Computers are an integral part of modern radiology equipment. In the first half of this two-part article, we dwelt upon some fundamental concepts regarding computer hardware, covering components like motherboard, central processing unit (CPU), chipset, random access memory (RAM), and memory modules. In this article, we describe the remaining computer hardware components that are of relevance to radiology. "Storage drive" is a term describing a "memory" hardware used to store data for later retrieval. Commonly used storage drives are hard drives, floppy drives, optical drives, flash drives, and network drives. The capacity of a hard drive is dependent on many factors, including the number of disk sides, number of tracks per side, number of sectors on each track, and the amount of data that can be stored in each sector. "Drive interfaces" connect hard drives and optical drives to a computer. The connections of such drives require both a power cable and a data cable. The four most popular "input/output devices" used commonly with computers are the printer, monitor, mouse, and keyboard. The "bus" is a built-in electronic signal pathway in the motherboard to permit efficient and uninterrupted data transfer. A motherboard can have several buses, including the system bus, the PCI express bus, the PCI bus, the AGP bus, and the (outdated) ISA bus. "Ports" are the location at which external devices are connected to a computer motherboard. All commonly used peripheral devices, such as printers, scanners, and portable drives, need ports. A working knowledge of computers is necessary for the radiologist if the workflow is to realize its full potential and, besides, this knowledge will prepare the radiologist for the coming innovations in the 'ever increasing' digital future.

The objective of the study was to study the magnetic resonance imaging (MRI) features of Hirayama disease on a 3 Tesla MRI scanner. Nine patients with clinically suspected Hirayama disease were evaluated with neutral position, flexion, contrast-enhanced MRI and fast imaging employing steady-state acquisition (FIESTA) sequences. The spectrum of MRI features was evaluated and correlated with the clinical and electromyography findings. MRI findings of localized lower cervical cord atrophy (C5-C7), abnormal curvature, asymmetric cord flattening, loss of attachment of the dorsal dural sac and subjacent laminae in the neutral position, anterior displacement of the dorsal dura on flexion and a prominent epidural space were revealed in all patients on conventional MRI as well as with the dynamic 3D-FIESTA sequence. Intramedullary hyperintensity was seen in four patients on conventional MRI and on the 3D-FIESTA sequence. Flow voids were seen in four patients on conventional MRI sequences and in all patients with the 3D-FIESTA sequence. Contrast enhancement of the epidural component was noted in all the five patients with thoracic extensions. The time taken for conventional and contrast-enhanced MRI was about 30-40 min, while that for the 3D-FIESTA sequence was 6 min. Neutral and flexion position MRI and the 3D-FIESTA sequence compliment each other in displaying the spectrum of findings in Hirayama disease. A flexion study should form an essential part of the screening protocol in patients with suspected Hirayama disease. Newer sequences such as the 3D-FIESTA may help in reducing imaging time and obviating the need for contrast.

The susceptiblity effect in magnetic resonance imaging (MRI) has been recognized for long and often has been considered undesirable, producing unnecessary noise. Susceptibility-weighted imaging (SWI) aims at exploiting this effect to provide a different type of contrast that is suited for vascular imaging. We describe five different cases in which SWI was found useful to delineate the underlying ischemia or to arrive at the corect diagnosis.

Transient splenial lesions (TSL) of the corpus callosum are uncommon radiologic findings that are seen in a number of clinical conditions with varied etiologies. They were first described a decade earlier in patients with epilepsy and hence were thought to be seizure or seizure therapy related. Subsequently, more cases were described by different observers in diseases with different etiologies, and the list is still increasing. Awareness of these lesions is necessary as they are an uncommon finding and have to be differentiated from other infective/noninfective causes. MRI is the imaging modality of choice as these lesions are not seen on routine noncontrast CT scan. The authors here describe two cases which showed TSL, with complete/partial resolution on follow-up scans. The authors also present a review of the literature.

We present a case of persistent primitive hypoglossal artery (PPHA) associated with Chiari II malformation and discuss the clinical implications. There has been one reported case of PPHA associated with Chiari 1 malformation, but none in association with Chiari II. Our patient also had a widened hypoglossal canal, with cerebrospinal fluid (CSF) sac herniation through it.

Background: The styloid process is an anatomical structure, whose clinical importance is not well understood. Proper clinical and radiographic evaluation can detect an elongated styloid process and calcification of the stylohyoid ligament. It has been reported that 2 - 28% of the general population show radiographic evidence of mineralization of a portion of the stylohyoid chain. The elongated styloid process may be symptomatic in many cases. Panoramic radiography is the best imaging modality to view the styloid process bilaterally. Aim: To assess the styloid process on digital panoramic radiographs. Materials and Methods: The study was conducted on 500 digital panoramic radiographs available in the archives of our department as soft copies. These radiographs were taken using a digital panoramic system. The radiographic length of the styloid process was measured on both sides using the measurement toolbars on the accompanying analysis software. For statistical analysis we used the unpaired t test, Chi-square test, and one-way ANOVA test, as necessary. Results: The average length of the left styloid was 25.41 ± 6.32 mm and that of the right styloid was 25.53 ± 6.62 mm. The length of both styloids increased with age and males had longer styloids than females. Elongated styloids were present in 19.4% of the panoramic radiographs. Langlais type I elongated styloids and a partial calcification pattern were more common than others. Conclusion: Panoramic radiography is useful for detection of an elongated styloid process and / or ossification of the stylohyoid ligament in patients with or without symptoms, and helps avoid a misdiagnosis of tonsillar pain or pain of dental, pharyngeal, or muscular origin.

Congenital nasal pyriform aperture stenosis (CNPAS) is a rare cause of nasal airway obstruction that clinically mimics choanal atresia, but needs to be differentiated from the latter because of the widely divergent modes of management. We present a case of CNPAS, to highlight the importance of recognizing the classic signs of CNPAS on cross-sectional imaging.

Tennis leg is caused by a rupture of the medial head of the gastrocnemius muscle, usually at its distal musculotendinous junction region. However, tears in this muscle and its tendon are also included under the term 'tennis leg'. It is seen regularly in practice and is an important cause of a painful calf. The common USG findings include: disruption of the pinnate pattern of the distal medial gastrocnemius, usually near the junction of the triceps surae (which is the echogenic line between the gastrocnemius, the soleus, and the plantaris muscles), fluid tracking along the fascia, adjacent hematoma, and intramuscular tears as well as hematomas. USG is useful for confirming the diagnosis, excluding other causes of a painful calf, for assessing the severity of the disease, and in follow-up.

For imaging, the brachial plexus is a technically and anatomically challenging region of the peripheral nervous system. MRI has a central role in the identification and accurate characterization of malignant lesions arising here, as also in defining their extent and the status of the adjacent structures. The purpose of this pictorial essay is to describe the MRI features of primary and secondary malignant brachial plexopathies and radiation-induced brachial nerve damage.

Aim: To define a range of apparent diffusion coefficient values in spinal tuberculosis and to evaluate the sensitivity of diffusion-weighted magnetic resonance imaging (DW-MRI) and apparent diffusion coefficient values in patients of spinal tuberculosis. Materials and Methods: This study was conducted over a period of 20 months and included 110 patients with a total of 230 vertebral bodies. The study was performed in two parts. The first part included all patients of known tuberculosis and patients with classical features of tuberculosis. The second part included patients with spinal pathology of indeterminate etiology. All the patients underwent a routine MRI examination along with diffusion sequences. The apparent diffusion coefficient (ADC) values were calculated from all the involved vertebral bodies. Results: The mean ADC value of affected vertebrae in first part of the study was found to be 1.4 ± 0.20 ×10 ^-3 mm ² /s. This ADC value was then applied to patients in the second part of study in order to determine its ability in predicting tuberculosis. This range of ADC values was significantly different from the mean ADC values of normal vertebrae and those with metastatic involvement. However, there was an overlap of ADC values in a few tuberculous vertebrae with the ADC values in metastatic vertebrae. Conclusion: We found that DW-MRI and ADC values may help in the differentiation of spinal tuberculosis from other lesions of similar appearance. However, an overlap of ADC values was noted with those of metastatic vertebrae. Therefore diffusion imaging and ADC values must always be interpreted in association with clinical history and routine MRI findings and not in isolation.

Colorectal cancer (CRC) can recur locoregionally or at distant sites. Timely diagnosis of recurrence is of paramount importance, as radical treatment of the localized disease can prolong survival. Fluorodeoxyglucose positron emission tomography / computed tomography (PET / CT) is routinely used in restaging and surveillance of colorectal cancer, as it can demonstrate recurrent disease with good accuracy. This article illustrates the spectrum of standard as well as unusual patterns of local recurrence and distant metastases of colorectal cancer.

Aim: The purpose of this study was to assess the value of Doppler evaluation of left gastric vein hemodynamics when monitoring portal hypertension patients, by correlating Doppler ultrasonography (USG) parameters with the severity of esophageal varices and occurrence of variceal bleeding. Methods: This study was carried out on 100 patients using Doppler USG and endoscopy. Forty-seven of these were patients with cirrhosis with portal hypertension, who had not had a recent variceal bleed (group 1) and 26 were patients with cirrhosis with portal hypertension, with a recent history of bleeding (group 2). The control group comprised of 27 subjects who did not have liver disease or varices on endoscopy (group 3). The hemodynamic parameters, namely the diameter of the left gastric vein and the direction and flow velocity in the vessel, were compared in these groups, with the grade of esophageal varices. Results: Hepatofugal flow velocity in the left gastric vein was higher in patients with large-sized varices compared to those patients with small-sized varices (P < 0.001). The left gastric vein hepatofugal flow velocity was higher in patients with a recent variceal bleed than in those patients without a history of a recent variceal bleed (P < 0.0149). Large-sized varices were more commonly found in patients with a history of a recent variceal bleed (P < 0.0124). Conclusion: Left gastric vein hemodynamics were found to correlate with the severity of the varices and the occurrence of recent variceal bleed in patients with cirrhosis with portal hypertension. Evaluation of the left gastric vein portal dynamics could be helpful in monitoring the progress of the disease in these patients.

Torsion of the greater omentum is a rare acute abdominal condition that is seldom diagnosed preoperatively. We report the characteristic computed tomography (CT) scan findings and the clinical implications of this unusual diagnosis in a 41-year-old man, who also had longstanding right inguinal hernia. Awareness of omental torsion as a differential diagnosis in the acute abdomen setting is necessary for correct patient management.

Ovarian cystadenofibroma is a relatively rare benign ovarian tumor that contains both epithelial and fibrous stromal components. The appearance of cystadenofibroma on imaging is often complex; cystic- to solid-appearing masses may be visualized and it often resembles a malignant tumor. Owing to the fibrous component of this tumor, MRI shows low-signal intensity on T2W images. This finding may help a radiologist make a preoperative diagnosis of this tumor and thus perhaps avoid aggressive surgical management.

Congenital posterior urethral diverticulum is an uncommon anomaly, sometimes complicated by infection or calculi formation. A conventional voiding cystourethrogram (VCUG) is the most commonly used diagnostic modality. Dynamic magnetic resonance imaging (MRI) has not been frequently described in this entity. We describe a case of posterior urethral diverticulum complicated with secondary calculi, where the patient was evaluated using dynamic MRI and conventional VCUG.

Endoscopic plastic biliary stent insertion is a minimally invasive, well-established procedure for the management of benign biliary pathology. We report a case of a migrating stent for over two days, which finally got impacted at the ileocecal junction, leading to intestinal obstruction and obstructive biliopathy. Radiological findings depicted the exact site of the dislodged biliary stent and its related complications, both of which were successfully treated in a nonoperative stepwise manner.

Background: Omental biopsy has conventionally been performed using a surgical approach. USG-guided omental biopsy is a safe and effective alternative. The purpose of this study was to assess the utility of USG guidance for biopsy of the greater omentum. Study design: Retrospective study. Materials and Methods: We retrospectively reviewed all omental biopsies performed under USG guidance from April 2006 to March 2010 in a tertiary care hospital. Results: One hundred and seventy-three patients were included. Out of these, 82 (47%) patients were diagnosed to have malignancies, 58 (34%) patients had granulomatous inflammation either suggestive of or consistent with tuberculosis, 29 (17%) patients were diagnosed to have inconclusive biopsy results, and 4 (2%) patients had an inadequate sample for histopathological examination. There were no major procedure-related complications. Conclusion: USG-guided biopsy of the omentum is a safe and effective procedure. A thickened omentum can serve as an easily accessible site for biopsy, especially in patients who have ascites of unknown etiology and in those with a history of previous malignancy.

Pulmonary and cardiac involvement by cysticercosis is extremely rare, and is usually asymptomatic. We report the case of a 19-year-old boy who presented with a history of headache and vomiting and was found to have disseminated cysticercosis with pulmonary and cardiac involvement; the emphasis is on the rare occurrence of pulmonary, cardiac, pancreatic, intraocular, and extradural spinal canal involvement in the same patient. This case demonstrates the extent to which cysticercosis can be disseminated.