Letters to the Editor Musculoskeletal Imaging: MRI versus Three Dimensional Spiral CT Dear Editor,
T
his is with reference to the original article titled “Three Dimensional Spiral CT Imaging of Musculoskeletal System: Application & Advantages” (MJAFI 2005; 61:133-8). Comparison of application of Three dimensional spiral CT imaging with MRI in imaging of Musculoskeletal System continues to evoke mixed response. However, at present, the scale is clearly tilted towards Magnetic Resonance Imaging in most musculoskeletal conditions except in skeletal trauma. In view of this, following comments are offered on this article: The authors have used 3-D CT Imaging in evaluation of bone tumors. The authors’ contention is that CT is not only as efficacious but is superior to MRI in detection of cortical destruction of calcification. However, it is brought to the attention of the readers that the main aim of imaging studies in bone tumors is to establish the extent of lesion, detect the bone marrow involvement, skip lesions, satellite lesions, to define aggressive nature of lesion and to establish extent of soft tissue involvement. For all these aims, MRI remains the imaging modality of choice and is superior to 3-D CT Scan. With exception of densely sclerotic lesions e.g. osteoid osteoma, MRI has replaced CT scan for the assessment of skeletal tumors [1]. The authors have also used 3-D CT for evaluation of avascular necrosis of femoral head while accepting at the same time that MRI is considered as the gold standard. MRI can detect stage-I avascular necrosis of the femoral head whereas 3-D CT detects from stage – II onwards only [2,3]. The reason for 3-D CT imaging preference is not clear. Last but not the least, the often ignored issue of radiation exposure and safety needs to be considered. In this study, every
patient underwent radiation exposure to obtain 180 to 320 CT images. Some of these patients also underwent repeat imaging studies. This is a highly significant level of radiation. Doing a 3-D CT imaging study in a patient with a skeletal tumor or avascular necrosis of femoral head (where MRI is the established gold standard) raises safety issues as well as ethical issues. It is hoped that patients undergoing these studies were fully informed of these issues and necessary informed consent was obtained for undergoing a relatively less revealing imaging study with very high radiation exposure. As the authors have not declared this study to be either experimental or comparative (with MRI), ethical issues regarding patient safety and relevance of investigations need due consideration. As the study was conducted at a tertiary care centre, it is not likely that facilities of MRI were not available locally (In service hospital/ in local civil medicare set up). References 1. Dexter Witte, Magnetic Resonance Imaging in Orthopaedics. In:Campbell’s Operative Orthopaedics. 9 th edi. Mosby. 1998; 25. 2. Saitos S, Ohzono K, Ono K. Minimal osteonecrosis as a segmental infarct within the femoral head. Clin Orthop. 231:35, 1900. 3. Seiler JG III, Christier MJ, Homra L: Correlation of the findings of magnetic resonance imaging with those of bone biopsy in patients who have stage I or II ischaemic necrosis of the femoral head. J Bone Joint Surg. 71-A:28, 1989. Maj Narinder Kumar Classified Specialist (Orthopaedics), Base Hosp, Lucknow.
REPLY At the very outset the authors wish to thank the reader for the keen interest shown in the article. Rarely does one find such a response to published articles. The points raised by the reader are well taken, however at the same time we wish to clarify the issues. This study was not a comparative evaluation of CT/3-D CT versus MRI, but a presentation of our experience with 3-D CT in various disorders of the musculoskeletal system. This study relates to the period when MRI was not available in the centre. It further needs to be reiterated that though MRI is a more recent imaging modality with definite advantages it will be incorrect to say that it has replaced CT, in fact at times both CT and MRI are complementary in providing a comprehensive diagnosis. Anatomic information gained from 3D CT can be useful in planning oncologic therapy, whether surgery or radiation therapy. Three-dimensional images are especially valuable in anatomically complex areas such as the ribs, pelvis, and shoulder and have proved useful in providing information to accurately assess the anatomic localization of the lesion. In fact some authors have suggested inclusion of volume rendered 3-D imaging as part of routine imaging protocol in the evaluation of neoplastic diseases of the bone [1]. An integrated 2-D and 3-D CT approach allows precise and rapid, imaging for initial
assessment, planning of radiation therapy, en bloc resection or limb-salvage surgery and also in evaluation of therapeutic response/ recurrence in musculoskletal tumours[2]. For evaluation of avascular necrosis, as stated in the text, MRI continues to be the gold standard. Much also depends on the availability of a specific modality and definitely 3-D CT is not the preferred modality. Clarification needs to be made regarding the protocol for 3-D reconstruction adopted in this study, although 190 to 320 images were obtained in some of the patients, this does not mean that as many CT slices were taken. A significant advancement of Spiral CT is the ability to post-process the images. The base images which are acquired are reconstructed, using dedicated software, at narrower intervals to get more number of slices. This gives better 3-D images and at the same time helps in reducing the radiation dose to the patient. As far as radiation safety is concerned, patients were informed of the potential hazards of radiation and an informed consent was obtained from all of them. Not withstanding this, every modality has its advantages and disadvantages and one has to consider in totality giving due consideration to the availability, faster study time, cost and advantages of modality.
208 References 1. Pretorius ES and Fishman EK. Volume-rendered Threedimensional Spiral CT: Musculoskeletal applications. Radiographics 1999; 19:1143-60.
Letters to the Editor 2. Magid D. Two-dimensional and three-dimensional computed tomographic imaging in musculoskeletal tumors. Radiol Clin North Am 1993; 31(2): 425-47. Wg Cdr A Alam Associate Prof (Radiodiagnosis) AFMC, Pune-40.
Breast Feeding and Antenatal Preparation Dear Editor,
T
his is with reference to the article titled “Maternal and neonatal factors adversely affecting breastfeeding in the perinatal period”. (MJAFI 2005; 61: 216-19.). We have the following comments upon the case report: The authors must be congratulated for highlighting various risk factors which may interfere with successful establishment of breast feeding in the mother-baby pair. In addition to the various factors mentioned by the authors, antenatal preparation for breast feeding remains very important for successful lactation. The antenatal preparation involves breast examination to look for retracted nipples in the antennal clinic and advice to the mother about advantages of breastfeeding her baby. This helps in motivation of the mother and successful establishment of oxytocin reflex (milk ejection reflex) at the time of breastfeeding. Unfortunately this important component of the strategies to enhance the success of breastfeeding is often overlooked.
We carried out a survey of 100 successive mothers who delivered in our hospital. The mothers had been followed up at antenatal clinics at various services health centres locally and referred for delivery to our hospital. Of the 100 mothers, only 22 mothers had breast examination done in the antenatal period and only 17 mothers had received any advice about breast feeding. Seven mothers were found to have retracted nipples in the post natal period which interfered with establishement of successful lactation. These mothers needed special counselling and support for management of sore nipples. Earlier detection of retractile nipples in the antenatal period followed by appropriate maneuvers to make the nipples protractile would have helped in avoiding the breast feeding problems. The antenatal preparation for breast feeding is essential for ensuring the success of breast feeding in the perinatal period. Wg Cdr Daljit Singh*, Fg Offr Amit Kumar+, Lt Col B Ravichander# *# Classified Specialist(Paediatrics), Command Hosp (AF), Bangalore-7. +Medical Officer, 35 Wing c/0 56 APO.
REPLY Dear Editor,
W
e thank the author(s) for their appreciation of our work reported in the article “Maternal and neonatal factors adversely affecting breast feeding in the perinatal period “[1]. We fully agree with the author[s] contention that antenatal preparation of the prospective mother including counselling, examination and management of any anatomical problems with her breasts forms a very important part of effort at ensuring successful breastfeeding. Our colleagues in the Department of Obstetrics at the tertiary care hospital have been rendering commendable service in this field and as mentioned in the article, regular antenatal counseling for breastfeeding is an integral part of the obstetric services. Examination of the mother’s breast is also being done in all prospective mothers
antenatally though this was not specifically mentioned in our article. We thank the author[s] of the above letter for their comments and once again express our full agreement with their observation that antenatal counselling and examination of the breasts of prospective mothers plays an extremely important part in preparing them for successful lactation after childbirth. References 1. Narayan S, Natarajan N, Bawa KS. Maternal and neonatal factors adversely affecting breastfeeding in the perinatal period. MJAFI 2005; 61: 216-9. Surg Cdr S Narayan Classified Specialist(Pediatrics), INHS ASVINI, Mumbai-5.
MJAFI, Vol. 62, No. 2, 2006
