IMAGE QUALITY AND POTENTIAL DOSE REDUCTION USING ADVANCED MODELED ITERATIVE RECONSTRUCTION (ADMIRE) IN ABDOMINAL CT - A REVIEW.

Traditional filtered back projection (FBP) reconstruction methods have served the computed tomography (CT) community well for over 40 years. With the increased use of CT during the last decades, efforts to minimise patient exposure, while maintaining sufficient or improved image quality, have led to the development of model-based iterative reconstruction (MBIR) algorithms from several vendors. The usefulness of the advanced modeled iterative reconstruction (ADMIRE) (Siemens Healthineers) MBIR in abdominal CT is reviewed and its noise suppression and/or dose reduction possibilities explored. Quantitative and qualitative methods with phantom and human subjects were used. Assessment of the quality of phantom images will not always correlate positively with those of patient images, particularly at the higher strength of the ADMIRE algorithm. With few exceptions, ADMIRE Strength 3 typically allows for substantial noise reduction compared to FBP and hence to significant (≈30%) patient dose reductions. The size of the dose reductions depends on the diagnostic task.

Radiologic diagnosis of gastro-oesophageal reflux.

In 149 patients, a standardized radiologic method for the detection of gastro-oesophageal reflux was applied and compared with the results obtained at endoscopy and by a manometric reflux test. Radiologic reflux was recorded in 53 patients, of whom 25 had reflux without abdominal compression and 51 with compression. At least one of the other two types of examination disclosed pathologic conditions in all but 2 of 53 patients. Oesophagitis was significantly more severe among the patients with reflux observed at radiography. The presence of hiatal incompetence with reflux only to the hiatal hernia but not to the oesophagus was not a strong indicator of gastro-oesophageal reflux disease. Hiatal hernia was present in a significantly larger number of the patients with reflux at radiography than in those without reflux. Increased width of the hiatus gave stronger evidence for reflux disease than in patients with a normal hiatus. Thus, the width of the hiatus also had a bearing on the diagnosis of gastro-oesophageal reflux disease.

Radiologic diagnosis of gastro-oesophageal reflux by means of graded abdominal compression.

The aim of the study was to ascertain whether abdominal compression by a standardized technique increases the reliability of the radiologic diagnosis of gastro-oesophageal reflux. Eighty-eight patients were examined by means of a manometric reflux test, 24-hour measurements of pH and endoscopy. The radiologic examination was performed with and without graded abdominal compression, the patient at the same time turning from side to side. When abdominal compression was included the result of the radiologic examination was positive in 31 patients. In the absence of abdominal compression reflux was detected in 11 of these patients. In one patient reflux was detected only without compression. All these 31 patients had one more test positive and in 27 at least 2 more tests were positive. Another 21 patients had reflux disease as indicated by at least 2 of the 3 other tests. The compression technique seems to yield no false positive responses, and proved to be significantly more reliable than examinations without compression.

Radiologic diagnosis of gastro-oesophageal reflux. Comparison of barium and low-density contrast medium.

It has been proposed that the high density of ordinary barium suspensions may complicate the radiologic diagnosis of gastro-oesophageal reflux. For this reason P-contrast was developed (Ferring AB); a contrast medium with the same density as water (1 g/cm3). A comparison of P-contrast and barium (Mixobar Ventrikel 400 mg/ml) was performed in 82 patients. All patients were examined with both contrast media and the findings were compared with those at reflux test at manometry, endoscopy and 24-hour pH monitoring. Another 40 patients and 15 symptom-free controls were examined with two different amounts of barium, 100 ml and 200 ml, to study if the radiologic diagnosis of reflux varied with the volume of contrast medium administered. P-contrast was found to have no advantages over barium for the diagnosis of gastro-oesophageal reflux. The outcome of the radiologic examination was not influenced by the different volumes of barium used.

Esophageal function, radiography, and dysphagia in Sjögren's syndrome.

Esophageal function and anatomy were investigated with manometry, acid perfusion test, acid clearing test, and x-ray in 11 patients with primary Sjögren's syndrome (SS) and in 11 with secondary SS. The manometric investigation revealed minor motor differences in the SS patients as compared to 16 controls, ie, shorter peristaltic contraction time of the whole esophagus, and faster peristaltic velocity preferably in the distal part of the esophagus, while the results from the reflux tests did not differ between patients and controls. Radiographic examination revealed upper esophageal webs in 10% (2/20), and hiatal hernia in 25% (5/20). The dysphagia as reported by 73% of the patients cannot be explained by webs or impaired motor function and is regarded to be secondary to lack of saliva, making the solid bolus passage difficult.

Radiologic findings after fundoplication compared with a pH reflux test and symptoms.

In a follow-up after fundoplication, 61 patients underwent a double contrast examination of the stomach and a radiologic examination to detect any gastro-oesophageal reflux. The radiologic findings were compared with pH reflux test and symptoms. Gastro-oesophageal reflux was found in 7 patients at radiologic examination. None of these patients had an adequate fundoplication at a double contrast examination of the stomach and all had symptoms indicating reflux. Recurrence of gastro-oesophageal reflux may be shown at the radiologic examination and predicted by the morphologic appearances at the double contrast examination.

Scintigraphy, radiography, and acid clearing in dysphagia patients after anti-reflux surgery.

Oesophageal emptying was studied with scintigraphy, radiography, and the acid clearing test (ACT) in 18 patients reporting dysphagia and previously operated on with fundoplication. Radiography with contrast medium, isodense with water, revealed abnormalities in either motility or emptying capacity in 39% (7/18). A A barium meal showed abnormalities--that is, a tight repair, disruption of the fundoplication, or recurrence of the hernia--in 56% (10/18). The ACT was prolonged in 40% (6/15) of the patients. Pathological findings at scintigraphy with a solid bolus were found in 67% (12/18). Even if scintigraphy with a solid bolus is the method that identifies the highest number of patients with impaired oesophageal function among the tests used, it cannot differentiate between functional and anatomical disorders. A barium meal examination is the method of choice when an anatomical disorder is suspected.

Adenocarcinoma of the ethmoid sinuses. A review of 28 cases with special reference to wood dust exposure.

Adenocarcinoma makes up only a small percent of all nasal and paranasal sinus carcinomas, and is most often found in the ethmoid sinuses. Adenocarcinoma of the ethmoid sinuses is known to be associated with exposure to wood dust. Twenty-eight patients with ethmoid adenocarcinomas were collected, mainly during the last decade from a region with approximately 900,000 inhabitants and with a large amount of furniture industries. There were 4 women and 24 men in the study. Twenty of the men were exposed to dust from hardwood for 20 to 55 years (mean, 40 years) which is in accord with other reports and supports data on the increased risk for workers of developing adenocarcinoma of the ethmoid sinuses when exposed to dust from hardwood. Radiologic diagnosis is necessary to delineate the extent of these tumours, and computerized tomography (CT) especially furnishes important information. Most patients received preoperative radiotherapy followed by surgery, 50% of them survived 5 years, which is in accord with other reports.

Paraganglioma involving the larynx.

Paraganglioma is a rare tumor in the upper respiratory tract. More than 30 paragangliomas have been reported arising in the larynx but only a few in the trachea. The organoid arrangements of the cell nests reproduce the classic 'Zellballen' of the normal gland. Neurosecretory granules can be seen at electron microscopy. Angiography may be a valuable diagnostic adjunct. Malignant degeneration may occur. The 44-year-old woman reported had a dumbbell-shaped tumor involving the subglottic larynx but with its largest portion outside the larynx and within the left lobe of the thyroid gland. The tumor may very well have arisen from the inferior laryngeal paraganglia. An important differential diagnosis is hemangiopericytoma, which was the preoperative diagnosis in this case. A laryngectomy including the left lobe of the thyroid gland was performed and there is no sign of local recurrence or metastases 7 years after operation.

Computed tomography in carcinoma of the larynx and piriform sinus.

The conventional methods of examination do not furnish a complete picture of deep extension of carcinoma of the larynx and piriform sinus. Often the only sign of deep invasion is vocal cord fixation. The purpose of this study was to ascertain whether further information in this respect might be provided by computed tomography. The results of examinations by this technique were assessed on the basis of the findings in whole-organ serial sections in the transverse plane in 8 patients with laryngeal and 2 with piriform sinus carcinoma. In 2 further patients not undergoing operation, the findings yielded by CT were compared to the laryngoscopic assessment and the findings at a clinical follow-up after a full course of radiotherapy. CT adds valuable information on the deep invasion of the tumour, especially spread lateral to the arytenoid cartilage, to the laryngeal framework and outside the larynx.

Angiography in laryngeal carcinoma.

Angiography was performed in 8 patients with laryngeal carcinoma. The findings suggest that angiography can provide useful information on deep tumour invasion but further experiences are required before any definite conclusions can be drawn.

Arterial anatomy in the normal larynx and in laryngeal carcinoma. Radiography of specimens.

For a correct selection of patients with laryngeal carcinoma for surgery, especially when partial surgery is contemplated, it is important to ascertain the extent of deep tumour invasion. The usual radiologic methods and microlaryngoscopy have shortcomings in this respect. Angiography of normal specimens demonstrated that the arterial anatomy is fairly constant and characteristic. Specimens from carcinoma patients displayed vascular abnormalities related to deep invasion, as demonstrated at microscopic examination.

Amyloidosis of the larynx.

Amyloidosis of the larynx is a rare disease, accounting for less than 1% of all benign laryngeal 'tumours'. Three cases of this type of lesion are reported--one of the vocal cord, one of the false vocal cord and one of the subglottis and trachea. In 2 of the patients the amyloidosis was localized, while the third was later found also to have an epipharyngeal solitary plasmacytoma with amyloid deposits and in addition amyloidosis of the nasal cavity. However, the amyloidosis in this patient may still be regarded as being localized, as the clinical examination and laboratory tests afforded no evidence of generalized disease. Amyloidosis of the larynx may be manifested as a localized tumour or as a diffuse infiltration. The symptoms and signs will, of course, depend on the site of the amyloid deposit. When the vocal cords are involved hoarseness may result, and this was the most prominent sign in the present cases. The treatment of laryngeal amyloidosis is primarily by endoscopic excision. Amyloid substance has specific staining properties. The Congo red reaction with a green birefringence in polarized light and Phorwhite BBU using fluorescence microscopy are regarded as the most reliable staining reactions. Electron microscopy has revealed a typical fibrillar structure of amyloid.

Radiologic assessment of laryngeal carcinoma. A clinico-pathologic comparison based on whole-organ serial sections.

In 33 patients with laryngeal carcinoma operated upon with laryngectomy, a comparison has been made of the findings yielded by radiography and microlaryngoscopy and a microscopic examination using whole-organ serial sectioning. The radiographic examinations were conventional films, tomography and laryngography. Radiography supplemented in microlaryngoscopy with information of clinical importance. Surface extension of the tumour was fairly accurately assessed preoperatively whereas deep infiltration was not. Major destruction of the anterior part of the thyroid cartilage was correctly diagnosed.

Mechanisms affecting lower oesophageal sphincter opening and oesophageal retention. A combined X-ray and manometry study.

Using simultaneous manometry and cineradiography, oesophageal evacuation was studied while contrast medium was infused via a catheter. The distal half of the oesophagus could be filled with contrast medium without triggering peristalsis. The hydrostatic pressure necessary to open the lower oesophageal sphincter (LES) was of approximately the same magnitude as the pressure gradient between oesophagus and LES. No significant relaxation of the LES could be observed at the initiation of swallowing. The LES may be looked upon not only as a sphincter preventing reflux but also as a gate which must be forced open by food.

Radiology and laryngoscopy for the diagnosis of laryngeal carcinoma.

A comparison is made of the radiologic and clinical findings in 51 patients with laryngeal carcinoma. The radiologic methods comprised conventional films, tomography and laryngography; the clinical examination technique included microlaryngoscopy and the use of a 90 degrees optical instrument. Laryngography was found to be superior to the other two radiologic methods, for the delineation of the tumors. Radiology should be performed before laryngoscopy and biopsy.

The role of CT scanning in the diagnosis of acoustic neuromas.

CT scanning has an important role as a prime investigate technique in the patient with hearing loss and/or vestibular dysfunction. Lesions larger than two cm in size should be further investigated by angiography. Myelography of the posterior fossa remains the only test that can exclude an acoustic neuroma if small or if there is a negative CT scan. Plain films and tomography are used to exclude other lesions.

Radiologic-pathologic correlations in laryngeal carcinoma.

Radiological examinations are a prerequisite for accurate assessment of laryngeal tumors, especially when contemplating partial (voice conservation) surgery. The clinical assessments and preoperative radiographs from five cases have been compared with the histologic findings in whole organ serial sections of the laryngectomy specimens. These studies demonstrated both the accuracies and the deficiencies of the present clinical and radiologic examination methods. The mucosal extension of tumor is accurately assessed by a combination of direct laryngoscopy and radiography. The latter mainly gives information concerning the vertical extent of tumor, especially contrast laryngography. Xeroradiography may give additional information. Deep invasion of tumor with cartilage destruction and spread outside the larynx is often not assessable preoperatively. Circumferential and symmetrical lesions may be missed radiologically as much of the interpretation is based on asymmetry. New methods must be developed to assess the deep invasion of tumor. The necessity of a close liaison between the laryngologist, radiologist, and clinical pathologist is stressed.