images and clinical records of 39 patients with retropharyngeal space (RPS) lesions was completed. The review was undertaken to answer the following questions: (a) what is the spectrum of lesions of the RPS? (b) what imaging features mark a lesion as originating in the RPS? and (c) is there a difference between the radiologic pattern of the suprahyoid and infrahyoid portions of the neck? Of the 39 patients in the study, nine had RPS infections, 17 had RPS malignancies, two had benign tumors, seven had RPS pseudotumors, and four had hematoma or air in the RPS after trauma. RPS lesions demonstrated two distinct radiologic patterns: a nodal pattern and a nonnodal pattern. The nodal pattern, found only in the suprahyoid neck, occurs when infection or tumor begins in the lymph nodes of the RPS. The lesions may be unilateral or bilateral, but the middle part of the RPS is spared. The nonnodal pattern, found primarily in the infrahyoid RPS, results when the infection or tumor directly invades the RPS or goes beyond the nodes of the RPS. The nonnodal lesion appears rectangular and spans the RPS from side to side.